TUBE EQ
PROFESSIONAL TUBE PARAMETRIC EQUALIZER
USER’S GUIDE
Table of Contents
Introduction
Features
Registration
Overview
EQ Tips
Unpacking
AC Power Hookup
Audio Connections
Installation
Safety Precautions
Powering Up
Front Panel Controls and Indicators
Bypass Switch
Gain Control
Clip Indicator
Output Level Control
Instruments and the Audio Spectrum
Low Frequency Control
Low Shift Switch
Lo-Mid Frequency Control
Low-Mid Shift x10 Switch
Hi-Mid Frequency Control
Hi-Mid Shift x10 Switch
High Frequency Control
High Shift Switch
Rear Panel Connections
Power Switch
Input
Output
Tube Replacement
Applications
Specifications
On-line Information
Warranty Information
Service Information
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128-5004-101
Introduction
Thank you for purchasing Applied Research and Technology’s
Tube EQ. The Tube EQ may be used anywhere you need equalization or frequency adjustments. Offering a superb level of
sound quality, the Tube EQ will enhance the sonic textures of
your audio system for years to come.
Features
The Tube EQ is a unique product. While every EQ gives you the
ability to alter the frequency characteristics of a signal, very few
sound really good when doing so. Developed in partnership with
studio and live sound engineers, the Tube EQ possesses flexibility
and “sound” that is not available from any other product on the
market - at any price! The Tube EQ was designed and constructed with the best components, assuring a lifetime of quiet, reliable performance. The Tube EQ offers:
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The award-winning A R T “SOUND”!
Tube-based four-band equalization
Selectable Low shelving filter - 40Hz or 120Hz
Selectable High shelving filter - 6KHz or 18KHz
Sweepable Lo and Hi mid-frequency bands
Mid-frequency bands overlap from 200Hz to 2KHz
Mid-frequency bands sweepable from 20Hz to 20KHz
Hand-selected 12AX7a tube
XLR balanced inputs and outputs
1/4” TS unbalanced inputs and outputs
Custom extruded aluminum chassis
Independent input and output level controls
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Detented rotary controls
>90dB dynamic range
Internal power supply
One year warranty
Designed and manufactured in the USA
Registration
If you haven’t done so already, please take the time to fill out the
User Registration Card for your purchase. Having you in our
database allows us to keep you informed of updates, application
notes, and new product introductions. It only takes a moment,
and it will ensure that you are constantly up to date with your
purchase.
Fill in the following for your future reference:
Date of purchase: ___________________
Purchased From: ____________________
Serial Number: 128-________
Overview
Great recordings and great mixes are made from great sounds.
With the exception of some classical and environmental recordings, equalization plays a large role in creating, tweaking and
capturing great sounds in contemporary music. A good equalizer
will make good sounds sound better, and (more importantly) bad
sounds sound better.
Since we don’t live in a perfect world where all instruments and
sounds are “record-ready”, A R T created the Tube EQ to make
our recordings a little easier and (hopefully) a little better.
The Tube EQ was designed to help “fix” the instruments that give
us the most headaches when we’re recording: kick, snare, bass,
toms, guitar amps, voice, etc. The two sweepable parametric
bands and selectable shelving bands have been optimized for
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musical instruments. The two sweepable bands overlap themselves and the high and low shelving bands, providing you with
the ultimate in flexibility. The Tube EQ gives you all the control
you need to effectively alter and dial in great sounds from even
the poorest of sources.
EQ Tips
Why use an external EQ?
The shortest signal path is the best way to get a signal to tape.
In most cases, the shortest path is: mic to preamp to compressor
to EQ to tape deck. The signal doesn’t even go through the
mixer! This isn’t a new concept, but it has become more relevant
with the availability of affordable mixing consoles. As their name
implies, most affordable mixers excel in signal routing and mixing capabilities. However, they are not necessarily your best
option for recording tracks. While their onboard EQ is nearly
always adequate for tweaking a good recorded track during
mixing, the simple truth is that the Tube EQ is a better sounding
and more flexible equalizer. Mixer manufacturers need to make
trade-offs to keep prices down while keeping performance up.
