Sound Performance Lab RackPack Modular Processing Rack Owner Manual

Manual
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Premium Mic Pre
RackPack Module, Model 2712
Single-channel microphone preamplifier module with I/O transformers
Manual Premium Mic Pre
Model 2712
Version 1.0 – 8/2007
Designer: Wolfgang Neumann
This user‘s guide contains a description of the product. It in no way represents
a guarantee of particular characteristics or results of use. The information in
this document has been carefully compiled and verified and, unless otherwise
stated or agreed upon, correctly describes the product at the time of packaging
with this document.
Sound Performance Lab (SPL) continuously strives to improve its products and
reserves the right to modify the product described in this manual at any time
without prior notice. This document is the property of SPL and may not be copied
or reproduced in any manner, in part or fully, without prior authorization by SPL.
SPL electronics GmbH, Sohlweg 55, 41372 Niederkruechten, Germany
Phone. +49 (0)2163 983 40
Fax +49 (0)2163 983 420
E-Mail: [email protected]
Internet: www.soundperformancelab.com
CE Declaration of Conformity
Manufacturer: SPL electronics GmbH, Type of Equipment: Audio
Signal Processor, Product: RackPack/Premium Mic Pre, Model 2712,
Compliance Engineer: Wolfgang Neumann
Test Basis: EN50081-1:1992, EN50082-1:1992, EN60065:1993, EN61000-33:1995, EN60065:2002, EN55013:2001, EN55020:2002, EN61000-3-2:2000,
73/23 EWG; 93/68 EWG. We herewith declare, that the construction of the
Premium Mic Pre, Model 2712, is in compliance with the standards and regulations mentioned above.
Notes on environmental protection
At the end of its operating life, this product must not be disposed of
with regular household waste but must be returned to a collection
point for the recycling of electrical and electronic equipment. The
“wheelie bin“ symbol on the product, user‘s manual and packaging indicates
that. The materials can be re-used in accordance with their markings. Through
re-use, recycling of raw materials, or other forms of recycling of old products,
you are making an important contribution to the protection of our environment.
Your local administrative office can advise you of the responsible waste disposal
point.
WEEE Registration: 973 349 88
© 2007 SPL electronics GmbH. All rights reserved. Names of other companies
and their products are trademarks of their respective owners.
2
RackPack: Premium Mic Pre
Contents
Important Security Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
Hook Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
Scope Of Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7
Rear Panel/Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XLR Sockets, Lundahl Transformers, Channel Split . . . . . . . . . . . . . 8
8
9
Control Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mic Gain, About Leveling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VU Meter, PPM, -10 dB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 V Phantom Power Supply, Pad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase Reverse, High-Pass Filter, Signal LED, Overload LED . . . . 10
10
11
12
13
Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Triple Stage Preamp, Stage 1 – The Input Transformer . . . . . . . . . . Stage 2 – The Discrete Differential Amplifier . . . . . . . . . . . . . . . . . . . . Stage 3 – The Instrumentation Amplifier,
Foil And Styroflex Capacitors, Outputs, Channel Split . . . . . . . . . . 14
14
15
16
Copy Master: Recall Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
CMRR, Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Guarantee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
RackPack: Premium Mic Pre
3
Important Security Information
Please note and retain this information. Carefully read and follow all
of the safety and operating instructions before you use the machine.
Be doubly careful to follow all warnings and special safety instructions
noted in this manual and on the unit. The following information refers
to modules built into the RackPack frame.
Connections: Only use the connections as described. Other connections can lead to health risks and equipment damage.
Water And Humidity: Do NOT use this machine anywhere near water
(for example near a wash basin or bath, in a damp cellar, near swimming pools, or the like). In such cases there is an extremely high risk of
fatal electrical shocks!
Insertion Of Foreign Objects Or Fluids: NEVER allow a foreign object
through any of the machine‘s chassis openings. You can easily come
into contact with dangerous voltage or cause a damaging short circuit.
NEVER allow any fluids to be spilled or sprayed on the machine. Such
actions can lead to dangerous electrical shocks or fire!
