Tapco Tweeq T-231 User manual

LEVEL
LEVEL
1
2
+17
0
-12
+12
+12
-12
+17
00
CLIP
RANGE
6dB 12dB
HI-PASS LOW -PASS
40Hz 16kHz
CLIP 6dB 12dB40Hz 16kHz
BYPASS
RANGEHI-PASS LOW -PASS BYPASS
POWER
ON
OFF
DUAL 31-BAND GRAPHIC EQUALIZER
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 800250 630 1.6k 4k3.15k 8k 16k 20k
BY T•231
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 8 00250 630 1.6k 4k3.15k 8k 16k 20k
2
1
2
WARNING : TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS EQUIPMENTTO RAIN OR MOISTURE. DO NOT REMOVE COVER.
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.
AVIS : RISQUEDE CHOC ELECTRIQUE — NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
UNBAL BALBAL/UNBAL
BAL/UNBAL
BAL
OUT IN
GND
LIFT
315mA 250V
T
SERIAL /DATE CODE OUT IN
OUT IN
OUT IN
UNBAL BAL BAL
OUT IN
OUT IN
CHANNEL 1
CHANNEL 2
RISK OF FIRE
REPLACE FUSE AS MARKED WARNI NG
NO OUTDOOR USE
BROUGHT TO YOUBYTHEGROOVY FOLKSINWOODINVILLE,WA,USA
MANUFACTURED INCHINA
•
FABRIQUEAU CHINE
"TAPCO"AND"MACKIE"ARE REGISTEREDTRADEMARKSOF
LOUD TECHNOLOGIESI
NC. •COPYRIGHT ©2003
WWW.TAPCOGEAR.COM
AC100-120V, 60Hz
AC2
00-240V, 50HZ
RATED INPUT: 12.5W
by

2
SAFETY INSTRUCTIONS
1. Read Instructions — All the safety and operation instructions
should be read before this product is operated.
2. Retain Instructions — The safety and operating instructions
should be kept for future reference.
3. Heed Warnings — All warnings on this product and in these
operating instructions should be followed.
4. Follow Instructions — All operating and other instructions
should be followed.
5. Water and Moisture — This product should not be used near
water – for example, near a bathtub, washbowl, kitchen sink,
laundry tub, in a wet basement, near a swimming pool, etc.
6. Cleaning — Clean only with a dry cloth.
7. Ventilation — This product should be situated so that its location
or position does not interfere with its proper ventilation. For
example, the Component should not be situated on a bed,
sofa, rug, or similar surface that may block any ventilation
openings, or placed in a built-in installation such as a bookcase
or cabinet that may impede the flow of air through ventilation
openings.
8. Heat — This product should be situated away from heat
sources such as radiators, or other devices which produce
heat.
9. Power Sources — This product should be connected to a
power supply only of the type described in these operation
instructions or as marked on this product.
10. Power Cord Protection — Power supply cords should be routed
so that they are not likely to be walked upon or pinched
by items placed upon or against them, paying particular
attention to cords at plugs, convenience receptacles, and
the point where they exit this product.
11. Object and Liquid Entry — Care should be taken so that
objects do not fall on, and liquids are not spilled into, this
product.
12. Damage Requiring Service — This product should be serviced
only by qualified service personnel when:
A. The power-supply cord or the plug has been damaged; or
B. Objects have fallen, or liquid has spilled into this product; or
C.This product has been exposed to rain; or
D. This product does not appear to operate normally or
exhibits a marked change in performance; or
E. This product has been dropped, or its chassis damaged.
13. Servicing — The user should not attempt to service this
product beyond those means described in this operating
manual. All other servicing should be referred to the Tapco
Service Department.
14. To prevent electric shock, do not use this polarized plug with
an extension cord, receptacle or other outlet unless the
blades can be fully inserted to prevent blade exposure.
Pour préevenir les chocs électriques ne pas utiliser cette fiche polariseé avec
un prolongateur, un prise de courant ou une autre sortie de courant, sauf si les
lames peuvent être insérées à fond sans laisser aucune pariie à découvert.
15. Grounding or Polarization — Precautions should be taken so
that the grounding or polarization means of this product is not
defeated.
16. Power Precaution — Unplug this product during lightning
storms or when unused for long periods of time.
17. This apparatus does not exceed the Class A/Class B
(whichever is applicable) limits for radio noise emissions
from digital apparatus as set out in the radio interference
regulations of the Canadian Department of Communications.
ATTENTION —Le présent appareil numérique n’émet pas de bruits radioélectriques
dépassant las limites applicables aux appareils numériques de class A/de class B
(selon le cas) prescrites dans le règlement sur le brouillage radioélectrique édicté
par les ministere des communications du Canada.
WARNING — To reduce
the risk of fire or electric
shock, do not expose
this appliance to rain or
moisture.
PORTABLE CART WARNING
Carts and stands - The
Component should be used
only with a cart or stand
that is recommended by
the manufacturer.
A Component and cart
combination should be
moved with care. Quick
stops, excessive force, and
uneven surfaces may cause
the Component and cart
combination to overturn.
CAUTION AVIS
RISK OF ELECTRIC SHOCK
DO NOT OPEN
RISQUE DE CHOC ELECTRIQUE
NE PAS OUVRIR
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK
DO NOT REMOVE COVER (OR BACK)
NO USER-SERVICEABLE PARTS INSIDE
REFER SERVICING TO QUALIFIED PERSONNEL
ATTENTION: POUR EVITER LES RISQUES DE CHOC
ELECTRIQUE, NE PAS ENLEVER LE COUVERCLE. AUCUN
ENTRETIEN DE PIECES INTERIEURES PAR L'USAGER. CONFIER
L'ENTRETIEN AU PERSONNEL QUALIFIE.
AVIS: POUR EVITER LES RISQUES D'INCENDIE OU
D'ELECTROCUTION, N'EXPOSEZ PAS CET ARTICLE
A LA PLUIE OU A L'HUMIDITE
The lightning flash with arrowhead symbol within an equilateral
triangle is intended to alert the user to the presence of uninsulated
“dangerous voltage”within the product’s enclosure that may be
of sufficient magnitude to constitute a risk of electric shock to persons.
Le symbole éclair avec point de flèche àl'intérieur d'un triangle
équilatéral est utilisépour alerter l'utilisateur de la présence à
l'intérieur du coffret de “voltage dangereux”non isoléd'ampleur
suffisante pour constituer un risque d'éléctrocution.
The exclamation point within an equilateral triangle is intended to
alert the user of the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the appliance.
Le point d'exclamation àl'intérieur d'un triangle équilatéral est
employépour alerter les utilisateurs de la présence d'instructions
importantes pour le fonctionnement et l'entretien (service) dans le
livret d'instruction accom
p
a
g
nant l'a
pp
areil.