Imagine the price of your mixer if each channels’ EQ cost over
$200 (and we’re not talking about those of you who have one of
those $250,000+ consoles!)
The use of external processing (equalizers, preamps and compressors) has sonic and practical benefits when you consider that
most recording is done one or two channels at a time. For those
of us on a budget, it just doesn’t make sense to spend a ton of
money on a “cadillac” console when a budget mixer and a few
pieces of external gear is more cost effective. Even those engineers who regularly work on “big” consoles use external EQs
and preamps!
The goal of any recording is to get the sounds right before you
commit them to tape. The Tube EQ exists to help you get it right
so you don’t have to “fix it in the mix”.
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Why should I use a parametric EQ instead of a graphic EQ?
Every EQ has its place. As a general rule of thumb, parametric
EQs are used for individual instruments (or tracks) and graphic
EQs are used for mixed material and for playback systems.
Parametric EQs give you more control over a signal -- they can
provide subtle or drastic results because they can be tuned to
specific frequencies. Parametric EQs allow you to boost or cut
narrow frequency bands to make individual instruments “sit” better with other instruments when combined in a mix. This is usually accomplished with one or two bands. Graphic EQs are used
more for the shaping of material. They are nearly always used in
PA systems because they can adjust the speaker system to fit the
needs of a room while still sounding natural. Their application is
“broader” than that of a parametric.
What is the best way to use EQ?
There are two schools of thought on EQ: 1) Use as much as you
need to make things sound good. 2) Don’t use any EQ. Most
people follow the suggestion of “if it sounds good, it is good.”
You need to use your ears and judge for yourself as their are no
steadfast rules for EQ’ing. Here are a few pointers to guide you.
Always tweak the instrument you are EQ’ing while listening to it
in the mix. EQ’ing an instrument when it is soloed doesn’t give
you a good representation of how it will sound when mixed with
other instruments. You’d be surprised at how bad a killer guitar
track can sound when it is isolated from the rest of the mix.
Remember, what makes it killer is how it sounds in relation to
the other instruments! Keep the big picture in mind.
Most people think of EQ as boosting only (“we’ll just add a little
EQ...”). Many times a “bad” sounding instrument can be fixed
by simply isolating the bad frequency and pulling it out. After
you determine approximately where the “problem area” is in the
instrument (highs, lows, mids), isolate the track and boost one of
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the mid bands. Slowly sweep through the frequency range.
When the really nasty sound jumps out at you (you’ll know it
when it happens) turn the boost back to “0” (12 o’clock). Now
put the track back into the mix and cut the frequency. You’ll have
to adjust the level of the instrument depending on how much you
cut, but you should find that with the “problem area” pulled out,
the instrument works better in the mix.
When recording EQ’d instruments you want to make sure you
have good representation of frequencies on tape. Always monitor “off” tape when recording. This ensures that what you’re
hearing is what is on tape. When recording things like kick
drums, make sure you have enough low end “thud” and high
end “click” (if applicable) before you record.
Recording guideline: You can always boost or cut frequencies
after they’ve been recorded, but you can’t add frequencies that
weren’t’ recorded! Always be prepared for the drummer who
says he loves the John Bonham kick drum sound (lots of low end
power and ambience) you got when recording but during the
mix decides he wants to sound like Metallica (more click than
punch).
If you get the sounds right when you record the tracks you
shouldn’t be spending a lot of time re-EQ’ing during the mix.
During mixing you should be concentrating on the blending of
tracks and the dynamics of the song. If you find yourself EQ’ing
everything, take a break and come back to it later. Start mixing
with a group of instruments (the whole drum kit or guitars and
bass) instead of listening to individual tracks. Mixing is the time
for tweaking - not applying a sonic re-design.
Once again, “if it sounds good, print it!” Trust your ears - nevermind where the knobs are pointing.
Unpacking
Your Tube EQ was packed with care at the factory. The shipping
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carton was designed to protect it during initial shipment. Please
retain this carton for use in transporting the Tube EQ, or in the
unlikely event that you need to return your Tube EQ for servicing.
