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Audio Precision^ System One is used
daily worldwide, by thousands of
design and test engineers and technicians at manufacturing firms, unskilled
operators at test stations, maintenance
engineers at broadcast stations and
recording studios, installation
engineers, equipment reviewers, consultants It rapidly and easily does performance testing of prototypes,
component evaluation, measures performance during environmental testing,
assists in alignment, does manufacturing testing from board to system level,
and verifies performance or helps with
trouble shooting in complex broadcasting, recording, and sound reinforcement systems System One is regularly
used in design, test, and maintenance
of power amplifiers, analog and digital
audio signal processors, distribution
amplifiers, routing switchers, mixing
consoles, equalizers, compressors, limiters, broadcast transmitters, loudspeakers, microphones, telephone
handsets and headsets, hearing aids,
crossover networks, tuners and receivers, CD players, RDAT recorders, professional digital audio recorders, analog
tape recorders, digital editors and disk
recorders, automotive stereo components, satellite communications circuits,
consumer stereo high-fidelity equipment, DSP equipment
Hour ifissif ffBtPwu?
System One is FAST— performs standard audio tests faster than other automated systems, twenty to one hundred
times faster than manually operated
instruments Stable, settled data is
guaranteed even at maximum speed
by System One's unique SETTLING
System One is EMYto use Select standard audio tests and complete procedures from directories via arrow keys
or by pointing at menu choices with a
"mouse" The panel and menu concept
eliminates any need for the user to
write or understand software
System One completes the measurement task with high resolution color or
monochrome GRAPHIC RESULTS viewable for interpretation while the test is
being made Print graphs to laser or
dot-matrix printers in 20 seconds' High
resolution multi-color plots can be
made to HPGL-compatible plotters
lower guaranteed residual noise and
distortion than any other automated or
semi-automated audio test equipment
Specifications are guaranteed across
the full range of real-world needs Balanced inputs plus balanced, transformer-isolated high level outputs and
multiple impedances for critical pro
audio applications Single-ended
outputs for consumer audio
products Digital audio inputs
and outputs in professional and
consumer formats to test in any
combination of analog and
digital domains
Flutter-tolerant distor-
•tonmeasurement ormtf% pius pfiase
; and wow and flutter measurement
capability for analog tape machine
measurements Thoroughly shielded
and filtered for operation in high rf fields
around broadcast transmitters
System One is FLEXIBLE1 test in accordance with industry standards or
create your own Define test conditions
such as levels, frequency limits for
sweeps, source and load impedances
System One compares results to standards which you define and provides
"go/no-go" response Link together a
series of sweeps and tests into a complete test procedure which runs automatically even by unskilled operators
System One is COST-EFFECTIVE, priced
low enough to replace manual test
equipment, productive enough to
quickly pay for itself in labor saved The
huge quantities in which PCs are manufactured make them far better buys
than dedicated computer/controllers
built for control of test instrument
System One is COMPACT No stack of
multiple boxes with complex interconnecting cables and differing display
and control schemes One instrument
rapidly makes virtually all standard
audio tests
System One measures frequency
response, weighted and unweighted
noise and signal-to-noise ratio, wideband or selective amplitude and noise,
real-time crosstalk, gain, loss, absolute
level, level with respect to any reference, real-time level ratio, total harmonic distortion plus noise, individual
harmonic distortion from 2nd through
9th harmonic, spectra via FFT to 3 Hz
resolution across the 20 kHz audio
band, three forms of intermodulation
distortion, mterchannel phase, inputoutput phase, linearity quantization
noise and distortion, wow and flutter by
both rotational and scrape techniques,
FFT spectrum analysis of wow and flutto 0 06 Hz resolution—plus generation of tone bursts, squarewaves, white
noise, pink noise, and 1/3 octave bandpassed noise Most of these measurements can also be made in the digital
domain on digital audio signals in the
AES-EBU or SPDlF-EIAJ formats, or any
other digital format which can be interfaced to a 24-bit serial or parallel connector A fuliy-software-integrated
companion instrument adds measurement of dc voltage, resistance, and the
value of a 21-bit digital word plus generation of two dc voltages and a 21-bit
parallel word Accessory switchers permit up to 192 channels of audio to be
tested Tests can be performed in
accordance with virtually all published
standards, including those of SMPTE,
System One Dual Domain adds digital
interfaces plus still more DSP capability
to generate and measure audio signals
in the digital domain in several formats,
including the professional AES-EBU format, the consumer SPDIF-EIAJ format,
and general purpose 24-bit serial and
parallel formats Combined with the
analog domain capability of all System
Ones, the Dual Domain series can thus
measure in any of the four possible
combinations of analog or digital stimulus with analog or digital acquisition
and measurement This series is called
the SYS-322 for full stimulus-response
capability and SYS-302 for a unit lacking
an analog generator
System One is a modular test system
with both analog and digital stimulus
and measurement modules which can
be fitted inside the basic enclosure.
Switcher modules in their own
enclosures may be added for testing
devices with more than two channels. A
multifunction unit in its own enclosure is
available for dc voltage and resistance
measurements, variable dc outputs,
and low-speed digital input and output.
The basic stimulus-response unit for
audio measurements in the analog
domain is the SYS-22, where the digits
indicate a two-channel (stereo) generator and two-channel analyzer Generator-only (SYS-20) and analyzer-only
(SYS-02) units are available, as is a single channel unit (SYS-11). A basic System
One without options measures THD + N
(total harmonic distortion plus noise),
phase, frequency wideband or selective (1/3 octave) amplitude and noise,
real-time crosstalk (selective), and realtime amplitude ratio.
Major additional capabilities for any of
these series include the IMD (intermodulation distortion) option, the W&F
(wow and flutter) option, and the BUR
(sinewave burst, squarewave,
pseudorandom and random white and
pink noise generator) option. All mount
internally within the System enclosure.
DSP (Digital Signal Processor) technology adds enhanced measurements
of analog domain signals. Standard
DSP programs are furnished which support individual harmonic measurements (2nd through 9th harmonics) and
other selective amplitude measurements, waveform display (digital storage oscilloscope mode) of signals to 80
kHz, and spectrum analysis via FFT
(Fast Fourier Transform) of signals to 80
kHz. DSP programs are downloaded
from the PC for flexibility and future
expansion. This unit, genericaily called
System One + DSI=5carries the nomenclature SYS-222 for a generator-analyzer package and SYS-202 for an
analyzer-only unit.
System One is available in three different computer interface versions. A suffix
character added to the model number
indicates the system computer interface. The character UA" indicates the
Audio Precision Interface Bus, operating
via a digital interface cable from an
Audio Precision-furnished PCI interface
card plugged into an expansion slot of
an IBM-PC compatible. US" indicates a
serial interface (RS-232) connection
from the serial port of an IBM-PC compatible running Audio Precision S1.EXE
software. UG" indicates a GPIB (IEEE-488)
interface, operating from any IEEE-488
controller-computer and requiring user
development of software. Both US" and
G" versions also include the Audio Precision Interface Bus, though only one
interface is usable at a time.
System One is unique in many respects.
No other audio test set incorporates so
many types of audio measurements
and signals. No other audio test set was
designed exclusively for operation from
a computer No other audio test set had
an extensive software package developed, in parallel with the hardware
effort, so that most audio tests are performed automatically by users with no
experience in programming or knowledge of computer languages.
Interconnection between computer
and instruments is normally via the
Audio Precision interface Bus, using an
interface card plugged into a computer
expansion slot. All control and display
functions are accomplished by the
Personal Computers deliver more function for their cost than almost any product available. System One exploits PC
capabilities for instrument setup data
storage, program storage, graphic and
alphanumeric display post-measurement processing, communications with
remotely located test systems, graphic
or tabular hard copy via an attached
dot matrix printer or laser printer and
high-resolution graphic output to HPGL
pen plotters and laser printers. The
basic strategy of Audio Precision's
design engineers was non duplication
in their instrument of all functions which
the PC couid logically perform. With PCcompatibles manufactured in millions
of units annually while audio test equipment manufacturers build hundreds of
units, the economies of scale make the
PC-based System One the most costeffective in the world. And, the manufacturing cost savings from not including dedicated displays and controls in
the instrument, more than pay for a personal computer!
Audio Precision^ comprehensive S1.EXE
software package is used by nearly all
A" version users and must be used to
operate any "S" version system. All of
the operating examples, menus,
graphs, and panels illustrated in this
brochure are part of the S1.EXE software
package furnished with every TV' and
S" version. For users with unusual
applications not supported by the features of S1.EXE, the LiB-MIX function
library is available for UA" version systems to provide instrument control from
user-written programs in Microsoft C,
Microsoft QuickC, Microsoft QuickBasic,
or Lattice C and running on an !BM-PCcompatible computer "G" version systems require user-created software,
written in the language and for the
operating system of the IEEE-488 controller which will be used, with Audio
Precision-documented commands
imbedded to control System One.
in earlier generations of test equipment
with hardware front panels, the measurement functions initially designed
are the only functions available for the
life of the instrument. Conventional
instruments are limited to the units of
measurement for which the designer
has panel room and meter scale
space, typically only Volts or dBm for
level and percent or dB for distortion.
Modes are limited by the number of
knobs and switches which can be usably located on a panel. System One,
with its "soft panel" on the computer
display can measure or be controlled in
any units. Most options can be added in
the field, with new panels selected by a
keystroke. Alphanumeric, analog bargraph, or color or monochrome X-Y
graph display modes are instantly
Analog domain:
Total system THD + N120-20 kHz, 80 kHz
measurement bandwidth <0.0015%: 22
kHz bandwidth <0.001%
Total system flatness ±0.05 dB, 20-20 kHz
Total system IMD <0.0018% SMPTE,
<0.002% DIM, <0.0005% CCIF
Analyzer residual noise <1.5 microvolts
(-114 dBu) in 22 kHz bandwidth
Digital domain:
THD+ N-12OdB (20 bits)
Flatness ±0.02dB
Analog and digital domains:
FFT spectrum analysis to 80 kHz with 8,192
line resolution. Waveform display to 80
kHz with pre-trigger, record length to 30.7k
System One automatically graphs
stereo response, distortion, and phase
sweeps from test CDs and standard reference tapes, even with voice
announcements between tones. Equalization mode controls generator amplitude during a frequency sweep to
follow standard curves such as RlAA
phono equalization or broadcasting deemphasis curves, user entered functions, or a measured and inverted
curve. Nested sweep mode automatically steps the generator amplitude
between frequency sweeps to produce
multi-trace graphs displaying response
across the full dynamic range of a
Mixing consoles, multi-track tape
machines, and racks of amplifiers are
automatically tested without cable juggling when the SWR-122 family of switchers is added. Variable dc outputs of the
DCX-127 permit graphing VCA (voltagecontrolled amplifier) performance while
gain and/or THD null voltage are automatically varied. Graphed spectrum
analysis of noise (by high-resolution FFT
or 1/3 octave spectrum analysis) quickly
locates hum, spurious signals, and
other noise sources. Definitive measurements of bit-weighting errors and quantization noise and distortion in digital
systems are made via amplitude-swept
THD measurements down to 25
A-D and D-A converters can be dynamically tested without additional, unnecessary conversions between analog
and digital domains. Sweep tests can
be made where the generator amplitude automatically adjusts at each frequency in order to hold an arbitrary
distortion percentage or power level
constant at the device output. Generator frequency can automatically
search for a measured output amplitude value such as -3.00 dB or the maximum response of a bandpass filter
Audio transmission links from studio to
transmitter or continent-to-continent
are tested in REMOTE mode. An operator at either end of the link controls
instruments at both ends, with data
graphing in real time at the control
point. REMOTE mode even permits testing at a remote, unstaffed transmitter
or repeater location. Computing utilities
show deviation from linearity equalize
results after measurement, center test
data between limits, smooth data
curves, subtract one test from another
at the touch of a few keys.
' DCX-127
Enhance your' engineering development, design, and research testing with
the power of System One,
Prove your finest designs with System
One^ ultra-high performance; typical
0.0007% distortion, 0.03 dB flatness, 1.2
microvolt noise levels in the audio
bandwidth. Use FFT analysis following
the analog notch filter to resolve distortion components 145 to 150 dB below
the fundamental.
Test virtually all audio parameters with a
single instrument. Measure THD + N,
individual harmonics through the 9th,
three forms of intermodulation distortion including transient/dynamic, phase,
frequency broadband and weighted
noise and signal-to-noise ratio to all
major international specifications, spectral distribution with 3 Hz resolution
across the audio band via FFT, selective
amplitude via swept 1/3 octave filter;
common mode rejection ratio,
crosstalk, wow and flutter (rotational
and scrape) with spectral analysis of
wow and flutter to 0.06 Hz resolution, dc
and resistance, and display waveforms
to 80 kHz bandwidth. Acquire digital
audio signals and analyze them in the
digital domain. Generate ultra-low distortion sine waves (+ 30 to -90 dBm, 10
Hz to 204 kHz), three intermodulation
test waveforms, two variable dc outputs
with 20 microvolt resolution, square
waves, pink noise, white noise, 1/3
octave filtered noise, and continuous,
triggered, or gated sine bursts with
complete control over burst duration,
burst interval, upper and lower amplitudes. Generate 24-bit accurate signals
in the digital domain.