OPENING THE DEVICE: Open the device only to fit or exchange modules.
The fitting and/or exchange of modules should only be carried out by
qualified persons. In the light of possible physical damage or injuries
any manipulation is at your own risk. In order to avoid any residual
voltage, the device should be disconnected from any power source at
least 5 minutes prior to opening it. If you handle the device improperly
or ignore the manual (part of the delivery of the RackPack frame) you
risk to damage the device or expose yourself to an electric shock. In
these cases SPL electronics GmbH denies any responsibility.
Electrical Power: Run this machine ONLY from sources which can
provide proper power at the prescribed rating. When in doubt about
a source, contact your dealer or a professional electrician. To be sure
you have isolated the machine, do so by disconnecting the power cord
from your wall connection. Be sure that the power cord plug is always
accessible. When not using the machine for a longer period, make sure
to unplug it from your wall power socket.
Power Cord Protection: Make sure that your power cord is arranged
to avoid being stepped on or any kind of crimping and damage related
to such event. Do not allow any equipment or furniture to crimp this
power cord.
Power Connection Overloads: Avoid any kind of overload in connections to wall sockets, extension or splitter power cords. Always keep
manufacturer warnings and instructions in mind. Overloads create fire
hazards and risk of dangerous shocks!
4
RackPack: Premium Mic Pre
Important Security Information
Lightning: Before thunderstorms or other severe weather, disconnect
the machine from wall power (but to avoid life threatening lightning
strikes, not during a storm). Similarly, before any severe weather, disconnect ALL the power connections of other machines and antenna and
phone/internet cables which may be interconnected so that no lightning damage or overload results from such secondary connections.
Air Circulation: Chassis openings offer ventilation and serve to protect
the machine from overheating. NEVER cover or otherwise close off
these openings. NEVER place the machine on a soft surface (carpet,
sofa, etc.). Make sure to provide for a mounting space of 4-5 cm/2 inches when mounting the machine in racks or cabinets.
Controls And Switches: Operate the controls and switches only as described in the manual. Incorrect adjustments outside safe para-meters can lead to damage and unnecessary repair costs. Never use the
switches or level controls to effect excessive or extreme changes.
Repairs: Unplug the machine and immediately contact a qualified
technician when you think repairs are needed – or when moisture or
foreign objects may accidentally have gotten in to the housing, or in
cases when the machine may have fallen and shows any sign of having been damaged. This also applies to any situation in which the machine has not been subjected to any of these unusual circumstances
but still is not functioning normally or its performance is substantially
altered.
In cases of damage to the power cord or its plug, first consider turning
off the main circuit breaker before unplugging the power cord. Replacement/Substitute Parts: Be sure that any service technician
uses original replacement parts or those with identical specifications
as the originals. Incorrectly substituted parts can lead to fire, electrical
shock, or other dangers, including further equipment damage.
Safety Inspection: Be sure always to ask a service technician to conduct a thorough safety check and ensure that the state of the repaired
machine is in all respects up to factory standards.
Cleaning: In cleaning, do NOT use any solvents, as these can damage
the chassis finish. Use a clean, dry cloth (if necessary, with an acid-free
cleaning oil). Disconnect the machine from your power source before
cleaning.
RackPack: Premium Mic Pre
5
Hook Up
Fitting A Module
The fitting and/or exchange of modules should only be carried out by
qualified persons. Please read the manual of the RackPack frame. It
contains all information needed to fit a module as well as all safety
and notes and warnings. If you don‘t have the manual at hand, you can
download it like all SPL product manuals from our website http://www.
soundperformancelab.com.
Symbols And Notes
IN THIS MANUAL A LIGHTNING SYMBOL WITHIN A TRIANGLE WARNS
YOU ABOUT THE POTENTIAL FOR DANGEROUS ELECTRICAL SHOCKS
– WHICH CAN ALSO OCCUR EVEN AFTER THE MACHINE HAS BEEN
DISCONNECTED FROM A POWER SOURCE.