AC Power Hookup
The Tube EQ has an internal power supply designed to operate
at 100 to 125VAC, 50 to 60Hz. Units manufactured for use outside of the United States of America have been modified to comply with the required electrical specifications. Under no circumstances should the power cable be altered. If the cable becomes
cut or damaged, discontinue its use and have it replaced before
using the Tube EQ.
Audio Connections
Audio connections to and from the Tube EQ are balanced XLR
(Pin 2 Hot (+), Pin 3 Cold (-), Pin 1 Ground) and unbalanced
1/4” (Tip Hot (+), Sleeve Ground). We recommend using only
high-quality cables equipped with the appropriate connectors.
Installation
The Tube EQ may be employed in a number of setups
including:
- Between a microphone/ line preamplifier and a mixer, digital
multi-track recorder, DAT machine, hard disk recorder, or analog
recorder.
- In a mixer’s channel insert points.
- Between a microphone/ line preamplifier and signal processors.
- Between electronic musical instruments (synthesizers, guitars,
bass, samplers, acoustic instruments with pickups) and
other gear.
SAFETY PRECAUTIONS
Warning: To avoid the risk of shock or fire, do not expose this
unit to moisture. Do not remove metal panels from chassis parts.
Removing the chassis from its cabinet parts exposes dangerous
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voltages. There are no user-serviceable parts inside. Refer all
servicing to qualified personnel. Note: If your power cord
becomes damaged and must be replaced, always replace it with
the proper type (3 prong).
POWERING UP
When the rear panel power switch is turned on, the power indicator LED will illuminate. It is important to remember to turn the
Tube EQ on before any monitoring levels or power amps are
turned on. The Tube EQ has the ability to add gain to its input
signal. This can cause the Tube EQ to produce a “thump” on
power up and power down.
Note: Like all tube-based equipment, the Tube EQ needs to
warm up before being used. Allow one to two minutes for the
tubes to reach proper operating temperature before using.
It is normal for the Tube EQ to be warm. The aluminum chassis
is used for heat dissipation. It is recommended that the Tube EQ
be installed in an area where there is adequate ventilation.
If the Tube EQ fails to power up when the power switch is turned
on, check to see that its power cord is plugged into an active
outlet. If the unit still fails to operate properly, turn it off and
unplug it. Then consult your dealer or A R T’s Customer Service
department.
FRONT PANEL CONTROLS & INDICATORS
Bypass Switch
A Bypass switch is included on the Tube EQ to enable you to
remove it from your signal chain. When set to its “in” (bypass)
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position, signal is allowed to pass from the input to the output
with no equalization. The green power LED will glow red when
Bypass is engaged. In its “out” position, the EQ is active. Use the
Bypass switch when setting the Tube EQ’s input and output levels
to achieve unity (no boost or cut) gain. Unity gain is achieved
when the active level is the same as the bypassed level.
Gain Control
The Gain control sets the amount of input gain to the Tube EQ.
Turn the control clockwise to increase gain and counterclockwise
to decrease it. To maximize your signal to noise ratio, it is important to start with a unity gain setting (meaning that the level into
the Tube EQ is the same as the level out of the Tube EQ). With
the output level at its “0” position, adjust the input gain until the
level is the same when the Tube EQ is bypassed and active.
Clip Indicator
The Clip indicator will illuminate just before any gain stage of
the Tube EQ reaches audible distortion. Typically this will indicate
clipping at the input stage (which is corrected by turning down
the input gain control). However, it will also indicate any distortion caused by excessive EQ’ing. In other words, if turning down
the input gain control doesn’t make the clip indicator turn off,
check the frequency bands for excessive boost.
Output Level Control
The Output Level control sets the output level of the Tube EQ.
The output level is a gain stage intended to compensate for a
boost or cut in level from the applied EQ. When the control is
fully counterclockwise, there is no output. Turning the control
clockwise increases the level of the output to a maximum of
+10dB of gain. To achieve unity gain (meaning the level into the
Tube EQ is the same as the level out of the Tube EQ) the output
level should be adjusted after setting the EQ bands so that the
bypass level is the same as the active level. If you are boosting
EQ bands (adding gain), you’ll have to turn down the output
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level control. If you are cutting EQ bands (decreasing gain),
you’ll have to turn up the output level control.