Graph results in real time for easy interpretation of measurements. Or; display
data in tabular format for highest precision. Select display units including Volts,
dBm, dBu, dBy dB relative to any refer-
ence, %, amplitude ratio, frequency
ratio. Re-scale and zoom graphs and
change units after data is taken. Save
any test data to disk. Print lab notebook
graphs to inexpensive dot matrix
printers or laser printers. Print publication quality graphics to plotters (in multiple colors) and laser printers. Overlay
multiple graphs for comparison.
Choose frequency or amplitude of analog or digital sinewaves, time, switcher
channel, or variable dc output voltage
as the swept independent variable of a
test and horizontal axis of a graph.
Select one or two parameters to be
measured and plotted in real time versus the independent variable. Save any
test setup to disk under a name you
create. View four measured parameters simultaneously in numeric display
format, or three as analog bar graphs.
Plot one measured variable against
another "Nest" amplitude and frequency sweeps to provide full spectral
and dynamic range information in one
test, on one graph. Simplify adjustments with bar graphs; use mouse or
arrow keys for smooth, continuous control of generator increment amplitude
or frequency in any arbitrary step size.
Sweep frequency while generator
amplitude follows any desired function
via EQUALIZATION mode. Select equalization curves from standard furnished
functions (RlAA, pre and de-emphasis
curves), or create your own. Calibrate
out cable and system non-flatness by
inverting a measured response and
using it as an equalization curve.
Sweep frequency while the generator
amplitude automatically adjusts to
maintain constant some measured
parameter such as distortion or power;
via REGULATION mode.
Save test data in a format compatible
with statistical analysis packages, all
popular computer languages, and personal computer programs such as
spreadsheets and data base management. Display group delay following a
phase vs frequency sweep. Smooth,
normalize, invert, display deviation
from perfect linearity subtract curves
with standard internal computational
Verify production quality rapidly thoroughlyrepeatablyat the module,
board, complete equipment, or system
levei with System One. Speed performance tests up to 100 times over manuai
methods; use the time saved to reduce
test costs or Increase testing confidence. Perform tests at exact frequencies and amplitudes specified in earlier
manual test specifications. Make virtually all audio tests including harmonic
and intermodulation distortion, wideband and selective amplitude and
noise measurements, crosstalk, phase,
frequency wow and flutter; dc voltage
and resistance, digital input/output with
one compact high performance unit.
Test multi-channel devices or multiple
nits via SWR-122 audio signal switchers.
Conserve scarce technician skills by
using less-experienced operators for
production testing since test setups,
measurements, and decisions are
computer-controlled. Create procedures which specify test sequence
and instrument setup, control other
Prepare procedures in minuti&s-tohours without knowledge of programming languages, rather than the
weeks-to-months of experienced programmer time required to write software for other test systems. Specify
limits for each test. Limits can be
devices, display bargraphs for required
adjustments and prompt the operator
Replace the computer keyboard with
a simple, limited-function keypad or
buttons. Use
no-display mode
to avoid confusing
operators with
information they
need not interpret,
while the system makes go/no-go decisions. Drive pass/fail indicators or
device handlers to separate good and
bad units.
entered from engineering data or generated by averaging test data from
acceptable units. Create on-screen
menus for operator selection of test
type. Halt or branch to other procedures
upon out-of-limits measurements. Print
automatically-generated error summary files as failure tags and quality
records. Test every unit at rated output,
even if gain varies from unit to unit, with
REGULATION mode. Slide data vertically
for best fit between limits via COMPUTE
CENTER when response curve shape is
important but sensitivity is not.
Print graphic or tabular data for shipment to customer or company files.
Duplicate earlier tabular reports by
exporting data to spreadsheet software. Dump data to disk for later statistical analysis. Network to a central
computer for data storage.
Control the UG" version System One from
any IEEE-488 controller or combine an
A" version system and IEEE-488 instruments by using IEEE-488 and Audio Precision interface cards in the same PC.
Write custom software in QuickBASIC, C,
or QuickC using the LIB-MIX function
Rapidly align and verify performance of
stereo and multi-track reel to reel and
broadcast cartridge decks and audio
channels of VTR and VCR machines.
Test for distortion (THD + N with all systems, or 2nd or 3rd harmonic with DSP
units) at any audio frequency in recordplayback mode on three-head
machines or in reproduce mode from
or serial interfaces for unattended testing. Perform completely automated
alignment of the studer A820-A812-A810A807 series, both reproduce and record
Measure print-through and depth of
erasure. Test tape media by controlling
bias current of a modified tape
machine. Graph tape sensitivity versus
bias. Use REGULATION mode to measure MOL and SOL (saturated output
level) vs bias.
Perform wide-range input vs output
amplitude sweeps and display deviation from perfect linearity
Align reproduce and record sections.
Adjust azimuth with bargraph displays
of 2-channel amplitude plus phase or
repeating phase-vs-frequency sweeps
for completely non-ambiguous adjustments. Automatically graph stereo
reproduce frequency response from
existing reference tapes, even those
with voice announcements between
sweep mode. Measure frequency
response of three-head machines with
any amount of delay between heads
via System Ones asynchronous architecture and SETTLING DELAY parameter
Optimize bias using overbias or minimum distortion techniques. Simplify
overbias adjustments with the bargraph MAXIMUM HOLD feature which
displays both peak and present values.
Repeat a fast frequency response
graph automatically while adjusting
record equalization on three-head
Find crosstalk below noise level via
BANDPASS or CROSSTALK modes. Quickly
optimize crosstalk adjustments on
stereo machines with simultaneous
screen display of L-R and R-L crosstalk.
Measure wow and flutter by IEC/DIN,
NAB, JSS methods in the rotational
spectrum {<200 Hz) and via wideband/scrape methods (5 kHz bandwidth). Use COMPUTE 2-SIGMA to
produce a single number wow and flutter result. Display drift (speed error). Perform FFT spectrum analysis of wow and
flutter to 0.06 Hz resolution to quickly
identify diameter of the defective rotating part.
Plot MOL (maximum output level) via 3rd
harmonic distortion. Discover bias
waveform and magnetization problems
via 2nd harmonic distortion.
existing reference tapes or those you
record. Distortion measurements are
flutter-tolerant due to System One's
patented two-stage notch filter
Connect the SWR-122 switchers to 24or-32-track machines. Touch one key or
use a mouse to move from track-totrack while aligning via bargraph display. Make response tests of ail tracks
in S minutes. Create a procedure which
runs complete 24/32 track performance
verifications in 20-30 minutes, without
operator assistance. Measure worstcase crosstalk by driving all but one
channel while measuring that channel.
Graph gap scatter across 24-and 32track heads in 10 seconds.
Control the tape transportV\a parallel
human hearing. Measure polarity and
rub and buzz. Measure and compute
Thieie-Smali parameters at the voice
coil in five seconds.
Measure microphone and telephone
handset response by comparison to a
reference microphone or using a standard artificial voice. Test microphones
by four methods:
Test frequency response of loudspeakers, headphones, hearing aids,
headset earp^ces using a standard
Terence microphone and swept sine
^/aves, pink noise, white noise, or 1/3
octave bandpassed noise. Select wideband analysis, swept ANS11/3 octave
Class Il selectivity or FFT spectrum analysis. Process data with the COMPUTE
SMOOTH feature to correlate better with
Adjust and verify performance of analog and digital tape machines, consoles, distribution amplifiers,
processors, microphones, power amplifiers, and other studio equipment with
System One. Standardize test methods
via stored setups. Document automatically with disk-stored or paper-printed
graphic or tabular results. Compare
results graphically with past measurements to predict replacement needs.
Run a procedure which makes multiple
tests quickly and consistently independent of the operators skills. Automatically test complete mixing consoles,
Graph acoustical test results at any
desired vertical and horizontal resolution. Calibrate dBr (dB relative) as dB spl.
Create test limits from measurements
of a "golden unit", or from the average
of measurements of many units.
• at constant sound pressure level via
REGULATION mode which adjusts generator amplitude at each frequency
to hold reference microphone output
(spl) constant
• by graphing the difference between
microphone under test and reference
mic, in real time
• using an equalized generator sweep
which adjusts speaker input power to
compensate for measured response
of speaker and room
• using COMPUTE DELTA to subtract previously measured speaker/room
response from the measurement
routing switchers, and muiti-track tape
machines with the SWR-122 audio signal
switchers. Make worst-case crosstalk
measurements by driving all but one
Slide microphone measurement curves
vertically for best fit between response
limits, using COMPUTE CENTER.
Measure power-based (impedance
matched) and voltage-based systems,
using transducer gain or voltage gain
methods. Make dBm (power) measurements with reference to any impedance. Terminate fully balanced analyzer
inputs in 150 or 600 Ohms (300/600 Ohm
option available) or select bridging
mode. Drive at + 30 dBm levels for
headroom tests. Drive at microphone
equivalent levels without external
attenuators. Select 50/150/600 Ohm output impedance fully transformer balanced. Measure common mode
rejection ratio without disconnecting
cables or searching for matched equivalent source resistors. Measure noise
without disconnecting cables or connecting terminations, since the generator back terminates when off
Overlay graphs of multiple settings of
EQ circuits. Track down noise sources
via swept or FFT spectrum analysis.
Drive dynamic processors with a tone
burst signal giving full control of frequency, duration, interval, and amplitude between bursts. Evaluate transient
response with a square wave and
waveform display mode of DSP-based
System Ones.
Use pink noise or 1/3 octave bandpass
noise for acoustical measurements.
Graph microphone response relative to
a reference mic, independent of loudspeaker and room response.
Ouickiy test A-D and D-A converters, professional digital tape recorders, digital
mixing consoles, digital processors, digital audio tracks of VTRs,, CD players. RDAT
machines, digital workstations and
direct-to-disk systems, digital transmission links, DSP prototypes.
**XJ £3t-3*Z
Directly connect to digital audio device
inputs and outputs via the two-channel
professional (AESIEBU) interface, consumer (SPDIF-EIAJ) interface, generalpurpose 24-bit parallel interface, or
general-purpose 24-bit serial interface.
Generate sinewaves of any amplitude
and frequency with the analog generator or up to 1/2 the sample rate with 24bit frequency and amplitude resolution
in the digital domain. Set digital generator levels in dBFS (dB below digital full
scale) and %FS. Lock the sample rate of
generated signals to "house sync" by
use of the external sync input. Acquire
signals in analog or digital domains. Display waveforms of signals acquired in
the digital domain, from full scale to the
minimum theoretical amplitude digital
devices in all four possible combinations: A-D, D-A, D-D, and A-A.
lute units to show bit-weighting errors in
Make definitive measurements on the
best D-A systems via digital generator
distortion of -130 dB, analog domain
residual THD + N below -100 dB (typically -106 dB at the standard output
level of CD players), amplitude resolution
of 0.01 dB, typical flatness of 0.02 dB. (¾
resolve distortion products more
than 145 dB down by analog notching
out the sinewave fundamental followed
by FFT analysis. Select triangular or rectangular probability distribution dither at
any LSB level, or undithered.
signal. In the digital domain, measure
THD + N (20-bit residual distortion),
response, weighted or unweighted
noise, linearity Use the same measurement concepts in analog and digital
domains to make the results directly
comparable. Make digital domain
amplitude measurements in dBFS and
%FS, plus THD + N measurements in dB
and BITS. Graph frequency response or
THD + N of digital recorders and similar
Measure linearity across a 110 dB
range in dithered systems via widerange amplitude sweep and frequencyselective amplitude measurement in
digital or analog domains. Use COMPUTE LINEARITY to display deviation from
perfect linearity. Measure THD + N at 25
microvolt levels as part of quantization
distortion sweeps across a 110 dB
dynamic range. Graph THD + N in abso-
Measure the best A-D systems via analog generator THD + N below -106 dB
(harmonics typically below -120 dB at
fundamentals from 20 Hz-5 kHz), digital
domain residual THD+N below -120
dB, amplitude resolution of 0.01 dB, flatness of 0.02 dB.
Identify clock leakage and aliased or
other out-of-band analog signals
through swept 1/3 octave spectrum
analysis up to 200 kHz or high-resolution
FFT spectrum analysis to 80 kHz.
Measure input/output phase shift and
display group delay of anti-aliasing
and reconstruction filters.