AN EXCLAMATION MARK (!) WITHIN A TRIANGLE IS INTENDED TO MAKE
YOU AWARE OF IMPORTANT OPERATIONAL ADVICE AND/OR WARNINGS
THAT MUST BE FOLLOWED. BE ESPECIALLY ATTENTIVE TO THESE AND
ALWAYS FOLLOW THE ADVICE THEY GIVE.
The symbol of a lamp directs your attention to explanations of important functions or applications.
Attention
Do not attempt any alterations to this machine without the approval
or supervision of SPL electronics GmbH. Doing so could nullify completely any and all of your warranty/guarantee rights and claims to
user support.
Scope Of Delivery
The scope of delivery comprises:
• The module
• This manual
• Four Philips screws to mount the module to the back panel (if module is delivered separately from the frame). Further screws needed
for mounting the module remain when you remove front and rear
covers from the RackPack frame.
6
RackPack: Premium Mic Pre
Introduction
When recording acoustic instruments or vocals, using a microphone
is inevitable. The actual output level of a microphone is very low and
therefore has to be boosted to studio or line level (0 dB) with a preamplifier. Sometimes signals have to be boosted by a factor of 2000 or
more. As a consequence, the resulting sound quality provided by the
preamp is of paramount importance, so a good microphone preamp
that does not overdrive is the definitive requirement in order to record
acoustic instruments or vocals with sufficient dynamics and untainted
sound.
The section “technology“ from page 14 explains how the Premium Mic
Pre complies with these requirements on the highest level and how it
delivers premium results even in difficult and critical set-ups.
Even the less technically interested users get an impression of the great
efforts it takes in development, circuitry design, selection of parts and
assembly to create a product on the Premium Mic Pre’s quality level.
From there we deduce a superior price/performance ratio – emphasizing on the performance which lends the Premium Mic Pre a world-class
sound quality.
Main Features
The Premium Mic Pre offers preamplification values of up to +80 dB
with lowest noise operation and a high common mode rejection.
Input stage and Output 1 are equipped with Lundahl Transformers
(High Performance Series).
A VU meter with two modes for average levels (VU) and peak levels
(PPM) displays the output levels.
A very stable phantom power supply (48V) is provided to power condenser microphones.
The polarity of the microphone can be switched with the phase reverse
switch.
A high-pass filter protects against low frequency interferences.
Two LEDs are placed into the VU window to concentrate all displays in
one area.
The signal LED indicates that an input signal is present, the overdrive
LED warns against potential overdrives.
RackPack: Premium Mic Pre
7
Rear Panel/Connections
Wiring
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RackPack: Premium Mic Pre
XLR Sockets, Transformers, Channel Split
Rear Panel/Connections
XLR Sockets
Connect your microphone to the transformer balanced XLR input.
The Output 1 of the Premium Mic Pre is transformer balanced, too.
Output 2 is electronically balanced. You can use both XLR outputs
simultaneously.
XLR pin wiring: Pin 1 = ground
Pin 2 = hot (+)
Pin 3 = cold (-)
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The illustration shows the correct pin
wiring of the balanced XLR sockets if
an unbalanced wiring is required.
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Lundahl Transformers
The input stage and Output 1 are transformer-balanced (for details
refer to “Technology” from page 14 cont.). Output 2 is electronically
balanced and can not be equipped with a transformer. Output 2 is decoupled actively to allow splitting the input signal over Output 1 and
Output 2.
Channel Split
Since the Premium Mic Pre provides two independent outputs, it always offers you two routes for one input channel.
If, for example, a RackPack is configured as a channel strip, one preamp output can feed the next module while the second output is used
to record the direct preamp signal.
Another exemplary studio application is to send one signal directly into
the A/D converter to be recorded in your DAW while the second signal
is used for latency-free monitoring (e.g. cue mix for the singer).
In live applications output 1 can be routed to the Front Of House (FOH)
while output 2 feeds the monitoring mixer.