Note: Using the Tube EQ for adding gain will not damage the
unit. The only thing that will suffer will be the signal to noise
ratio (meaning that if you use the Tube EQ as a distortion box, it
will probably be noisy). However, use caution and observe the
input levels of the equipment that the Tube EQ is plugged into to
be sure you are not overdriving it.
Instruments and the Audio Spectrum
The following chart gives you an idea of where certain instruments lie in the audio spectrum. If an instrument isn’t listed, use
the one which most closely resembles it. The descriptions in quotations are references for you to experiment with. For example, if
you have a kick drum with no “click” from the beater, try boosting around 2 - 2.5KHz. Since every instrument, microphone and
room is different, these are only approximations but should give
you a good place to start.
Low Frequency Control
The Low Frequency control adjusts a shelving filter with a selectable corner frequency of either 40Hz or 120Hz. The low shelving filter designed into the Tube EQ affects all frequencies below
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the corner frequency when applying boost or cut. In other words,
cutting at 40Hz also cuts 30Hz, 20Hz, etc. The Low Frequency
control has as range of +/- 12dB. Two ranges are selected with
the Low Shift Switch: 40Hz or 120Hz. 40Hz is great for enhancing sub-low frequencies such as those in bass guitars and kick
drums. Cutting 40Hz can also help to “clean up” mixes that
sound muddy or “loose” in the low end. 120Hz is generally the
low-end for vocals, guitars and toms. Boosting 120Hz can add
“weight” or “beef” to a week vocal and cutting it can “thin out”
a signal that takes up too much room in the low end.
Low Shift Switch
The Low Shift switch selects the corner frequency of the Low
Frequency control. In the “out” position the corner is 40Hz. In
the “in” position the corner is 120Hz.
Lo-Mid Frequency Control
The Lo-Mid control is a dual concentric pot (meaning there are
two controls - one outer and one inner). The outer control is
used to select a frequency while the inner control is used to
apply +/-12dB of gain. The Lo-Mid control can cover two frequency ranges depending on the position of the Shift x 10
switch. These ranges are 20Hz to 200Hz and 200Hz to 2KHz.
Lo-Mid Shift x 10 Switch
The Lo-Mid Shift x 10 switch determines the range over which
the Lo-Mid frequency control will cover. In its “out” position, the
range is set at 20Hz to 200Hz. In its “in” position the range is
set at 200Hz to 2KHz.
Note: You’ll notice the Low Frequency and Lo-Mid Frequency
controls overlap (meaning they cover the same frequencies). This
is intentional and is one of the powerful features of the Tube EQ.
This feature allows you the ultimate in flexibility.
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Hi-Mid Frequency Control
The Hi-Mid control is a dual concentric pot (meaning there are
two controls - one outer and one inner). The outer control is
used to select a frequency while the inner control is used to
apply +/-12dB of gain. The Hi-Mid control can cover two frequency ranges depending on the position of the Shift x 10
switch. These ranges are 200Hz to 2KHz and 2KHz to 20KHz.
Hi-Mid Shift x 10 Switch
The Hi-Mid Shift x 10 switch determines the range over which the
Hi-Mid Frequency control will cover. In its “out” position the
range is set at 200Hz to 2KHz. In its “in” position the range is
set at 2KHz to 20KHz.
Note: You’ll notice the Lo-Mid and Hi-Mid Frequency controls
overlap (meaning they cover the same frequencies) in the 200Hz
to 2KHz range. This is intentional and is another of the powerful
features of the Tube EQ. This feature allows either or both controls to be used in this range. This is extremely useful if you want
to cut at 200Hz and boost at 350Hz.