Compare spectra of two digital or analog channels via twochannel FFT spectrum analysis; use two-channel graphic
cursors for precise readout of amplitude at any frequency Make "before
and after" comparisons by acquiring
the two channels at different times.
Dithered vs non-dithered signals from
ie same CD player are shown in the
Capture signals in the analog or digital
domains, save to computer disk for
later analysis, display as waveforms or
FFT spectra.
Test CD players and playback-only systems in EXTERNAL sweep modes, using
existing test discs or tapes. Make comprehensive CD player measurements.
Ask for the Applications Note and diskette of tests and procedures for CD
player testing.
Adjust MSB trim ofD-A and A-D converters for best linearity using a repeating low-level amplitude sweep from
digital or analog generator; narrowband
analog or digital amplitude measurement, and the "sweep-erase-repeat" X-Y
graphic display mode.
the sinewave signal. Measure transfer
function of D-A converters with the constant ("digital dc") signal and dc voltage
measurement via the DCX-127. Measure
monotonicity and low-amplitude linearity of D-A converters with the staircase signal and waveform display.
Measure time delay through a digital
device with the impulse signal.
Measure hit errors of digital interfaces,
digital transmission paths, and digital
storage media with any amount of
delay between input and output. Generate pseudorandom, walking 1 and
walking O1 staircase, ramp, impulse,
constant and sinewave signals,
Locate "stuck bits" with the walking bit
signals. Measure bit errors through digital devices with gain or loss by use of
Make audio proof-of-performance
tests in minutes on FM, AM, and TV
stereo and monaural stations. Generator output will automatically adjust
for constant modulation at each frejency with REGULATION mode. Use limits files to compare
measurements to
requirements, and
instantly center
between the limits. Control generator amplitude with 75
usee or 50 usee de-emphasis curves.
Applications packages available for U.S.
FM and TV stereo testing.
Perform fast system tests when transmitter-demodulator are remote from
studio via "splitsite" architecture. Control generator at studio and analyzer at
transmitter from either location, graph
real-time test results at either location. Test remotely located equipment at distant, unmanned transmitter
or repeater locations. Perform automatic, unattended performance tests
of broadcast stations and networks.
Test broadcast networks or simple
links without modems via EXTERNAL
FREQUENCY mode at the destinations
and a sweep from the origination.
Graph response, distortion vs frequency
from present repeating step-tone
Measure transmission circuit phase vs
frequency and display group delay.
Sweep stereo systems and graph
both channels, or level difference
and phase between them, in one
rapid sweep.
Operate in high rf environments due
to System One's shielding and filtering
—tested at Mt. Wilson, South Mountain
Phoenix, and adjacent to half-megawatt
Analog generator sweeps are completely software controlled, so amplitude can follow any arbitrary function
as frequency sweeps. Applications
include broadcasting de-emphasis anc
pre-emphasis curves, RlAA curves,
equalization according to an equation,
or data you enter \bu can even make a
response measurement of long cables,
invert the curve and use it as an EQ
curve, and produce flat response at
the cable ends as the generator
makes equal but opposite amplitude
changes to compensate.
System One software and hardware
provide two means of frequency control. FAST mode settles in a few cycles
and provides frequency accuracy of
0.5%, adequate for most audio measurements. HIGH ACCURACY mode provides 0,005% resolution and 0.03%
accuracy but takes approximately 150
milliseconds every time frequency is
\ entry-fields, such asgenemmr'AMPU; TUDE or FREQUENCY* let you type any
System One'sfi4JW££mode is the real
fmm panel"0 of the instrument* Um It ; number wfth common engineering
to set up newtesteand modify old
\ pmfim$ such as k for kilo-, m for
ones, Use it for impmmpm, 1^pOf*
miiih u for micro—or me integer or
measurements whh up m nine values
I scientific notation* Multiple choice
displayed simultaneously—IEVEL,
\ fields, such as selection of measumFREQUENCY, PHASE, your choice of I ment units or choice of principal wolt«
principal BBADiNC memr functions
\ memr function, show the awaiiabie
impumm* BANDPASS, BANDREJECT,\ choices attfie bottom of'the panel*
I Make your choice with the mouse or
TER, 2-CHANNEL, CROSSTAm, Cfc VC*-i <Enmr> key
age or resistance, digital word walue*
\ Any three functional panels (gener> and up to 3 DSP-measured paramamr, analyzer, simep panels shown
eters. Readings update in mai time
below) wisible at the same time—
: as you modify settings.
reduces mscmen hopping**, Genemmr
, amplitude or frequency may be
i Mowe #>© cursor m a field with arrow
I Incremented in any desired step size
Joeys or mouse. Fields are numeric
\ wia AMPSTEP and FREQSTEP fields*
m entry or multiple choice. Numeric
System One software features the
industry^ widest selection of units. Volts
RMS and dBm units are common on
other equipment; System One also provides choices including Volts P-f?dBu
(relative to 0.7746 Volts), dBV (relative to
1.000 Volt), dBr (relative dB), dBFS (relative to digital full scale), BITS (for distortion levels in digital systems) and Watts.
System One's dBm units are true dBm,
taking into account circuit impedances
for actual power indications; nearly all
other instruments actually measure
dBu when their \IBrrf mode is
selected. Furthermore, dBm and watts
units may be used with any value of
external resistance by entering the
resistance value, letting the computer
do the calculations. A most useful unit is
dBr—dB relative to a reference amolh
Acceptance LIMITS are easily generate
: and attached so that pass/fail results
can be obtained. The limits can be
: easily created from a specification or
\ can result from a test or the average c
I many tests. An error-reporting file can
\ be specified, into which System One
writes a summary with test name, dat
; time, and out-of-spec readings or the
I statement 7\ll data within limits". The
I same file may be named for every tes
I in a procedure, resulting in a master
\ test summary file for the entire
tude which you enter from the keyboa?
or store from the present measuremei
by pressing a key dBr instantly sets the
reference for signal-to-noise, gain-loss
and frequency response
moAQ! irpmontQ
Most audio testing consists of a few or
few dozen tests such as response, dis
tortion versus frequency crosstalk, or
noise level. Examples of those and
other common tests are furnished on
diskette with System One. To run a test
press L T (LOAD TEST) and a directory o
stored test files will be displayed. Sefec
a test with the cursor press F9 to run,
and (if you wish) save the results. Modil
furnished tests to your exact requirements and save them under another
The two bottom lines describe how tn
make changes—when to enter digit
when to select with the space bar; ar
hnw in pnter th£» rh^nap
Most audio tests are sets of measurements, best analyzed from a graphic
presentation. System One provides the
SWEEP DERNtTlONS panel for easy
I setup of sweep tests. Choose frequency or amplitude sweeps, scans
across switcher channels, dc or digital
output, or measurements versus time
(oscilloscope/chart recorder mode) for
I the horizontal graph axis. Specify any
! START and STOP values for the sweeps #
STEPS, and LOG or LIN. Intermediate
points will be automatically computed,
or the sweep may be from a TABLE with |
any arbitrary values you choose. Select !
one or two measured parameters, such !
as LEVEL and PHASE, THD + N and LEVEL,
or LEVEL on both stereo channels to be
lines on the graph. Specify LOG or LIN
vertical scales with any value for GRAPH
TOP and BOTTOM calibrations. Press the
F9 function key for a fast on-screen test
with mal-time graphing of results. If
thereS anything you don't like about the
presentation, zoom or change coordlnates or units and re-graph without retesting, via the F7 function key
Some audio devices have no real-time
input; examples Include compact disc
players, playback-only tape machines,
satellite downlinks carrying a distantagination signal. System One automatic graphs data from such devices
when the signal is a swept or stepped
mode, System One measures the
I Incoming frequency plus two other
I selectable parameters such as distortion, phase, or stereo amplitude. Each
time the frequency changes, System
i One makes and graphs another meaI surement Vbice announcements
recorded on reference tapes are
ignored; only the tones are plotted.
Measurements are graphed as they are
made, in either MONO GRAPH or COLORGRAPH mode. System One software
supports the full resolution of VGA, EGA,
CGA, and Hercules high resolution
monochrome graphics systems. When
two parameters are measured, both
graph as y-axis values versus the swept
parameter on the x-axis. Solid and
I dashed lines (green and yellow on a
color monitor) plot the two parameters,
In VGA and EGA systems, up to four
sweep repetitions are displayed in different colors, Two measured values
I may be graphed versus one another,
I such as distortion (on the y-axis) versus
output power of an amplifier (on the xaxisl Data can also display in tabular
! form, with out-of-limits readings flagged
I as the test progresses.
When several tests have been created
and saved, they may be easily linked
into a test PROCEDURE which loads and
..runs as a single unit. Procedures may
nsist of tests, control signals to external devices, prompting messages to
the operator, pauses until a condition is
sensed at an externa! device, pauses
for operator input, sub-procedures, and
temporary exits to the computer operating system (DOS) to run programs outside System One. IEEE-488 instruments
may be controlled in a procedure via an
IEEE-488 interface card and temporary
exits to IEEE-488 control software.
Procedures are easily created in "learn"
mode which memorizes keystrokes as
you go through the sequence. You can
edit procedures in a full-screen editor
OC t h r u «
System One uses a simple menu system. Select menu actions by using the
space bar to move a cursor to your
choice, then press <Enter>. Even
faster, type the first letter of the desired
menu commands. Examples include S
T (SAVE TEST) to save a setup and data
to disk, L T (LOAD TEST) to bring a stored
setup and data from disk, R P (RUN PROCEDURE) to start execution of an entire
series of tests, U L (UTIL LEARN) to start
the keystroke-learning process which
generates a procedure. With only two
levels of menu, you won't bog down in
menu drudgery". The complete menu
"tree" is reproduced at the right.
Uun procedure, test, graphs.
Run a procedure.
Measure and graph new data
Graph stored data.
Display readings on Bar-graph,
Cause instruments to be LOCAL
Enable REMOTE instruments.
Split-site Slave mode.
Call a sub-procedura
Exit from a sub-procedure.
Display Instrument panels.
Load test, data f r o m disk.
Load test from JST file.
Load test from HM file.
Load test from .SWP file.
Load comments from disk.
Load procedure from disk.
Load macro from disk.
Load ASCII data from .DAT file.
Load test from £Q We.
Load test except punch-outs.
Load waveform from disk.
Save test, data t o disk.
Save test to JST file.
Save test to .LlM file.
Save test to .SWPfJIa
Save comments to .TXT We.
Save procedure to .PRO file.
Save macro to .MAC file.
Save ASCII data to .DAT file.
Save test to .EQ file.
Save test except punch-outs.
Save graphics display list.
Save waveform to .WAV file.
Append f r o m disk.
Append data from .TST file.
Append data from ,DAT file.
Edit text or data.
Edit comment buffer
Edit procedure buffer
Edit data buffer
Edit macro buffer
Show tielp menu choices.
Show function keys screen.
Show Overlay screen.
Show Text Editor screen.
Show DSP screen.
Show mnemonics screen.
Execute OHE DOS command.
Select compare limits, etc.
Select upper compare limit
Select lower compare limit
Select sweep source table.
Select We for generator eq.
Select file for error reporting.
Disable error reporting.
Select title for graphs.
Select new test name.
Clear Named files,
Select file for COMPUTE DELTA.
Select Program file for DSP
Conditional execution.
Do only if test error
Do only if not test error
Do if above limit
Do if below limit
Do if QRL-FlO response.
General utilities.
Reset hardware.
write to output port
Wait for value at input port
Delay for specified time.
Put a break in procedure.
Begin learning procedure.
End learning procedure.
Make prompt in procedure
Make message In to error file.
Go to label in procedure.
Digital I/O configuration,
Enter Channel Status Data.
Refresh received status data.
Serial digital intfc modes.
AES-EBU DSP digital mode
SPDiF DSP digital mode
SERIAL DSP digital mode.
Triangular DSP dither
Send form feed to printer
Quit program t o DOS.
Select data computation.
Normalize data values specified,
invert (reciprocate) DATA-],
Smooth data.
Deviation from Best Fit Line,
Center data between limits,
Subtract DELTA file from data.
Max excluding peak 5%
Exchange DATA-i and 2.
Enter label for UTiL GOTO.
System One can save data as an ASCII
file with values separated by commas,
this format is compatible with most
software languages and other programs such as Lotus 1-2-3, dBASE IN,
and statistical programs which do computations such as averaging and standard deviation Graphs can be
captured on-screen, then edited with
"Paint" software and sized or cropped
with desktop publishing software for
inclusion in data sheets or manuals
When graphing phase, System One
software doesn't display discontinuities
when the phase change exceeds 360
degrees. System One automatically
adds integral multiples of 360 degrees
as necessary to display a continuous
plot of phase—even through thousands of degrees of rotation.