RackPack: Premium Mic Pre
9
Control Elements
Mic Gain
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Mic Gain, About Leveling
With the Mic Gain control you can regulate the preamplification of the
microphone signal. It ranges from +12 dB to +80 dB. The input stage can
handle input levels of up to 10 dB. The value set with the Mic Gain control defines the output level equally for both Output 1 and Output 2.
When you set the Mic Gain you have to consider the type of microphone
that you are using (dynamic or condenser microphone) as well as its
sensitivity. The sensitivity of a dynamic microphone is at around 2 mV/
Pa whereas the sensitivity of a condenser microphone can be up to
20 mV/Pa. The result is a difference in output of 20 dB.
You should also consider the sound pressure level of the sound source,
the distance of the microphone to it and the acoustics of the room when
you set the preamplification.
About Leveling
Initially you should always deactivate the -10 dB button to have correct values displayed by the VU meter (see “-10 dB” on page 11). Now
turn up the Mic Gain control until the VU meter displays maximum levels between 0 dB and +3 dB. At this level you don’t risk any overdrive
when you experience sudden and unexpected peaks in the level of the
source. Always remember that the VU meter only shows average values
and that a peak level can be much higher (up to +10 dB). If necessary,
turn on the PPM mode to see the actual peak levels.
Usually levels of around 0 dB and +3 dB are safe. If, however, you experience very high peaks already at minimum Mic Gain values (i.e. drums,
brass instruments), you can activate the PAD function (see “PAD”
on page 12). The input level is now reduced so that you can regulate
Mic Gain again in a useful range.
If you know in advance that the level will be very consistent you can
always turn up Mic Gain. In this case you can activate the -10dB button
to have more headroom in the display.
IMPORTANT: To exclude any audible distortion the OVL LED should
only light up shortly. It starts illuminating 3 dB before a potential overload, so first illumination does not indicate an overload, but that the
limit of leveling is reached. Avoid permanent illumination of the OVL
LED to exclude overloads (also refer to “Overload LED“ on page 13).
10
RackPack: Premium Mic Pre
VU Meter, PPM, -10 dB
Control Elements
VU Meter
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The VU meter displays the output level of the preamp. The gauge indicates levels from -20 dB to +5 dB. If necessary you can lower the sensitivity by 10 dB so that the gauge goes up to +15 dB output level (see
“-10dB” below and “About Leveling” on the previous page).
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An especially interesting feature is the option to switch between two
display modes: VU mode and PPM mode. The VU mode (VU=Volume
Unit) displays average levels, thus provides information on the overall loudness. The PPM mode (PPM=Peak Program Meter) displays the
peak levels.
The integration time of the display complies with the BBC requirements. In VU mode the rise time up to 0 dB is approx. 300 ms. In PPM
mode the rise time up to 0 dB is about 2 ms and the release time down
to -20 dB is at a “slow” 1,5 seconds. This calibration ensures to display
even short peaks up to about +6 dB since the needle does not have to
travel the entire distance of the gauge every time.
11.
The PPM button allows to switch the VU metering characteristics from
VU display mode (button is deactivated and not illuminated) to PPM
display mode (button is active and illuminated). A/D converter display
also make use of the PPM mode. Monitoring peak levels is most important to avoid overloading the converter and to prevent audible distortion. Peak levels are always above the average levels. It may make
sense in most cases to also press the -10 dB button to prevent the needle from getting stuck on the right side of the gauge. -10dB
°
With this button you can change the sensitivity of the VU display. If you
press the -10 dB button (button is illuminated), the sensitivity of the
display is lowered by 10 dB. With the needle for example at 0dB, a value
of +10 dB is displayed. Now you can read values of up to +15 dB.
You always have to add these 10 dB to the displayed values, for example
if you compare these values with those of an A/D converter. Remember
that A/D converters show peak levels, not average levels. For comparison press the PPM button to activate the PPM mode.
RackPack: Premium Mic Pre
11
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OVL
The VU meter is custom made to meet SPL specifications and assures a
balanced optical perception thanks to it’s optimized ballistics.