High Frequency Control
The High Frequency control adjusts a shelving filter with a selectable corner frequency of either 6KHz or 18KHz. The high shelving filter designed into the Tube EQ affects all frequencies above
the corner frequency when applying boost or cut. In other words,
cutting at 6KHz also cuts 7KHz, 8KHz, etc. The High Frequency
control has as range of +/- 12dB. The two ranges are selected
with the High Shift switch. 6KHz is great for adding top end to
guitars, snare drums and vocals. Cutting 6KHz can also help to
“take the edge off” brittle or harsh sounding instruments. 18KHz
may be used to add “sizzle” to cymbals and is generally referred
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to as the “air” band. While there aren’t very many instruments
that contain 18KHz information directly, many instruments and
mixes contain upper harmonics which can add extra definition
and “space” when boosted. Cutting at 18KHz can decrease hiss
and noise.
High Shift Switch
The High Shift switch selects the corner frequency of the High
Frequency control. In the “out” position the corner is 18KHz. In
the “in” position the corner is 6KHz.
Note: You’ll notice the High Frequency and Hi-Mid Frequency
controls overlap (meaning they cover the same frequencies). This
is intentional and is one of the powerful features of the Tube EQ.
This feature allows you the ultimate in flexibility. For example, on
cymbals try boosting 18KHz with the High control while cutting
20KHz with the Hi-Mid control for a very bright, yet noise free
result.
REAR PANEL CONNECTIONS
Power
The Power switch applies and removes power from the unit. The
Tube EQ should be turned “on” only when all monitor levels are
turned down, or off, to protect against any “thumping” caused
by high gain settings. Likewise, the Tube EQ should be turned
“off” after turning all monitor levels down.
Input and Output Connections
The Tube EQ’s XLR connectors follow the AES standard:
Pin 1 = Ground, Pin 2 = Hot (+), Pin 3 = Cold (-). The unbalanced 1/4” phone jacks are typical: Tip = Hot (+), Sleeve =
Grd.
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Input
One input jack per channel should be used at a time. Because
of its design, the Tube EQ can be hard-wired without having to
disconnect the XLR inputs when using the 1/4” jacks. In this case,
if no load is placed on the XLR input (no instrument or line-level
source connected) the 1/4” jack will function as if there was
nothing connected to the XLR input. However, the inverse is NOT
true. If you are using the XLR input, you should not have anything plugged into the 1/4” jack.
Output
Both balanced and unbalanced output connections may be used
simultaneously. However, when using the Tube EQ to convert an
unbalanced signal to a balanced signal (and vise-versa) you will
experience a level difference between the input and output signals. This isn’t a big deal as you can compensate with the Input
and Output Level controls, but the front panel “0” indicators will
not be accurate unless using common connectors (both XLRs or
both 1/4).
Note: If you experience a hum when using both output connectors simultaneously (one to the console and one to an instrument
amp), a ground loop may be the problem. To remedy this problem, disconnect the ground wire (pin 1) from the XLR cable
plugged into the Tube EQ’s output (or use a ground-lifted audio
cable). This interrupts the ground path and therefore breaks the
loop.
Tube Replacement
The tube in your Tube EQ should last for many years. The tubes
used in your unit are hand-sorted for performance. In the event
that you need to replace them, A R T suggests that you do so
with tubes available from A R T. These are matched to the Tube
EQ and will yield consistent sonic results. You’ll find these tubes
to be very reasonably priced. You can replace the tubes with
other brands, however A R T has no responsibility for the result-
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ing sound quality. They may sound better, they may sound
worse. The choice is yours. Please realize that unauthorized
alterations to the Tube EQ will void the warranty.
APPLICATIONS
The Tube EQ is intended for use with line level sources. The
proper placement of the Tube EQ in a signal chain is: after a
mic/line preamplifier, after a direct output or bus output from a
console, after the output of a tape deck, or in the insert point of
a mixer.
The Tube EQ has gain and it is possible to plug an instrument
directly into it. However, the Tube EQ does not have enough
gain to plug a microphone into it.