Part No. 0009427 Rev. A 1/04
©2004 LOUD Technologies Inc. All Rights Reserved.
3
What me, read a manual?
Before you begin, please make sure you read the Safety Instructions on page 2 and
Getting Started on page 4.
Your new TAPCO®T•231 is designed to set up quickly and operate easily. We know it’s
often seen as a sign of weakness to read a manual, along with asking for directions when
lost, but maybe you can read the rest when nobody is looking.
It is important to keep your receipt in a safe place, and not a bad idea to write your
product information here for future reference (i.e., insurance claims, tech support, return
authorization, etc.).
Duration Per Day Sound Level dBA, Typical
In Hours Slow Response Example
8 90 Packed garage concert
6 92
4 95 VW Bus Peace Train
3 97
2 100 Cranked psychedelic tunes
1.5 102
1 105 High speed chase on C.H.I.P.s
0.5 110
0.25 or less 115 Loudest parts at a Heavy Metal concert
Product Serial #:
Purchased at:
Date of purchase:
18. Exposure to extremely high noise levels may cause permanent
hearing loss. Individuals vary considerably in susceptibility to
noise-induced hearing loss, but nearly everyone will lose some
hearing if exposed to sufficiently intense noise for a period of
time. The U.S. Government’s Occupational Safety and Health
Administration (OSHA) has specified the permissible noise
level exposures shown in the following chart.
According to OSHA, any exposure in excess of these permissible limits
could result in some hearing loss. To ensure against potentially dangerous
exposure to high sound pressure levels, it is recommended that all persons
exposed to equipment capable of producing high sound pressure levels
use hearing protectors while the equipment is in operation. Ear plugs or
protectors in the ear canals or over the ears must be worn when operating
the equipment in order to prevent permanent hearing loss if exposure is in
excess of the limits set forth here.