PPM
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VU
Control Elements
48 V Phantom Power Supply, Pad
48 V Phantom Power Supply
7
The Premium Mic Pre provides 48 volt phantom power for microphones
requiring external current (generally condenser microphones). Such
microphones are dependent upon a clean, consistent and noise-free
power supply for optimal operation and audio quality. The Premium
Mic Pre continuously delivers precisely 48 V and a maximum current of
14 mA, which will power all microphones.
IMPORTANT: All microphones with balanced, ground-free outputs can
be used with the phantom power activated. Unbalanced microphones
may only be used with phantom power deactivated.
Phantom power should only be activated when using microphones that
require it. Please be sure to deactivate phantom power with all other
microphones (including tube microphones which are supplied from
their own power supply, thus need no extra phantom power supply).
ALWAYS FOLLOW THESE RULES WHEN WORKING WITH PHANTOM
POWER – THE INPUT STAGES OF THE PREMIUM MIC PRE CAN BE
DAMAGED IF YOU DO NOT ACT ACCORDINGLY:
1)First connect the microphone to the Premium Mic Pre.
2)Then activate phantom power – you can start working now.
3)When you have finished recording, turn the phantom power off first.
4)DO NOT disconnect the microphone from the Premium Mic Pre UNTIL
phantom power has been switched off for a minute and all residual
current is discharged.
Pad
1"%
The Pad function allows you to attenuate the input signal by 20 dB so
that you can process even very high levels, i.e. from drums or brass
instruments.
If the VU meter shows levels above +3 dB even while Mic Gain is set very
low (and the -10 dB button deactivated), the time has come to press the
Pad button. It illuminates when it is activated.
12
RackPack: Premium Mic Pre
Phase Reverse, High Pass Filter
Control Elements
Phase Reverse

With the phase reverse button you invert the polarity of the microphone signal. When not pressed (button is not illuminated) the polarity
is in phase. After pushing the button (button is illuminated) the polarity is inverted.
The phase reverse feature comes in very handy if you have to switch the
polarity of the XLR input according to the polarity of the microphone or
the microphone cable. The pin wiring of the XLR sockets are as follows:
Pin 1 = ground, Pin 2 = hot (+), Pin 3 = cold (-).
Sometimes it is useful to switch the polarity of a microphone, for example in the case of M/S miking. A second classic application is the miking
of a snare drum with two microphones that are placed above and below
the snare: Since both drum heads move in the same direction when the
drum is played, the microphones are out of phase. Switch the polarity
of the bottom mic and you avoid any cancellations when you join both
signals in the mix.
High-Pass Filter
The high-pass filter, also known as rumble filter, helps to eliminate any
interferences within the lowest frequencies. The first order filter operates smoothly with 6 dB per octave, starting from 75 Hz with -3 dB.
This characteristic usually helps in most cases and has the least sonic
disadvantages. If you need to filter on a more extreme scale, even
second order filters (12 dB/octave) are overstrained frequently and
sonic disadvantages become more and more apparent. In those cases
a variable filter is the means of choice.
Signal LED
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The signal LED (SIG) indicates immediately whether an input signal
is existent or not. The LED starts responding at a minimum level of
-25 dB.
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Overload LED
The overload LED (OVL) warns 3 dB before a potential internal overload, thus indicates that a headroom of 3 dB is left. Avoid overloads
as they may result in unwanted distortions. As soon as the OVL LED
illuminates permanently you have to reduce the amplification with the
Mic Gain control until the LED turns off or only lights up shortly (also
refer to “About Leveling” on page 10).
RackPack: Premium Mic Pre
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Technology
Triple Stage Preamp, Stage 1 – The Input Transformer
Triple Stage Preamp
The preamplifier circuitry of the Premium Mic Pre is composed of three
stages: a transformer, a discrete differential amplifier stage and an instrument preamplifier all contribute (in different shares) to the main
amplification. The three stage setup firstly ensures a load distribution
that minimizes the risk of overloads. Secondly, each stage can be optimally configured through select components and sophisticated circuits – a decisive advantage over single IC circuitries where the main
amplification is achieved by just one stage.