Adjustments such as nulling or peaking
are easiest with an analog display System One furnishes several such displays via BARGRAPH (F2 function key)
mode. You have total control over bargraph units and calibration. One, two, or
three measured values may be simultaneously displayed on bargraphs.
Generator frequency or amplitude or
switcher channel may be controlled on
stimulus bargraphs by mouse or arrow
keys while up to two measured values
are displayed.
Any number of sweeps
may be overlaid, such
as when changing
settings of equalization
controls on a device
under test. A sweep
or a disk-stored test
can be re-graphed,
followed by a new test
on the same graph. A composite image
can be built up from any number of
graphs. A sweep-erase-repeat mode
simplifies adjustment of device controls. Nested sweep capability gener-
ates a family of sweeps, such as
frequency sweeps with each at a higher
amplitude or on a different channel.
Multiple sweeps are displayed in different colors on VGA and EGA displays.
With fast reading rates (32/second
under most conditions), automatically
switched detector time constants, careful selection of low-frequency rolloffs,
and automatically switched high-pass
filter; System One was designed for
SPEED. 30-point frequency response
tests of both stereo channels made
and graphed in 10 seconds. 16-point
distortion sweeps made and graphed
in 10 seconds. Response tests of 24
tracks of a tape recorder made and
graphed in 4 minutes. Thiele-Small
parameters of a loudspeaker in 10 seconds. Most important—these speeds
are achieved with fully-settled data,
not merely listings of how many "garbage points" can be taken "on the fly".
Many automated systems have reading
rates faster than the settling time of
either the device under test or the analog portions of the instruments. Many
other systems cope with this problem
by inserting a fixed time delay after
each generator amplitude or frequency
change. If the delay is long enough to
handle worst-case settling times, operation is greatly slowed under normal
conditions. System One software solves
System One provides easy plain paper
copies of graphs. The graph on screen
is reproduced in 20 to 40 seconds on
an inexpensive Epson-compatible dot
matrix printer or HP LaserJet printer If
you use EDIT COMMENTS capability to
type additional information, it saves to
disk with the test and prints below the
graph. High-resolution graphs can be
printed by an HPGL plotter or laser
the settling problem by continually
comparing a series of measurements,
using an "acceptance window" or
"envelope" whose shape and tolerance
you vary to fit each application's need
for settled data. The result is settling
speed adaptively optimized under a
wide variety of signal conditions, meeting your requirement for accuracy
which only you can specify.
' Sykem one specifications are guaranteed specifications across a full-range
of real-world conditions When "typcaP
performance is also shown, it is clearly
identified as typical and represents performance of the large majority of units
shipped, operating under normal
environmental conditions Audio Precision does not subscribe to a philosophy
of quoting performance with qualifiers
like uas low as" or over a narrow amplitude range centered at the "sweet voltage" where the instrument functions
best Graphs of performance over wide
frequency and amplitude ranges are
furnished in many cases
System One combinations are made
up of selections of the modules and
options described in the following
pages DSP modules mount in the
lower left compartment The IMD (intermodulation distortion) option adds
plug-on IMD modules to the generator
and filter module of the analyzer The
BUR (tone burst noise-squarewave)
option adds a plug-on generator module The W&F (wow and flutter) option
adds a plug-on module to the principal
voltmeter portion of the analyzer
The SWR-122 family of switchers and the
DCX-127 multifunction unit are separately packaged modules which may
stack or rack mount Their control
cables are "daisy chained" on the digital interface cable to System One
All specifications subject to change without notice.
Product and Shipping Weights:
System One and the DCX-127 operate
from line voltages of 100,120,220, or
240 Volts rms + 5/ -10%, 48-63 Hz System One draws 200 VA maximum, the
DCX-127 draws 20 VA maximum The
SWR-122 switchers operate from 90-126
or 180-250 Volts rms, 48-63 Hz, and
draw 20 VA maximum All meet performance specifications at temperatures from 5 to 40 degrees Celsius
SYS-nn (full options)
Net Weight
33 lbs (15 kg)
Shipping Weight
44 lbs (20 kg)
10 lbs (4.5 kg)
10 IbS (4.5 kg)
125 lbs(5J kg)
12.5 IbS (5.7 kg)
(h x w x d)
S75X17.25X17* (133x43.8x43.2 cm)
(4.4x435x27.9 cm)
1.75x17.1x10.75" (4.4x43.5x27.3 cm)
The Audio Precision System One generator features a true
transformer-coupled balanced output, ultra-low distortion,
and wide dynamic range Patented circuit techniques combined with a custom transformer design virtually eliminate the
problems associated with electronically-floating output
designs, with no compromises in performance Standard connectors include both male XLR (pin 2 high) and dual banana
jacks, wired in parallel (Specify option "GXPH" to substitute
a 1/4-inch stereo phone jack for the XLR) Separate ground and
output common banana jacks are also provided
Measured with a passive notch filter and spectrum analyzer
Valid for any R,oad ^300O
20 HZ3-20 kHz
10 Hz-100 kHz
0 0005% (-106 dB)
0 0050% (- 86 dB)
The generator has two frequency setting modes HIGH
ACCURACY mode initiates an auto-calibration cycle following
each frequency change This cycle takes approximately
150 msec above 50 Hz7 increasing to about 0 75 sec at 10 Hz
Until the cycle is completed, accuracy and resolution are the
same as the FAST mode FAST mode is recommended for
most applications where speed is important and 0 5% worst
case accuracy is sufficient Stability is typically < 0 01%/°OC in
ther mode
Balanced, Unbalanced, or Com
mon Mode Test (same as balanced
except generator is connected
between the output common and
source impedance center tap)
Source Impedance
50-150-6004 O balanced, or
25-6004 ft unbalanced, ± 1 H
Source impedance does not
change with output OFF
Generator amplitude can be set and displayed in a wide variety of units including dBuA/olts-mV-uV open circuit, dBm/WattsmW-uW into any specified load resistance, or dB with respect
to any reference The output amplitude at the front panel terminals can also be monitored by the System One analyzer via
its GENERATOR MONITOR input selection Residual generator
leakage in output OFF state is virtually non-existent, typically
<80 nv (140 dBu)
Maximum Rated
Floating Voltage
42 V peak ac, 60 V dc True
transformer isolation
Engineering benchtop applications often require an interactive
control of the generator parameters System One allows both
generator frequency and amplitude to be incremented or
decremented using keyboard keys or an optional mouse Virtually any frequency and amplitude step sizes may be
selected Steps can be additive or multiplicative (for example,
+ 0 25 dB steps or xl 256 frequency steps)
10 Hz-204.775 kHz
High-Ace Mode
Fast Mode
0.025 Hz, 10 Hz to 204 Hz
0.25 Hz, 205 HZ to 2.04 kHz
2.5 HZ, 2.05 kHz to 20.4 kHz
25 HZ, 20.5 kHz to 204 kHz
20 Hz-50 kHz
10 Hz-204 kHz
Sync Output
LSTTL-compatibie squarewave signal for triggering stable oscilloscope displays with all signals.
Monitor Output
Ground-referenced replica of the
generator signal. Nominally 2.8 V pp
amplitude, Rout = 560 O.
Trigger/Gate Input
LSTTL-compatible input for use with
the tone burst option.
SYS-22 and SYS-20 configurations provide a second switchable
generator output. Frequency amplitude, impedance, and
mode selection apply to both outputs simultaneously Both
outputs must be properly terminated in the A & B and A & - B
modes for correct amplitude calibration using dBm or Watts
Output Modes
A only B only A & B, A & - B, or OFF
Output Separation
<25 sxVrms-26.66 Vrms
« - 9 0 dBu to +30.7 dBu)
<25 jxVrms-13.33 Vrms
« - 9 0 dBu to +24.7 dBu)
Maximum Output Power
(both channels loaded)
into 600 ohms
into 150 ohms
Maximum Output Power2
into 600 ohms
+ 30.0 dBm, R5 = 50;
+ 24.7dBm,R5 = 600
into 150 ohms
+ 30.0 dBm, R5 = 50
<0.01 dB or 1.27 ^y
±0.1 dB (1%) at 1 kHz
Flatness (1 kHz ref)
± 0.03 dB, 20 Hz-20 kHz;
+ 29.4 dBm each load, R5 = 50;
+ 24.3 dBm each load, R5 = 600
+ 24.0 dBm each load, R5 = 50
Unloaded (open circuit). Divide maximum amplitude by 2
(-6 dB) for unbalanced or common-mode configurations.
Total peak output current rating is 120 mA balanced/ 240 mA
unbalanced, 20 Hz-20 kHz.
whichever is greater
110 dB to 20 kHz
25 Hz if output open circuit voltage exceeds 20 Vrms balanced, or 10 Vrms unbalanced.
5pecify option "EURZ" to substitute <40-200-600 (1 balanced,
<20-600 ohm unbalanced impedance selections.
The System One analyzer contains two independent voltmeters The "READING" meter displays the selected measurement mode and has the greatest senstivity and dynamic
range The TEVEL" meter monitors the wideband input signal
following input attenuation and pre-amplification, before subsequent signal processing, filtering, and additional gain stages
Its most sensitive range is 80 my limiting full performance to
inputs 2*10 mv (-38 dBu) In the 2-CHANNEL and CROSSTALK
modes the LEVEL meter displays the amplitude of the alternate input (SYS-22 and SYS-02 only), thus enabling simultaneous amplitude measurements on both input channels
Inputs are fully differential (balanced) with female XLR (pin 2
high) and dual banana jack connectors (Specify option 11LXPH"
to substitute a 1/4-inch stereo phone jack for the XLR) An additional unbalanced and switchable Auxiliary Input (Channel-A
only) is provided for special applications
Amplitude can be displayed in Vrms, dBV (1 000 Vrms ref), dBu
(0 7746 Vrms ref), dBr with respect to any predefined or measured reference, or dBm/Watts computed into any arbitrary
resistance The READING meter has selectable rms, average,
peak, Q-peak (per CCIR Rec 468-3), and S-peak detectors, the
LEVEL meter detector is rms only Measurement resolution is
approximately 0 004% (1/25200) of range at M/sec", varying to
0 032% (1/3150) at u32/sec" All displays are rounded to 4 digits
! The Bandpass/Bandreject modes provide selective amplitude
measurements processed through a 4-pole constant-Q filter
Filter tuning may be directly programmed ("FIXED"), tracking
("AUTO"), or swept for spectral displays Units selection and resolution are the same as the Amplitude measurement mode,
but with one additional range of sensitivity
Amplitude Ranges
75 ixV-160 Vrms (6 dB steps above
80 my 12 dB steps below 80 mV)
Tuning Range (f0)
10 Hz-200 kHz, ± 3% accuracy
Bandpass Response
± 0 5 dB (at f0), 20 Hz-120 kHz,
1/3-octave Class Il response
per ANSI 51 11-1975
Typically <-32 dB at 0 5f0 & 2 0fo
Bandreject Response
± 0 3 dB, 20 Hz-120 kHz, excluding
the band from o 5f0 to 2 0fo
Typically -3 dB at 0 73f0 & 1 37f0,
-20 dB within ± 10% of f0, and
-4OdB within ±3%off 0
Bandpass Noise
(input shorted)
0 5 JXV (-124 dBu), 20 Hz-5 kHz,
1 0 JJLV (-118 dBu) to 20 kHz,
2 5 JJLV (-11 OdBU) to 120 kHz
100 kft ± 1%; shunted by 270 pF^
each side to ground. Selectable
600-1501 O (± 1 %) terminations.
Maximum Rated Input
200 Vpeak, 140 Vrms on main inputs;
100 Vpeak on auxiliary input.
1 Watt (+ 30 dBm) with terminations.
Rejection Ratio
70 dB, 50 Hz-20 kHz, Vin «= 2V;
50 dB, 50 Hz-1 kHz, v in >2 V
300 jxV2-160 Vrms (6 dB steps
above 80 mV, 12 dB steps below 80
mV). Autoranging is peak sensitive
to prevent clipping with high crest
factor signals.
±0.1 dB (1%), 20 Hz-20 kHz
Response Flatness3
± 0.03 dB, 20 Hz-20 kHz;
±0.1 dB, 10 Hz-120 kHz;
+ 0.2/-3 dB to 500 kHz
Residual Noise
(input shorted)
1.5 |xV (-114 dBu), 22 Hz-22 kHz;
3.0 |xV (-108 dBu), 22 Hz-80 kHz;
5.0 JJLV (-104 dBqps), Qpeak CCIR-wtg
Specify option 11EURZ" to substitute 300 O for the
15012 termination selection.
80 mV-160 Vrms for LEVEL meter
V1n ^ 5 % of range, rms and average detectors only. Peak
detectors are +0.2/-0.3 dB, 30 Hz-100 kHz.
Typical bandpass and bandreject responses at 1 kHz.