4
Getting Started
The following steps will help you set up your T•231, and get the
levels just right.
SETTINGS:
1. Be sure the T•231’s POWER switch is off.
2.
Set all the sliders to their center positions and all the
switches out.
CONNECTIONS:
1. Using balanced or unbalanced cables, connect
your mixer’s main outputs to the T•231’s inputs,
and the T•231’s outputs to your amplifer’s (or
powered speakers’) inputs.
If you are using the T•231 in a channel’s insert,
connect your mixer’s channel inserts to your
T•231’s INPUTs and OUTPUTs.
Note: The T•231 31-Band Graphic
Equalizer is designed to be inserted
“in-line”with the signal as a
serial device. This means that the
entire signal is routed through the
processor, in contrast to a parallel
device where the processed signal is mixed back
with the unprocessed signal, like a reverb or echo.
2. Connect the cables using either XLR or 1/4”
TRS connectors (balanced), or 1/4”TS or RCA
connectors (unbalanced).
•The XLR, TRS, and RCA inputs for each channel
are wired in parallel. Use only one input per channel.
•The XLR, TRS, and RCA outputs for each channel
are wired in parallel.
•The balanced XLR connectors are wired as
follows:
Pin 1 = shield (ground)
Pin 2 = hot (+)
Pin 3 = cold (–)
•The 1/4”TRS connectors are wired as follows:
Tip = hot (+)
Ring = cold (–)
Sleeve = shield (ground)
3. Plug all the sound system components into suitable
AC outlets, properly grounded and capable of
delivering adequate current.
4. Turn all the equipment on. If you are monitoring the
signal through speakers, turn the power amplifier
on last to avoid getting any pops or thumps
through your speakers.
SET THE CONTROLS:
1. Make sure your signal source is turned up and
delivering signal to the T•231. The signal should
pass through the T•231 unaffected because the
CHAN 1 and 2 BYPASS buttons are out and the
signal processing circuitry is bypassed.
2. Push in the CHAN 1 and 2 BYPASS buttons to
enable the graphic equalizer circuits.
3. You can turn up and down each individual slider
and hear how it affects the sound.
4. You can turn up and down the input LEVEL controls
to make it louder or softer. When the LEVEL control
is at the center detent, it is at unity gain (it doesn’t
boost or cut the signal).
Things To Remember:
•When you shut down your
equipment, turn off the amplifiers
first. When powering up, turn on the
amplifiers last.
•Save the shipping box and
packing material! You may need it
someday.
LOOK
CLOSER

5
Don’t forget to visit our website at www.tapcogear.com
for more information about this and other TAPCO products.
Safety Instructions................................................................2
Getting Started....................................................................4
Introduction..........................................................................6
Hookup Diagrams................................................................8
Typical Hookup: In-line with Main Outputs .....................8
Alternate Hookup: Individual Channel or Main Inserts ..8
T•231 Features ....................................................................9
FRONT PANEL FEATURES .................................................9
1. EQ Sliders ...............................................................9
2. Input LEVEL ............................................................9
3. HI-PASS ..................................................................9
4. LOW-PASS ..............................................................9
5. BYPASS....................................................................9
6. CLIP ........................................................................9
7. RANGE ...................................................................9
8. POWER ...................................................................9
REAR PANEL FEATURES..................................................10
9. Line Cord Socket and Fuse................................10
10. AC Select Switch ..............................................10
11. GND LIFT Switch ................................................10
12. OUTPUTS .............................................................10
13. INPUTS.................................................................10
GENERAL PRECAUTIONS AND CONSIDERATIONS .....11
Rack Mounting........................................................11
Thermal Considerations .........................................11
AC Power Considerations......................................11
Appendix A: Service Information ....................................12
Warranty Service ..........................................................12
Troubleshooting ............................................................12
Repair ............................................................................13
Appendix B: Connections ................................................14
Appendix C: Technical Info..............................................15
T•231 Specifications ....................................................15
T•231 Block Diagram ...................................................16
Frequency Chart..........................................................18
TAPCO LIMITED WARRANTY...............................................19
Contents