In addition, the potentiometer (as the control element of the differential
amplifier stage) only has to cover a range of approximately 68 dB while
the maximum amplification is at around 80 dB. In practice this means
that even very high amplification values are still outside of the extreme
control range positions – which are critical for any potentiometer.
Stage 1 – The Input Transformer
Inherent part of the Premium Mic Pre design are the input and output
transformers of the High Performance Series by Lundahl. These transformers are lavishly handcrafted. They replace common input and
output balancing stages. These classic components offer a very high
sound quality and common mode rejection but they are also very reliable and provide connections and signals of superior quality.
Lundahl transformers have a very high reputation in terms of manufacturing quality and the resulting longevity as we have seen proven
impressively throughout many years of experience.
In any microphone preamplifier the input transformer is of special relevance as it is an integral part of the preamp circuitry: it contributes
to the main amplification through a passive and permanent boost of,
in this case, 6 dB. The advantage of passive amplification over active
amplification is that it does not add any noise. A second advantage of
integrating this passive amplification is a signal processing that is, as a
matter of principle, lower in overdrive and noise throughout all following stages simply because the rest of the electronic circuit is charged
with 6 dB less at any setting of the amplification.
In addition, transformers ensure a galvanic isolation, preventing any
disturbing or damaging voltages from being carried in any of the two
directions. Electromagnetic, high frequency or digital interference has
no more influence. Problems with humming e. g. in a live environment
that have been caused by differences in the potentials between the
stage and the FOH do not occur. >
14
RackPack: Premium Mic Pre
Stage 2 – The Discrete Differential Amplifier
Technology
Even a voltage that has accidentally or through technical failure been
connected to a ground line cannot be transmitted. So transformers can
exclude even mishaps or problems in an installation reaching the categories “improbable” till “unbelievable” ...
Further, the phantom powering of microphones does not require any
condensers in the preamp socket which has further sonic advantages.
From our personal listening impression we can recommend transformers in any case. The advantages in operational safety can not be overestimated especially in critical or complex installations for studio, live
or broadcast applications.
Stage 2 – The Discrete Differential Amplifier
From the input transformer, the signal is routed to a discrete differential amplifier based upon a quad parallel transistor circuitry. This parallel circuit of eight single transistors reduces noise remarkably through
distribution of load.
The discrete differential amplifier is the central amplifying stage; here
the amount of the amplification is controlled by a current-carrying
source. Control systems that are triggered by current rather than voltage have the main advantage that possible negative effects of the potentiometer will not affect the audio signal.
The discrete differential amplifier offers a maximum amplification of
up to 68 dB. A servo drive circuit actively eliminates DC offsets of the
differential amplifier. Servo drive circuitry minimizes DC offsets more
effectively than conventional solutions that utilize capacitors by setting the DC offset to almost 0 mV. In addition, the active servo drive
solution has sonic advantages over passive capacitors as it tends to
produce less distortions.
RackPack: Premium Mic Pre
15
Technology
Stage 3, Capacitors, Output Stages, Channel Split
Stage 3 – The Instrumentation Amplifier
An instrumentation amplifier is following the discrete differential amplifier to produce the output signal’s voltage. Functionally a summing
amplifier it eliminates possible disturbing voltages and also contributes to the main amplification with an additional +6 dB.
Foil and Styroflex Capacitors
Only the best MKP and styroflex capacitors are used in the various circuits. They sound more open and dynamic in contrast to the conventional ceramic capacitors.
Output Stages
The Premium Mic Pre offers two balanced output stages: a transformer
output (Output 1) and an electronically balanced stage (Output 2).
These output stages are capable of driving very long cables (up to a
few hundred yards, depending on the capacity of the cables and the
input stages on the other end). The maximum output level is +22 dBu.
Channel Split
Since the Premium Mic Pre provides two independent outputs, it always offers you two routes for one input channel.