Typical residual bandpass noise vs frequency input shorted.
10 Hz to at least 500 kHz
Ttmebase Accuracy
0 003%
6 digits+0 0002 Hz
Reading Time
Determined by the nearest integral
number of signal periods greater
than the reading rate sample time
(See Detector Characteristics)
Minimum Input
10 mV ( 38 dBu) useable to <1 mV
THD + N mode is similar to the Bandreject mode but with auto
nulling and fine tuning loops activated to maintain optimum
f jndamental rejection With FIXED tuning the notch frequency
ay be directly programmed (± 3% tracking range) for quan
azation distortion or 5INAD tests With AUTO tuning the notch
frequency is ganged to the GEN 1 module frequency during a
generator sweep otherwise it will track the measured input
frequency (provided V n ^10 mV and signal THD + N ^20%)
THD + N may be displayed as a ratio (% dB PPM X/Y) of the
total input signal measured by the LEVEL meter or as an abso
lute amplitude (Volts dBu dBm etc)
Fundamental Range
10 Hz 200 kHz
Minimum Input
<25 JJLV ( 90 dBu) with FIXED tuning
Typical residual THD + N vs amplitude, at 1 kHz. Upper trace
is with full measurement bandwidth O500 kHz);
center trace is with 22 Hz-80 kHz bandwidth limiting; bottom
trace is with 22 Hz-22 kHz bandwidth limiting.
10 mV ( 38 dBu) with AUTO tuning
THD+ N Range
Residual THD+ N5
0 to 100%
± 0 5 dB for harmonics to 120 kHz
+ 0 5 / 3 d B to 500 kHz
20 Hz 20 kHz
0 0010%+1 5 |iV 22 Hz 22 kHz BW
0 0015%+3 0 |xV 22 Hz 80 kHz BW
0 0040%+10|xVfullBW
<0 0010% at V n = 2Vrms
22 HZ 80 kHz BW
1OHZ 100 kHz
Auto Nulling Time
0 010% + 10(ULVfUlIBW
Typically 0 3 0 4 sec above 100Hz
1 5 sec at 20 Hz 3 5 sec at 10 Hz
A 20 Hz 20 kHz 16 point sweep will
typically run in 9 11 sec (8087 co
processor installed in computer)
lnput must be 52=10 mV with a ratio unit selection.
Typical residual THD + N vs frequency 22 Hz-22 kHz limiting.
Upper trace is with 3.0 V input; bottom trace is with 2.0 V
input. (Performance with other input amplitudes 300 mV
will typically fall between these values.)
5ystem specification including THD + N contributions from the
generator (20-25 Hz derated near maximum output). The analyzer contribution is mainly noise with THD typically <0.0004%/
10 Hz-20 kHz.
Typical residual THD + N vs frequency
22 Hz-80 kHz limiting. Upper trace is with
3.0 V input; bottom trace is with 2.0 V
input. (Performance with other input
amplitudes < 300 mV will typically fall
between these values.)
* "a'
Five detector selections are available with the principal READING meter rms, average, true peak, G-peak (per CClR Rec
468-3), and S-peak (scaled peak to read rms with sinewaves)
The LEVEL meter detector is rms only All detectors are linear
with signal crest factors up to 7
Channel A
Buffered version of channel A input
signal following attenuation and/or
pre amplification 3 Vpp maximum
Rout = 560(1 ± 5%
Channel B
Buffered version of channel B input
signal following attenuation and/or
pre amplification 3 Vpp maximum
Rout = 56011 ± 5%
Reading Signal
(Processed Signal)
Buffered version of the final (Pro
cessed Signal) signal presented to
the detector stages following all fil
tenng and additional gain stages
3 Vpp maximum Rout = 560 ohm
Reading rate selection determines the sample time of the
measurement, and minimum recommended frequency for
specified accuracy/stability
Reading Rate
Sample time
32 8 msec
65 5 msec
131 msec
262 msec
Minimum frequency
50 Hz
30 Hz
20 Hz
10 Hz
Total measurement time is the sum of the sample time plus an
additional 10 30 msec for data transfer and processing
Full measurement bandwidth is typically 4 Hz 600 kHz in the
AMPLITUDE mode, 6 Hz 600 kHz in the THD+N and BANDREJECT
modes Measurement bandwidth can be limited by indepen
dent high pass and low pass filters, or an external filter Up to
five option filters may also be installed for weighted noise or
other special measurements (see OPTION FILTERS)
High pass Filters
400 Hz ± 5%, 3 pole Butterworth,
100 Hz ± 5%, 3 pole Butterworth,
22 Hz, 3-pole Within CCIR 468-3
limits for unweighted response
Low-pass Filters
80 kHz ± 5%, 3-pole Butterworth;
30 kHz ± 5%, 3-pole Butterworth;
22 kHz, 6-pole within CCIR 468-3
limits for unweighted response
SYS 22 and SYS 02 configurations add a second autoranging
Channel B input and phasemeter enabling simultaneous
measurement of both input amplitudes ratio or crosstalk All
analyzer specifications valid for either input The 2 CHANNEL
and 'CROSSTALK' measurement modes route the selected
input channel through the main measurement path and the
alternate (reference) channel to the LEVEL meter and fre
quency counter CROSSTALK mode additionally processes the
selected input channel through the 1/3 octave bandpass filter
automatically tuned to the reference channel frequency (or
generator frequency)
±180° or 0-360°
Phase rotations beyond
-180/ + 360° can be accumulated
during sweeps
0.1° displayed. (Measurement
quantization is 0.013° at M/sec";
varying to 0.10° at vv32/sec")
± 1 °, 20 Hz-20 kHz;
±2° / 10Hz-50kHz
External Filter Connections
560 O ± 5%, unbalanced. Maximum signal level is 700 mVpp (-10
1 Meg O ± 5%, unbalanced. Protected up to 15 Vpeak overloads.
Bandwidth is >200 kHz.
Ratio Accuracy7
Crosstalk Accuracy7
Input Crosstalk
(R5 <600 O)
10 Hz-20 kHz
20 kHz-100 kHz
± 0.1 dB, 20 Hz-20 kHz;
±0.2plB, 10Hz-120kHz.
(Typically 0.03 dB on same ranges)
±0.7 dB, 20 Hz-120 kHz
The greater of:
-14OcJBOM jmV(-118 dBu)
-126 dB or 2.5 JJLV (-110 dBu)
Both input signals between 10 mV-8 Vrms. Above 8 Vrms
accuracy's ±1°, 20 HzSkHz; ±2°, 10 Hz-20 kHz; ±3°to50kHz
Typical responses of the bandwidth limiting filters.
Alternate channel signal must b$ ^10 mV
"C-Message" Weighting Filter CFIL-CMS)
Up to five option filters can be installed in the System One
analyzer for weighted noise or other special measurements.
Option filters function with the principal READING metei; and
can be enabled (one at a time) in series with the standard
bandwidth limiting filters.
Contact Audio Precision for quotations concerning other possible filter designs. Custom designs may be constructed on the
FIL-USR blank card. However please note that the system autoranging is based upon the peak value of the unfiltered signal
and will limit the maximum useable dynamic range to approximately 5OdB.
1/3-Octave Bandpass Filter CFBP-xxxxx)
Contact Audio Precision or your Audio Precision distributor for
complete specifications on option filters.
75 ixsec De-Emphasis + 15.734 kHz Notch Filter CFIL-D75B)
XClR" Weighting Filter CFIbCCR)
XCiTT" Weighting Filter CFIL-ClT)
W! Weighting Filter CFlL-AWT)
C" Weighting Filter CFiL-CWT)
15 kHz and 20 kHz Precision Bandwidth Limiting Filters
75 ixsec De-Emphasis + 19.0 kHz Notch Filter (F1L-D75F)
200 Hz-15 kHz Receiver/Tuner Bandpass Filter CFlL-RCR)
The IMD Option enables mtermodufation distortion measurements to all three of the most popular methods SMPTE Cor DIN},
DIM (or TSM), and CCF difference frequency IMD testing can
reveal important forms of non-linearity that are not easy to
detect with conventional THD/THD + N tests
The SMPTE test measures the amount of amplitude modulation of a high frequency tone caused by the presence of a
relatively low frequency tone The SMPTEIMD test is extremely
sensitive to frequency independent non-linearities such as
non-ohmic connectors, A/D-D/A problems, and other simple
transfer function deviations
The DIM (or "dynamic intermodulation") test measures nonlineanties that can be provoked by the rapidly slewing portions
of a combined sine-squarewave test signal This form of IMD is
quite common in certain operational amplifiers and systems
employing large amounts of negative feedback SMPTE and
DIM are good complementary tests of feedback amplifiers
because many designs will often trade off one form of distortion for the other Only the very best equipment exhibits simultaneously low SMPTE, DIM, and THD + N distortion factors
The CClF difference frequency test measures the amount of
2nd-order (or difference frequency) distortion that is caused
by two closely spaced high frequency test tones It is sensitive
only to asymmetric forms of non-linearity and is an excellent
test of transfer function symmetry
Minimum Input
10 mV
IMD Range
± 1 dB, for indicated IMD products
Residual IMD2
o 0018% SMPTE,
0 0020% DIM,
0 0005% CCIF
Test Signal
IMD Measured3
DIM Mode
Test Signal
IMD Measured4
The System One IMD option consists of two circuit boards. The
analyzer option board (IMD-DiS) mounts to the DlS-I distortion
measurement module.The generator option board (IMD-GEN)
mounts to the main generator module, it contains the SMPTE
and CCIF iM-frequency generator and the DIM test signal
squarewave generator The main oscillator of the generator
module provides the HF tone for SMPTE, probe tone for DIM,
and the carrier (or center frequency) for CCIF signals.
Test Signal
IMD Measured5
40-500 Hz (LF) mixed with
3-200 kHz (HF), any ratio
from 01 to 81 (LF HF)
40-500 Hz amplitude modulation
products of the HF tone Measurement bandwidth is typically 30 Hz700 Hz, however the tunable 1/3octave bandpass filter may be
used for improved sensitivity or
analysis of individual products
2 96-318 kHz squarewave mixed
with 4-100 kHz sinewave, 41 peakpeak
Ail products in the 750 Hz-2 40 kHz
band, expressed relative to the
amplitude of the sinewave tone
Measurement bandwidth is 400 Hz
2 45 kHz, however the tunable 1/3octave bandpass filter may be
used for improved senstitivity or
analysis of individual products.
Two equal amplitude 4-200 kHz
tones with 80 Hz-1 kHz separation.
Difference frequency product only
expressed relative to the amplitude
of either test tone. Measurement
bandwidth is always 1/3-octave.
Test Signal Modes
SMPTE1:1, SMPTE4:1, CCiF^ DlM-30,
DlM-IOO1 and DlM-B
Amplitude Range
<70 ixVpp to 75.40 Vpp
^Complies with SMPTE TH22.51 and DlN 45403.
Selectable 40,50,60,100,125,250,
or500Hz,all ± 2 %
Selectable 80,100,120,200,250,
500, or 1 kHz, all ± 2%
technique suggested by Paul Skritek of the Technical University
—Vienna, Austria. For more information see "Simplified Measurement of Squarewave/Sine and Related Distortion Test
Methods" by PSkritek, a paper presented at the 1985 Audio
Engineering Society convention in Hamburg, Germany (preprint
2195); and "Practical Extended Range DIM Measurements" by
Bruce E. Hofer, a paper presented at the 1986 AES convention
in Montreux, Switzerland (preprint 2334).
CClF Difference
DIM Squarewave
3.15kHz (DIM-30 and DIM-I00)or
2.96kHz (DIM-B), ±1%. Squarewave
is bandwidth limited with a 1-pole
filter at 100kHz in DlM-100 mode
and 3OkHz in DIM-30/DIM-B modes.
Balanced output mode only Divide maximum amplitude by
2 (-6 dB) for unbalanced output mode. Amplitude is calibrated
in Vpp. Other units are referenced to an equivalent sinewave
with the same peak-peak amplitude.
5ystem specification including contributions from both generator and analyzer Valid for inputs ^200 mV and test signal
frequencies to at least 20 kHz.
Complies with IEC 268.3 and IHFA202 recommendations for
the difference frequency product. Odd order IMD products are
not measured.