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A R T Tube EQ Specifications
Dimensions:
Weight:
Frequency Bands:
Low Shelf:
Low-Mid Sweepable:
High-Mid Sweepable:
High Shelf:
Gain/Frequency Band:
Dynamic Range:
Input Impedance:
Output Impedance:
Maximum Input Level:
Maximum Output Level:
Total Harmonic Distortion (THD):
Tube:
Power Requirements:
5.25"D x 8.5"W x 1.65"H
5.0 lbs
40Hz/120Hz Selectable
20Hz to 200Hz/ 200Hz to 2KHz
200Hz to 2KHz/ 2KHz to 20KHz
6KHz/18KHz Selectable
+/- 12dB
>90dB (no weighting)
20k ohms (XLR), 1M Ohm (1/4”)
600 ohms (XLR), 300 Ohms (1/4”)
+20dBu (XLR)
+27dBu (XLR), +22dBu (1/4”)
<0.1%
Hand Selected 12AX7a
100-125 VAC, 9W Export units
configured for country of destination
A R T retains a policy of constant product improvement. A R T reserves the right
to make changes in design or make additions to or improvements upon this
product without any obligation to install the same on products previously manufactured. In other words, specifications are subject to change without notice.
Designed and manufactured in the United States of America.
Applied Research and Technology, Inc.
215 Tremont Street
Rochester, NY 14608 USA
(716) 436-2720 (Phone)
(716) 436-3942 (FAX)
WE’RE ON-LINE!
For Product information, questions, applications, tips, answers and general discussion with A R T employees look for A R T on the Internet..
Check out our Web Page at: http://www.artroch.com
Look for the A R T discussion area in Craig Anderton’s Stage Studio and Sound
(http://www. 3daudioinc.com) under the Manufacturer Supported Forums. Email
us at artroch@aol.com
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Look for the A R T supported area in the MIDI Forum B area on CompuServe
(Go MIDI). CompuServe address: 76702,3700. Email us at artroch@cis.compuserve.com
WARRANTY AND SERVICE INFORMATION
Limited Warranty
Warranty service for this unit will be provided by Applied
Research and Technology, Inc. in accordance with the following
warranty statement.
Applied Research and Technology, Inc. (A R T) warrants to the
original purchaser that this product is free from defects in workmanship and materials for a period of one year from the date of
purchase. A R T will, without charge, repair or replace, at its
option, defective product or component parts upon prepaid
delivery to the factory service department or an authorized service center, accompanied by proof of purchase date in the form
of a valid sales receipt.
EXCLUSIONS: This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs. This warranty is void if the serial number is
altered, defaced or removed.
A R T reserves the right to make changes in design and make
additions or improvements upon this product without any obligation to install the same on products previously manufactured.
A R T should not be liable for any consequential damages,
including without limitation damages resulting from the loss of
use. Some states do not allow limitation of incidental or consequential damages, so the above limitation or exclusion may not
apply to you. This warranty gives you specific rights and you may
also have other rights which vary from state to state.
For products purchased outside the United States, service will be
provided by an authorized distributor of Applied Research and
Technology, Inc. products.
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SERVICE
The following information is provided in the unlikely event that
your unit requires service. Use this procedure to return units in
the United States only. For service outside the United States,
please contact your authorized A R T distributor.
1) Be sure the unit is the cause of the problem. Check to make
sure the unit has power supplied, all cables are connected correctly, and the cables themselves are in working condition.
2) If you find the unit to be at fault, write down a description of
the problem, including how and when the problem occurs.
3) Call the factory for a Return Authorization (RA) number.
4) Pack the unit in its original carton or reasonable substitute.
The packing box is not recommended for a shipping carton. Put
the packaged unit in another box for shipping. Print the RA number clearly under the address.
5) Include with your unit: a return shipping address (we cannot
ship to a P.O. Box), a copy of your purchase receipt, a daytime
phone number and the description of the problem.
6) Ship the unit to:
Applied Research and Technology, Inc.
215 Tremont Street
Rochester, NY 14608
Atten: Repair Department
R.A.# _______________
7) Contact our Customer Service department at (716) 436-2720
for your Return Authorization number or questions regarding
your repair. Customer Service hours are Monday through Friday
9:00AM to 5:00PM Eastern time.
©1998 Applied Research and Technology, Inc.
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