If, for example, a RackPack is configured as a channel strip, one preamp output can feed the next module while the second output is used
to record the direct preamp signal.
Another exemplary studio application is to send one signal directly into
the A/D converter to be recorded in your DAW while the second signal
is used for latency-free monitoring (e.g. cue mix for the singer).
When playing live output 1 can be routed to the Front Of House (FOH)
while output 2 feeds the monitoring mixer.
16
RackPack: Premium Mic Pre
Copy Master: Recall Settings
Artist:
...........................................
%
7 5
10
20
30
0
50
3
1 0
70
100
100
3
5
VU
SIG
OVL
Album:
...........................................
7
11.
76

Title:
°
...........................................
1"%
.*$("*/
...........................................
&.
Engineer:
13
* 6 . E#
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.*$13
Track(s)/Group:
...........................................
Date:
...........................................
RackPack: Premium Mic Pre
17
Specifications
Audio
Frequency Range
10 Hz- 68 kHz (-3 dB)
CMRR
-87 dBu
(at 1kHz with -30 dBu input level and 30 dB Gain)
THD & N @ 1 kHz
Input Level
-30 dBu
-60 dBu
Gain
30 dB
60 dB
THD & N
0,0071%
0,078%
Noise
Gain
80 dB
60 dB
30 dB
Noise Level (A-wtd.)
-48,3 dBu
-64,2 dBu
-89,0 dBu
E.I.N. (Equivalent Input Noise) -128,3 dBu
Dynamic Range
111,0 dB
Input
XLR connector, transformer balanced
Impedance unbalanced
ca. 2,0 kOhm
Impedance balanced ca. 4,0 kOhm
max. Input Level
+10 dBu, +30 dBu with Pad activated
Outputs
Output 1: XLR connector, transformer balanced
Impedance unbalanced
ca. 60 Ohm
Impedance balanced ca. 120 Ohm
Max. Output Level
+22 dBu
Output 2: XLR connector, electronically balanced
Impedance unbalanced
ca. 75 Ohm
Impedance balanced
ca. 150 Ohm
Max. Output Level
+22 dBu
Control Elements
Mic Gain Range
Pad
High-Pass Phantom Power Supply
12 dB – 80 dB
-20 dB
fg = 75 Hz (-3dB)
48 V
Dimensions & Weight
Height x Width x Depth
Weight
132 mm x 46,9 mm x 315 mm
0,55 kg
Note: 0 dBu = 0.775 V. Specifications are subject to change without notice.
18
RackPack: Premium Mic Pre
Measurements
Sound Performance Lab
CMRR
08/20/07 12:03:48
-50
-60
d
B
u
-70
-80
-90
-100
10
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
CMRR with -30dBu input level and vu = 30dB
black = input -> output 1
grey = input -> output 2
CMRR -30dB.at27
Sound Performance Lab
Frequency Response / THD+N
ratio
08/20/07 12:04:29
+3
0.2
0.175
+2
0.15
+1
d
B
u
0.125
+0
0.1
0.075
-1
0.05
-2
0.025
-3
10
20
50
100
200
500
1k
2k
5k
10k
20k
100k
Hz
Frequency Response and THD + N ratio with -30dBu input level and vu = 30dB
black = frequency response
grey = THD + N ratio
Freq Resp + THD.at27
RackPack: Premium Mic Pre
19
%
Block Diagram
20
RackPack: Premium Mic Pre
Guarantee
Guarantee, Product Registration
All SPL products come with a two-year manufacturer’s guarantee
against defects in material or assembly from the date of purchase. End
users are supported in the two-year guarantee through their distributor or dealer. In such cases, please contact your dealer for full guarantee conditions and service.
Direct SPL product support requires product registration. Please fill
out the guarantee card enclosed in the package legibly in printed letters and send it directly to SPL. Or use the online registration form that
may be reached at www.soundperformancelab.com (international clients) or www.spl-usa.com (US clients).
RackPack: Premium Mic Pre
21
<Manual Premium Mic Pre
Model 2712
RackPack: Premium Mic Pre