The Audio Precision Wow & Flutter Analyzer Option adds the
capability to measure rotational wow & flutter in accordance
With IEC 386, DfN 45507, CCfR 409-3, NAB, ANSf C16 5 (1971), JfS
5551 standards, and scrape flutter using the technique developed by Dale Manquen of Altair Electronics, lnc (Thousand
Oaks, California USA) Rotational wow & flutter is typically characterized by FM products in the 0 5-200 Hz range Scrape flutter is caused by fnctional effects of the tape sliding over
guides or the tape heads and is characterized by FM products
extending to 5 kHz, often peaking near 3 kHz
To measure wow & flutter a pre-recorded test tone of 3 0 kHz or
315 kHz is played-back into System One, where it is routed to
an FM discriminator located on the option board The discriminator generates a signal proportional to instantaneous frequency deviation It is passed through a weighting or
bandwidth limiting filter before detection All of the standards
recommend the weighting curve "B-C" shown below This provides measurements that correlate with the human ear's senitivity to the various FM products Unweighted measurements
employ the response shown by curve "A-E" exhibiting a controlled bandwidth from approximately 0 5 Hz to 200 Hz
sweeps for ch^rf-recorder-fe ptofs W 6 ^ i f e m # w i l | l | Xf
graphed simultaneously permitting both speed error Cdnft)
and wow and flutter measurements on the same graph Up to
three different parameters can be displayed as bargraphs, for
example, wow andflutter;speed erroi; and input level The MAX
and MlN hold features are useful in determining worst case
readings over a time interval
System One DSP configurations can perform FFT spectrum
analysis of wow and flutter to 0 06 Hz resolution The graphic
cursor in the example below shows the frequency of the domi
nant component, from which the diameter of the defective
part can be calculated
Test Signal
Minimum Input
Detection Modes
Wow & Flutter analyzer selectable responses. "B-C" is weighted,
A-E" is unweighted, "D-F" is scrape, and TV-F" is wideband.
(Ideal response data graphed using standard System One
Scrape flutter must be measured using a higher test tone
frequency such as 12.5 kHz to permit the discrimination of FM
products up to 5 kHz without aliasing. A slightly lower test frequency such as 10.0 kHz may be desirable when testing
sharply bandwidth-limited systems such as video tape
recorders (VTRSl The Audio Precision wow & flutter analyzer will
accept any test signal frequency in the 10.0-13.0 kHz "highband". Usable scrape flutter measurements can be made
with test signals as low as 8.0 kHz, however aliasing of any FM
products above 4 kHz will occur
Scrape flutter is measured using the response selection "D-F"
and is sensitive only to FM products above 200 Hz. Comparing
the below-200 Hz and above-200 Hz FM contributions is a
useful troubleshooting aide in servicing professional grade
tape recorders. A good machine will exhibit similar readings
for two different ranges. The wideband response selection
7\-F" covering the entire 0.5 Hz to 5 kHz range permits a single
rapid check of total flutter performance.
Option circuit board mounting to
the LVF-1 module.
2.80 kHz-3.30 kHz, or
10.0 kHz-13.0 kHz ("high-band") for
scrape flutter measurements)
10 mV (-38 dBu)
Response Selections
Residual W&F
4 Hz bandpass per IEC/DIN/NAB
0.5 Hz-200 Hz
200 Hz-5 kHz
0.5 Hz-5 kHz
± (5% of reading + 0.0005%)
0.001 % weighted;
0.002% unweighted;
0.005% scrape or wideband
Wow and flutter units selection includes %, dB, and PPM (partsper-million) units with displayed resolutions of 0.0001%, 0.01 dB,
or 0.1 PPM respectively. The design architecture features a single internal measurement range for optimum speed and
rapid recovery from the transients associated with tape
!Operational with "high-band" test signals of 10.0-13.0 kHz only.
Upper -3 dB rolloff is typically 4.5 kHz using a 12.5 kHz test
The standard Audio Precision System One software allows
wow & flutter measurements to be displayed in three different
formats: direct digital readout, "analog" bargraphs, or time
WFf TWf^
Option %xBmft adds burst, noise, and squarewave signal selections to the System One generator Typical applications include
dynamic signal processor testing, absolute polarity testing,
acoustic response measurements using noise, loudspeaker
efficiency measurements, and investigating amplifier or transducer transient response
The tone bursts are generated by synchronously gating the
generator main osaliator at zero crossings The number of ON
cycles, repetition interval, and OFF level relative amplitude are
all programmable The repetition interval can be expressed in
total number of cycles, time, or bursts-per second A front
panel input is additionally provided for triggering individual
bursts or gating the smewave from an external signal
Noise signals include white, pink, bandpass, and equalized
bandpass All of the noise signals are based upon a digital
white noise generator with a choice of pseudo-random (0 262
sec sequence length) or true random modes Both modes
feature excellent conformity to the ideal Guassian distribution
The white noise signal is lowpass filtered at 22 kHz to maximize
its energy within the audio bandwidth The pink noise signal
contains energy over an extended bandwidth of 10 Hz-200 kHz
with -3 dB/octave response characteristic The bandpass noise
signal is obtained by passing pink noise through a tunable 2pole constant Q filter with approximately 1/3-octave
bandwidth All noise signals may be gated via the front panel
trigger/gate input
The squarewave signal is optimized for general purpose time
domain testing of audio equipment It features a controlled
2 fxsec nsetime, very low energy content above 500 kHz, and
excellent symmetry Even harmonic components are typically
below 7OdB
Frequency Range
20 Hz-100 kHz
Amplitude Range
<70 fxVpp-37 70 Vpp
ON Cycle Range
1-65534 cycles Programmable in
cycles, sec, or %-ON
Interval Range
2-65535 cycles Programmable in
cycles, sec, or Bursts/sec
0 dB to <-60 dB,
± 0 5 dB, 20 Hz-20 kHz
OFF" Amplitude
Range and Accuracy
Spectral Modes
Bandwidth limited 10 Hz-200 kHz
Bandwidth limited 10 Hz 22 kHz
1/3 octave (2-pole) filtered pink
noise, continuously tunable or
sweepable, 20 Hz-100 kHz
Amplitude Range12
<70 fxVpp-37 70 Vpp
Typical Crest Factor
Pseudo-random Cycle
0 262 sec, synchronized to the
M/sec" analyzer reading rate
Frequency Range
Amplitude Range
20 Hz 20 kHz
<70 fxVpp 37 70 Vpp
Typically 2 fjisec
Unloaded (open circuit). Divide maximum amplitude by 2
(-6 dB) for unbalanced or common-mode configurations.
Amplitude is calibrated in Vpp. Other amplitude units are referenced to a sinewave with equivalent Vpp.
Noise amplitude calibration is approximate only, and may be
exceeded 0.01% of the time.
The DCX-127 muiti-funcuon module contains an autoranging
4-1/2 digit voltmeter ohmmete^ two 20-bit programmable dc
voltage sources, 21 bits of digital I/O, and three 8 bit program
mable auxiliary output ports for device control or status indica
tors Typical applications tnclude A/D and D/A converter testing,
VCA gain control linearity VCA distortion, amplifier dc offset and
power supply checks, power amplifier load switching control,
loudspeaker voice coil resistance measurements, tern
perature measurements and test fixture control
The meter features 200 mV 500 V and 200 O 2 Mil ranges,
fully floating and guarded for accurate measurements in the
presence of large common mode voltages Resistance mea
surements can be made using euher rhe 4-wire or 2-wre Technique. Readings cen be ofrsec and scaled ty cho System One
PftOGRArji CGm®0:. (W?UT/OUr?U7
inpuc Cwftgufacion
The two independently programmable dc sources have a
± 10.5 V bipolar range with 20 yM resplution and monotonicity
to 40 |xV (19 bits). Either dc source can be swept by the System
One software.
The DCX-127 also contains a simplified 8-bit program control
interface that can be defined to execute any pre-defined keystroke sequence. This can be used to run different software
procedures based upon switch closures.
Output Configuration
Pin 1
Pin 2
200 mv range
2 V range
?0 V range
i00 V range
500 V range
6 rdg/sec
0.05% +
0.05% +
0.05% +
0.05% +
0.05% +
25 rdg/sec
0.03 mV
0.1 mV
1 mV
10 mv
100 mV
0.05% + 0.1 mV
0.05% + 1 mV
0.05% + 1OmV
0.05% + 100 mV
0.05% + 1 V
Pin 3
Pin 4
Pin 6
Pin 7
8-£w parallel input lnpui bics are
software definable to execute any
valid keystroke sequence An 8-byte
FIFO buffer allows asynchronous
Delayed Gate High-low transition
occurs 50 msec to 12 75 sec (in 50
msec steps) after sweep start
Reset pulse, high during UTILITY
RESTORE command or following
power cycling to the DCX-127
2 msec pulse when data is settled
2 msec pulse at end of settling
Sweep Gate, low during sweeps
A/B Gate; high when LVF is measuring channel A
9-pin D-subminiature
200 mV-200 V
0.005% of range
500 V range
100 mV
Input Resistance
0.025% of range
22-bit (21 bits data + sign) words,
plus data valid/new data strobes.
25-pin D-subminiature connectors.
Maximum data rate
Approximately 8 msec/transfer; limited by computer speed
500 mv
10 Mft, ± 1 % (all ranges)
Common Mode Rejection >120 dB, at dc and 50 Hz-20 kHz
Common Mode Range
500 Vpeak
Normal Mode Rejection
>60 dB, 50 Hz-60 Hz
1 2
Accuracy *
200 ft range
2 kft range
20 kft range
200 kft range
? Mft range3
6 rdg/sec
25 rdg/sec
+ 0.04 ft
+ 0.2
4- 1
+ 10
+ 100
1 ft
10 ft
100 ft
1 kft
0.005% of range
0.025% of range
Three independent 8-bit parallel
output ports. 9-pin female D- subminiature connectors
All digital input/output is LSTTL/CMOS compatible. Outputs in
series with 39011 resistors. Input resistance typically 100 kft.
Maximum rated input 0-5V Output drive + 5mA/bit maximum.
17" W, 1.75" H, 10.5" D
Operating temperature
+ 5°C to + 400Q <80% RH
Overload Protection 100 Vrms continuous, + to - Input;
40 Vrms, either Source to Input
Power requirements
100/120/220/240 Vac (+ 5/-10%);
48-63 Hz; 20 VA maximum
Open Circuit Voltage
<6 Vdc
± 10.500 Volts (bipolar output)
20 JXV (20 bits equivalent)
±(0.05% + 0.2 mV), absolute;
± 40 s^y relative to best fit line
Maximum Output Current 20 mA source; 10 mA sink
Residual Noise
Output Floating
VaHd from + 15°C to + 300C <80% RH, for 1 year Derate linearly
to 2 times indicated values at + 5°C and + 400C
With both 2-wire or 4-wire configurations. When using 4-wire
configuration, lead resistance must he ^1.5 Ohms.
scale on the 2 Mft range is 2.50 Mil.
Load current must he ^l mA for specified accuracy. Output
resistance is typically <0. l ft.
<10 fxV RMS, 10 Hz-80 kHz BW
Electronically balanced to allow
low output (-) terminal to float up to
2 Vpk. Common mode rejection is
typically >54dB (500:1)
OSP (Digital Signal Processlngl ^ p a b l t t i y # l t | i n
System One Is available In t w o c o n f i g u r a t i o n —
System One + DSP™ and System One Dual Domain.™
System One + DSP adds the functions of waveform display
FFT spectrum analysis, individual harmonic distortion analysis,
and general purpose selective amplitude measurements for
analog domain signals
System One Dual Domain offers these same features plus
digital audio inputs and outputs in the professional AES EBU
format, consumer SPDlFEIAJ format, and 24 bit parallel format
Analysis capability in the digital domain includes wideband
and selective amplitude, 2 channel amplitude, weighted or
unweighted noise, THD + N, ratio, crosstalk, and frequency by
techniques directly comparable to traditional analog analysis
methods System One Dual Domain may thus stimulate and
measure in any of the four possible combinations of analog
and digital input and output
The specific function of the DSP module depends on DSP pro
grams which are furnished on diskette and downloaded from
the computer to the DSP module when desired Most DSP
specifications are thus program dependent DSP program
specifications follow the basic specifications
Sample rates
Analog source
Amplitude range
Accuracy, flatness
Worst-case harmonic or
spurious product
Signal Routing
Parallel I/O (System One Dual
Domain only)
Serial I/O (System One Dual
Domain only)
Two or three 24 bit 25 MHz third generation digital signal processors
32k x 24 bit (128k x 24 bit in System One Dual Domain or the MEM option). Actual data record
length depends upon DSP program in use.
8k X 24 bit
Dual channel independent 16 bit
192k (80 kHz analog bandwidth), 176.4k (80 kHz bandwidth), 48k (22 kHz bandwidth), 44.1 k (20 kHz
bandwidth), 32k (15 kHz bandwidth), or 1 k sample/second (350 Hz bandwidth). See the figure for
typical frequency response at each sample rate. Not all sample rates are available with all DSP
Selectable A-monitor output, B-monitor output, Reading monitor output (analyzer output), generator monitor output, or front panel dc-coupled fixed-sensitivity inputs.
Direct inputs
input via Analog Analyzer
2.00 Vrms full scale (2.828 Vpk)
300 fxV to 160 V rms, autoranging
± 0.25 dB dc-(0.45 x sample rate) at
± 0.25 dB 20 Hz-(0.45 x sample rate) at sample rates
sample rates ^ 8 kHz; for example,
^ 8 kHz; for example, 20 Hz-20 kHz @ 44.1 kHz sample
dc-20 kHz @ 44.1 kHz sample rate
- 90 dB for in-band signals « 0 . 5 x sample rate); - 60 dB for out-of-band signals
16-bit, slaved to A/D sample rate.
From front panel dc-coupled output, or through analog generator transformer-coupled output
24 bit dual channel available on two 34 conductor connectors on rear panel (one for input, one
for output). Channels are multiplexed on each connector Data rates are selectable 32k, 44.1 k, or
48k. Data strobe is included or may be externally supplied.
Supports the full implementation of the AES/EBU digital interface. 20/24-bit data, parity validity
and channel status bits are provided. The user bits are not supported. Electrically compatible
with the Sony Philips Digital Interface (SPDlF) and ElAJ interface. The transmitter and receiver
may operate at 32k, 44.1 k, or 48k. The transmitter may be slaved to the received signal, internal
clocks, or house synch.
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
I • Tfieftmcaon of me mpmmu$m^m^<MMpmmmU£B^
program is downloaded from computer disk to DSP unit initially four DSP programs are available HARMONIC DSP to perform individual harmonic analysis and other selective wave
analyzer functions, FFTGEN DSP and FFTSLIDE DSP for waveform display (time domain) and spectrum analysis (frequency
domain) via fast Fourier transform, and CENANLR DSP for generation and analysis of signals directly in the digital domain
Only FFTGEN DSP and GENANLR DSP include sinewave generation capability
Direct D-A Output
Through Analog
Generator Output
Digital Output
Range vs Sample Rate
10 Hz-15 kHz @ 32 kHz; 10 Hz-20.67 kHz @ 44.1 kHz; 10 Hz-22.5 kHz @ 48 kHz
(Sample Rate) /224 (approx. 0.003 Hz @ 48 kHz rate)
Fixed, 2.00 Vrms
26.66 Vrms to <25 |xV
rms (same as analog
Full 24 bit amplitude
1/216 (approx 30 fxV)
<0.01 dB or 1.27 ^V1
whichever is greater
1 LSB (1/224)
Flatness and Accuracy
± 0.25 dB 20 Hz-20 kHz @ sample rate
2*44.1 kHz
(FS = digital full scale)
same as analog
(FS = digital full scale)
- 9 0 dB for in-band signals « 0 . 5 x sample rate);
- 6 0 dB for out-of-band signals
Unbalanced, single
A&B7 A&-B(sameas
analog generator)
parallel; A, B7 A&B
Source impedance
50/150/600 ft (same as
analog generator)
110 ft AES/EBU7 75 ft
SPDIf= 22 ft parallel
Worst harmonic/spurious signal
Triangular or rectangular probability distribution
± 16th bit
Selectable from ± 1
LSB of 8 bit word
through 24 bit word
or OFF
FFTCEN DSP and FFTSItDE DSP are programs fat acqttetfj&i of \
waveforms and either waveform display or fast Fourier transform and spectral display FFTCEN includes a digital sinewave
generator function (specifications above), can average FFTs for
noise reduction purposes, and has modest triggering
capability when acquiring signals FFTSLIDE features more
powerful and flexible triggering including pre-tnggei; plus the
ability to perform an FFT starting at any selected point in the
stored signal Both permit high-resolution FFTs with up to 8,192
spectral lines (bins), providing resolution of about 3 Hz at the 48
kHz rate and 0 06 Hz at the 1 kHz rate for wow and flutter
Standard memory
Duration @ 192 kHz
Duration @ 48 kHz
Duration @ 32 kHz
Duration @ 8 kHz
Duration @ 1 kHz
Maximum memory (MEM option or
System One Dual Domain)
Duration® 192 kHz
Duration @ 48 kHz
Duration @ 32 kHz
Duration @ 8 kHz
Duration @ 1 kHz
8,192 samples/channel
0.043 sec
0.171 sec
0.256 sec
1.024 sec
6.144 sec
30,720 samples/channel
4,096 samples/channel maximum
0.021 sec
0.085 sec
0.128 sec
0.512 sec
4.096 sec
16,384 samples/channel maximum
0.160 sec
0.640 sec
0.960 sec
3.840 sec
24.576 sec
0.085 sec
0.341 sec
0.512 sec
2.048 sec
16.384 sec
All analog or digital input sources, analog
generator sync, power line
+ or—
Channel 1 or 2 signal, which may be any
analog or digital input source
(Sample rate)/(FFT input data length); for example, 48 kHz sample rate and 16,384
samples gives 2.93 Hz resolution (bin width)
1,4, or 16x
Direct Inputs
Input via Analog Analyzer
Accuracy Flatness
Depends upon frequency separation of signal component from center of bin. Worstcase errors are 0.8 dB for BH4 window, 1.5 dB for Hann, and 4.5 dB for "flat" (no window)
Units (%FS & dBFS also available for anal-
V, dBy dBi; dBm, dBu, W
V dBy dBi; dBm, dBu, W1 %, dB, PPM, X/Y
± 1 degree to 50 kHz
± 2 degrees to 50 kHz
ysis of digital signals in Dual Domain units)
Signal Acquisition Time
see RECORD LENGTH/Duration above
Transform, Windowing, and Magnitude
Transfer to computer and display
typically 600 msec for 16,384 samples; 165 msec for 4,096 samples; 50 msec for 1,024
depends on number of points plotted, computer processor type, clock rate, coprocessor type of display system. For 20 MHz 80386 with 80387 co-processor color
VGA, 512 points plotted, typical time is 2.2 seconds
HA*M J N •-Da-ar....... >-*, j j s
; HARMONICOSPisdreal-time ptmmtnptm^vfgimqmmyrselective amplitude measurements of analog signals A tunable bandpass filter may be steered by a panel entry by the
analog generator frequency or by the analog analyzer band
pasc-bandr eject filter frequency
that frequency or offset by a user-entered value above or
below that frequency A DSP implemented RMS detector fol
lows the filter
Harmonic Analysis
Direct Input
Input via Analog Analyzer
V dBy dBi; dBm, dBu, W
V dBy dBr; dBm, dBu, W, %, dB, PPM, X/Y
Sample Rate ^ 4 8 kHz
Sample Rate ^176.4 kHz
10 Hz 2177 kHz © 4 8 kHz,
10 Hz 20 0 kHz @ 441 kHz,
10 HZ 14 5 kHz @ 32 kHz
Filter Shapes
1/8 octave (Q = 12, - 3 dB BW 8% of center
frequency) or 1/10 octave (Q = 15, - 3 dB
BW 6 7% of center frequency)
1/8 octave (Q = 12, - 3 dB BW 8% of center
Filter Steering
Steering source software panel entry or analog generator frequency or analog ana
lyzer BP/BR filter frequency Filter can track directly at source frequency or at selectable
harmonic 2 9 of source frequency or at panel entered frequency offset above or
below source frequency
GENANLR.D5P is a real-time digital input/output program
designed for use only with System One Dual Domain. It
acquires digital-format audio data on two channels simultaneously has two DSP-implemented RMS detectors, and
offers a selection of filters including tunable bandpass, tunable bandreject, and A-weighting and CCIR weighting filters plus
a quasi-peak detector for noise measurements. It thus emulates in the digital domain most of the common analog
domain audio measurements.
AES-EBU, SPDIF-ElAJ, P a r a l l e l . 2 c h a n n e l s , 2 4 b i t s
Accuracy & Flatness
O d B F S t O - 1 2 5 dBFS
±0.01 dB
± 0.02 dB
Filter Shapes
Bandpass (Q = 15), bandreject, BR+ 400 Hz Hf?400 Hz HF? A-weighting, CCIR weighting
Bandpass Frequency Range
0.04% to 40% of sample rate; for example, 20 Hz-19.2 kHz @ 48 kHz sample rate
Bandreject Frequency Range
0.1 % to 40% of sample rate; for example, 50 Hz-19.2 kHz @ 48 kHz sample rate
Residual THD+ N
%FS, dBFS, BITS, dB (ref LEVEL measurement)
5 Hz to 40% of sample rate for rated accuracy
Maximum of 0.003% of reading or 0.0001 % of sample rate
0.01 % of reading or 0.0001 % at 4 readings/second
The SWR-122 line of audio switchers can connect System One
to a wide variety of devices under test All connections to mujti
track recorders, routing switchers, distribution amplifiers, mix
ing consoles, or multiple units may be made at one time and
the complete device characterized without operator interven
tion In production board test applications the switchers may
be used to access multiple points in the circuit under test The
Series 122 switcher family is available in four versions
• Input switcher with XLR connectors (SWR 122F)
• Output switcher with XLR connectors (SWR 122M)
• Patch point switcher with XLR connectors(SWR 122P)
•Connectorless, terminal strip version (SWR 122T) which can
be configured in any of the above three functional types
Figure 1. Simplified diagram of input or output versions.
Al! four of the Series 122 switchers use the same circuit board.
They differ from one another in connector configuration and in
attributes set by internal jumpers, which define them as an
input switcher; output switcher; or a patch point switcher
Each of the switchers is a 12 by 2 relay matrix. Either common
point can be connected to any of the twelve selectable points.
All the switchers are of balanced design but may be used with
unbalanced circuits. Input switchers expand input channels
above the two available in the dual channel System One. Output switchers expand output channels. Output switchers also
permit measurement of worst-case crosstalk by driving all but
one channel. System One may control up to 16 Input switchers
(192 channels) and 16 Output switchers (192 channels).
The Patch-Point switcher is both an input and output switcher
The front panel has twelve 5-pin XLR connectors plus one connector each for the System One generator output and analyzer input. The Patch-Point switcher is designed for insertion
between the output of one stage or device and the input of the
following stage or device. When a channel is not selected, the
device connections are looped through the switcher and no
connections are made to System One. When an input channel
is selected, the analyzer is bridged across the signal at that
point. If a channel is selected as an output, the "normalled
through" connection will be broken. The System One generator
can then drive the input of the following stage or device, and
the analyzer can measure the unloaded output of the preceding stage.Multiple points in a signal chain can be wired
through the Patch-Point switcher and measurements can be
made of any portion of the chain, under program control. A
simplified diagram of the Patch-Point switcher is shown in the
figure 2. Although a Patch-Point occupies both input and output spaces in the System One program, it may be configured
for either Channel A or Channel B operation. This allows two
Patch-Point switchers to replace an input and an Output
Figure 2. Simplified diagram of Patch Point version.
Max Signal Rating
200 V peak; relay contacts rated to
switch up to 60 Watts or 2 Amperes
-134 dB to 20 kHz;
Series Resistance
0.5 ft per side
Shunting Capacitance
Typically 90 pF each side to ground;
80 pF balanced
17" W x 1.75" H x 10.5" D;
mounts within standard rack
unit with supplied brackets
Temperature Range
+ 5°C to + 400C, operating
Power Requirements
90-126 or 180-250 Vac, 48-63 Hz;
12 VA max
!Measured between any two channels with 600 ft or lower
source/load resistance on the measured channel. The
crosstalk from the interrupted input to output on the the patchpoint switcher is typically 70 dB to 20 kHz.
System One nomenciature consists of
the letters SYS, two or three digits, and
the letter A, it ot € Thetefettwo digits
describe the number of audio outputs
and inputs For example, an SYS-22 has
two generator outputs and two analyzer
inputs The 200 series (SYS-222, etc)
features DSP capability for waveform
display FFT spectrum analysis, and individual harmonic analysis The 300
series (SYS-322, etc) adds digital audio
input-output capability to the 200 series
features 7\" describes the IBM-PC-compatible version which communicates
with the PC over the Audio Precision
Interface Bus (APlB) via a furnished interface card plugged into an expansion
slot "S", also PC compatible, is the serial
^ r 5 1 0 n requiring only an RS-232 port
describes the GPIB (IEEE-488) version "S" and UG" versions also have APlB
ports, but are not supplied with interface cards
IMD option adds an IMD generator and
IMD analyzer
W&F option adds the Wow & Flutter
BUR option adds the tone burst, square
wave, noise generator
To operate the TV' version from the IBM
PS/2 microchannel bus, specify the
MiCRO-CH option which replaces the
PCI-2 with the PCI-3 card SWR-122
switcher modules and the DCX-127 mul-
•fyscar one ope r a r -:s »-#rLn IBfZ-PC, .(T ^1
ar~d PS/2 c o m o u e i i and compatni?s,
i jnmncj - nrter DOS 3 '* o, l3rer i nesc
compucers a r e ceneraiiy based on
808¾ 8086,8028¾ or 803&6 microprocessors System One is in daily use with
dozens of different brands of compatibles including Compaq, Olivetti, AT&T
DeII7 Zenith, Tandy and many "clones"
640 kbytes memory size is required
System One is compatible with any
clock rate in the host PC Faster testing
results from computers with more
powerful processors and faster clock
rates An AT-compatible or faster is recommended for FFT and waveform display with System One DSP units A math
co-processor (8087,80287, etc) is
strongly recommended, especially with
the less powerful computers
tifunction module, when used with an A
version, connect in "daisy chain" fashion
with System One from the interface
card in the PC When SWR-122 and
DCX-127 modules are used with an S or
G version, they connect to the SYS unit
via the Audio Precision Interface Bus
The SYS unit is then controlled via either
RS-232 (S version) or IEEE-488 (G
this brochure; the S version must be
controlled from S1.EXE The G version is
normally controlled from Bh fEIEe-488
controller via user-wntten software,
using the extensive command set
For specialized applications over the
Audio Precision interface Bus, the
user may write custom software in the C
or BASIC languages The LIB-MIX function
library augments those languages with
over 160 functions providing complete
control of System One hardware LIBMIX is compatible with Microsoft C 5,
Microsoft QuickC 10, Microsoft QuickBASIC 4 0, and Lattice C 3
The A version is normally controlled
from the panel-menu graphic display
software (S1 EXE) described throughout
11 Qnniomrtniitcinniainnitt
Aversion with interface card
G ,EEE 488 v e r s i o n
20 Dual output! no analyzer
02 No generator, dual input
202 System One + DSP analyzer only
222 System One «+• DSP dual channel
302 System One Dual Domain, analyzer only
322System One Dual Domain, dual channel
S version
G version
System one software supports the full
resolution OfVGA7 CGA, and Hercules
high resolution monochrome display
systems Portable computers are rec
ommended for field and portable use
Desktop units typically provide larger
screens, color screens, and more
expansion slots when portability is not a
System One will operate with disk drive
configurations as minimal as one dis
kette, but is more convenient with two
'J.f-Vetie drives era \\^ec khardx d bk A
•vpica >£Si £&iuc v^n data 5iCres n
'ess ihan 2 Kbytes of disk space /> hard
diSv i i .ecommended ior saving *vavQ
forms from System One OSP unfe
System One's graphic hard copy
capability at screen resolution, is com
patible with Epson FX compatible dot
matrix printers and HP LaserJet printers
High resolution graphic hard copy is
available to HPGL plotters, suitably inter
faced HP LaserJet printers, and
PostScript laser printers such as the
Apple LaserWriter
Audio Precision team members are
active contributors to the technical
advancement of the audio industry
Contributions include technical papers
presented at Conventions of the Audio
Engineering Society Society of Broad
cast Engineers, National Association of
Broadcasters, SMPTE, Central Canadian
Broadcast Engineers, and International
Congress on Acoustics, plus seminars
and presentations at numerous chap
ter meetings of the AES, SMPTE, and
SBE Articles by Audio Precision staff
appear frequently in publications
including The Journal of the Audio
Engineering Society Broadcast
Engineering, Studio Sound, Sound &
Video Contractor Recording Engineer/
Producer; TV Technology and Radio
Audio Precision was formed in 1984 by
four former Tektronix engineers and
managers who had developed two
generations of high technology audio
test equipment for Tek.
Audio Precisions mission is uto be the
international technology and quality
leader in the audio test equipment
field". System One has brought automated testing to hundreds of companies where it was previously
excluded due to the large investment
required in programming or the inadequate performance levels previously
available. Audio Precision is uniquely
positioned by technical talents, experience, and size to serve the world's
audio testing needs.
Many audio workers still make measurements with equipment so laborious
in setup and operation that they can't
do as much testing as they would like.
Many use test instruments whose specifications are exceeded by much of the
equipment they measure. Many need
to test both digital and analog audio
equipment, but lack digital audio test
instruments. Many still prepare test
results with laborious hand techniques
of point by point plotting on graph
The Audio Precision team focuses
purely on audio testing applications.
Extensive use of computer modeling
and analysis expands productivity and
ensures stable, reliable products. All the
design team are broadly experienced
in both analog and digital design, and
both hardware and software solutions.
The results are optimum, balanced
designs with intelligent tradeoffs. Audio
Precision is committed to product quality reliability and usability under realworld conditions.
Bob Metzler, President. B.5. Physics, U.
of Louisville; M.B.A., U. of Portland. 11
years at Tektronix, principally as Marketing Manager of TM 500 and TM 5000
instrumentation lines which included
Tek<s audio test equipment products.
Author of numerous articles and
applications notes. Member AES.
Bruce Hofer, Vice-President/Principal
Engineer B.S.E.E., Oregon State University 15 years at Tektronix; program manager and contributing design engineer
for all audio test instruments and programmable power supplies. Design
engineer on timebases for 7000 series
oscilloscopes. Eleven patents. Numerous publications and presentations.
Member AES and American Scientific
Tom Mintner, Director of Sales & Marketing, U.S.A. B.Mus., Northwestern University; followed by fellowship and
professional staff position at University
of Iowa for diverse recording and Art &
Technology projects including laser
image projection systems. Active for 20
years as professional recording
engineer; as well as in applications
engineering, sales and management
positions with Neve and Studer Member; AES and the National Academy of
Recording Arts & Sciences.
DL Richard Cabot, Vice-President/
Principal Engineer B.S.E.E., M.Eng., M.S.
Mech, Ph.D.E.E., all from Rensselaer Polytechnic Institute. Registered Professional Engineer Six years at Tektronix as
project/design engineer on audio test
instruments. Author of over 35 papers/
presentations. Six patents. Fellow of
AES, senior member !EEE, member
Acoustical Society of America. International Regional VP of AES, member AES
Journal Review Board, Chairman of AES
Subcommittee on Digital Audio
Robert Wright, Vice-President/
Software Engineering. A.S. Computer
Technology American River College.
Additional studies at Case Western
Reserve Universities and University of
Portland. 6 years at Tektronix; project
leader for AA5001 Programmable Distortion Analyzer Programming experience
under UNIX and MSDOS, and in many
high level and microprocessor assembly languages. One patent pending.
Member; AES, ACM.
Debra Brimacombe, Applications
Engineer 2 years of university work
towards a B.S.E.E. degree. 10 years
experience in AM & FM commercial
broadcasting including Assistant and
Chief Engineer positions. Experienced in
all phases of broadcast maintenance
including proof-of-performance measurements and tape recorder alignment. Licensed amateur radio operator
, .,.., , , ,
Carl Hovey, Software Engineer B.S.E.E.
and M.S.E.E., Washington State University 9 years experience at Tektronix,
including firmware design for Programmable Distortion Analyzer Designed
architecture and hardware for 32 bit
microprocessor emulator Designed
polyphonic keyboard synthesizer as
thesis project. Member; AES.
Tony DaI MoIIn, Operations Manager
(Manufacturing, Materials, Quality Control). B.S.E.E., Massachusetts Institute of
Technology. 11 years experience in circuit
design, manufacturing, quality
assurance, installations for Biamp Systems, Neptune Electronics, Sundholm
Electronics. Developed pro audio signal
processing, sound reinforcement,
recording equipment. Member; AES and
Rick Swimrrt, Software Engineer;
B.S.C.S.E.T Oregon Institute of Technology Six years experience at Tektronix
designing firmware of programmable
signal generator; firmware and hardware on test interface product. Membet; AES and ACM.
Test equipment is normally purchased
for an expected lifetime of 7-10 years or
more After-sale support is an important
part of the product
on compact disk player t ^ t t n g and
loudspeaker testing are available Other
applications notes are planned on topics including analog tape machine test
ing, digital recorder testing, tape media
testing, and acoustical tests
The System One Users Manual is a 300page-plus document describing operation from initial installation through
sophisticated applications The Users
Manual is thoroughly indexed and
Applications packages include a diskette of specialized software and may
include specialized hardware. Examples include packages for BTSC (U.S.
stereo tv standard) system testing and
FM stereo broadcast equipment
Each System One is shipped with diskettes of sample tests, procedures, anc
other useful software. These tests can
be used to begin automated testing
instantly. They can be modified as
desired to fit vour soecific needs.
Audio Precision regularly publishes the
AUDIQTST newsletter This newsletter
contains articles on new testing techniques, describes new hardware and
software products and features, and
lists new literature. It offers a forum to
share testing ideas as users and Audio
Precision discover new ways to exploit
the capabilities of System One.
Applications notes are in-depth discussions of how to use System One for particular types of measurement. They
frequently have companion diskettes o
oreoared tests and procedures. Notes
peered sweeps, /---' c'' ,DI3./ O" 'I'VO r ^ c •
!r-j-eci pbra-^iers. od'o^Sr= sveepr
(spectrum mBk/$BfwBMy aS^atoBrty
(parameter passing from test to testy
remote control capability polarity test
mode, improved control of data settling,
data subtraction capability (analyzer
equalization), computation of deviation
from perfect linearity data smoothing,
2sigma computation for wow and flut
tei; and appending data from multiple
Audio Precision and its International distributors have experienced applications
engineers standing by for consultation.
Audio Precision can be quickly reached
by telephone (toll-free number available within the U.S.), FAX, or telex. A growing library of software utilities
supplements built-in computational
features of System One software. These
utilities can be run manually or automatically as part of a procedure. Utilities perform tasks such as calculating
group delay calculating linearity of a
Compact Disc player combining
selected data from different tests in
order to graph desired functions versus
one another; finding maximum or minimum values of a test run, averaging
data and generating limit files offset
from the average, etc.
Free software upgrades, consisting of
new diskettes and a new User's Manual
are furnished to all customers each
time the software is revised.
Most of todays key features have thus
become available even to customers
who purchased the very first units in
1985. Examples of powerful capabilities
added by software upgrades include
VGA and EGA display support, highresolution printout via plotters and lase
printers, sub-procedures, user-created
test menus, generator equalization,
Audio Precision warrants its hardware,
software, and firmware products for
three years against defects in materials
and workmanship. Audio Precision will,
at its option, repair or replace products
which prove to be defective during the
period. The foregoing warranty is
exclusive and no other warranty shall
be made by Audio Precision whether
express or implied. This warranty is subject to certain limitations and
restrictions set forth in Audio Precision's
terms and conditions of sale which will
be furnished to customers at time of
quotation or sale.
An Extended Warranty Policy is available within the U.S. to continue warrant\
coverage for an additional three-year
period; similar plans may be available
from Audio Precision International Distributors. An extensive service manual
can be purchased. This manual
includes schematic diagrams, parts
lists, exploded mechanical views, parts
location diagrams, discussions of theory of operation, and calibration procedures. It also includes a calibration
procedure diskette, which prompts a
technician through complete adjustments of System One with on-screen
drawings of test point and adjustment
locations and bargraph displays for
Standard tests and procedures furnished with all systems include a quick
performance check which can be run
as desired for an indication that Systen
One is performing properly
Audio Precision products are designed
around high quality components including low-noise integrated circuits, high
stability mica and polypropylene
dielectric capacitors, precision film
resistors, and ultra-high-rehability relays
with bifurcated, gold-plated contacts of
good wiping action sealed in a dry nitrogen atmosphere A custom Jensen
transformer is used in the generator
MDACs (multiplying digital-to-analog
converters) linearized by a patented
technique are used as variable control
elements, rather than drift-prone temperature-sensitive light dependent
resistors or distortion-introducing analog multipliers used in other designs
Raw circuit boards are continuitytested Completed circuit boards are
functionally tested before assembly
into units. Newly-assembled units are
again tested and pre-calibrated. A 7day burn-in follows at a temperature of
50 degrees Celsius Power is cycled at
one hour intervals during this period
This burn-in locates "infant mortality"
problems while the unit is still at Audio
Precision, rather than in the customer's
hands Units are then fully calibrated
using computer-assisted programs
similar to the calibration process furnished with the Service Manual
Accuracy of the test instruments used is
traceable to the U S National Bureau of
Standards Each unit then goes through
a completely automated test procedure which, on a fully-optioned system, consists of over 1,500
measurements Every measurement is
compared to Audio Precision's internal
specifications, which in most cases are
tighter than the specifications published in this brochure The results of
every measurement are stored on disk
for each unit
F, cm srs Oi :cjne! conception, Sysiem
One was designed for world (Markers
rilieis impedances, decectcy
responses, units of measure, and other •
~iuirements of European and Jap
ise standards were given equal
weight to U S methods One half of Sys
tern One sales have consistently been
outside the U S
Audio Precision distributors with trained
Sales Engineers, demonstrator instru
ments, and service facilities are located
in 23 countries System One is currently
in use in over 30 countries
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