6
Introduction
Thank you for choosing a TAPCO®Tweeq™31-band graphic
equalizer by Mackie®. The TAPCO product line hails back to the
days of TAPCO Corporation, Greg Mackie’s first company. TAPCO
revolutionized the audio industry back in 1969 with the very first 6-
channel mixer specifically designed for keyboards and rock ‘N’roll PA.
In essence, TAPCO redefined the price performance ratio and
made high-quality professional audio mixers accessible to virtually
anyone.
Today, TAPCO is reborn with the same ideals and is backed
by the world-class engineering and manufacturing horsepower of
Mackie. The TAPCO T•231 is the first graphic equalizer in the TAPCO by
Mackie
®
family.
About Graphic Equalizers
The tone controls on your home stereo system typically have a bass and treble control,
and sometimes a midrange control, that you use to boost or cut a broad band of
frequencies. When you leave the controls in the center position, they do nothing.
A graphic equalizer works in much the same way, except that it has many more controls
that operate over much narrower frequency bands. The T•231 has 31 controls that boost or
cut different frequencies, each centered on ISO standard frequencies ranging from 20 Hz
to 20 kHz and affecting 1/3 of an octave.
Constant Q Design
The T•231 is designed with constant Q filters. The Q of a filter refers to its quality. A filter
with a low Q affects a broader band of frequencies than a filter with a high Q (Q=fc/BW, for
you technoids!). Constant Q means that, as a slider is boosted or cut, the bandwidth of the
filter (the “skirt”of the affected frequencies) remains the same. Lower quality proportional
Q filters have a broader bandwidth as the filter is boosted or cut, which can extend out to
an octave or more.
Whazzit Used For?
There are a number of uses for graphic equalizers in a sound system. They can be used
to correct the frequency response of a loudspeaker, or to adjust for resonant peaks and
dips in a room. Sometimes they are used to simply bring out the characteristics of a voice or
instrument to improve the intelligibility and articulation of the sound.
In any case, please remember that a graphic equalizer is a tool that can be used to
improve the overall sound, but it cannot make up for frequency response deficiencies
caused by poor system design or poor acoustics. Try and get the best possible sound
from the system before attempting to use equalization by paying attention to proper gain
structure and loudspeaker placement. Often times just moving a loudspeaker to a different
position can have a dramatic effect on the overall sound in the room.
Probably the most common use of a graphic equalizer is placing it in-line between the
mixing board’s main outputs and the power amplifier inputs (see hookup diagram on page 8) .
When used with a real-time analyzer and pink noise generator, it can be used to fine tune
the acoustic frequency response and get it as flat as possible in a room.
TAPCO version of Greg
TAPCO van (a.k.a. micro bus)

7
However, often times a perfectly flat frequency response is not what you want in a live
sound application. For example, if the low-frequency response of the loudspeakers only
extends to 50 Hz, there is no need to amplify the frequencies in the lowest octave of the
audio frequency range, 20 Hz to 40 Hz. You can use the T•231 to roll off these frequencies,
which reduces the drain on the amplifier and provides more power to amplify the higher,
more useful frequencies.
You might want to boost the higher frequencies a bit to add brightness and sizzle to the
sound. If the sound system is for the speaking voice, boosting the mid frequencies around
2-4 kHz can improve the intelligibility of the voice. Boosting 125 Hz, 250 Hz, and 16 kHz can
improve a vocal. Try as you might to eliminate it, there may still be a residual 60-cycle hum
in the speakers. You can use the 63 Hz slider to notch down the hum (the 125 Hz slider can
help eliminate residual buzz).
A graphic equalizer can be used to reduce feedback. If you don’t have a real-time
analyzer to identify the peaks that cause the feedback, you can do a fairly good job by
ear using the following procedure.
1. Set all the sliders on the T•231 to the center position (zero).
2. Slowly turn up the master volume on the mixer until feedback just begins to occur.
You can usually hear a soft ringing sound that gradually increases in volume. BUT BE
CAREFUL! Feedback can occur quickly and become very LOUD, very fast.
3. Cut the appropriate slider, corresponding to the feedback frequency, until feedback
stops. It may take some practice to identify the frequency where the feedback is
occurring, but your accuracy will improve the more familiar you become with it.
4. Repeat until you can’t isolate a specific frequency in the feedback.
This procedure helps to minimize the resonant peaks in the room. It’s a little more difficult
to identify and adjust for dips in the room response. This is best done from experience
listening for gaps in the sound of particular instruments or voices. Once you’ve identified
them, boost the slider for that particular frequency range by 3 to 6 dB to help smooth the
frequency response.
Another application for a graphic equalizer is patching it into a channel insert to
enhance the sound or change the tonal characteristics of a vocal or instrument (see
hookup diagram). The Sound Frequency chart on page 18 is a good reference to locate
the frequency ranges of particular voices and instrument.
The Tweeq Series™of processors are powerful and tough. They are designed to
withstand the punishing rigors of the road and continue to perform day after day, year
after year.
Here’s a quick glance at the features packed into the T•231:
•2-channel 31-band graphic equalizer with constant Q circuitry and great sound quality
•Switchable 6 and 12 dB control range for wide or fine tweaking
•High-pass filter @ 40 Hz to remove unwanted low frequencies
•Low-pass filter @ 16 kHz to remove unwanted high frequencies
•Bypass switch allows quick A/B comparisons
•Independent signal clip indicators on each channel
•Input gain control for EQ signal compensation
•Balanced 1/4" TRS and XLR, and unbalanced RCA input and output jacks
•Selectable line voltage

8
Hookup Diagrams
Typical Hookup:
In-line with Main Outputs
WARNING: TOREDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSETHIS EQUIPMENT TO RAIN OR MOISTURE. DONOT REMOVE COVER.
NO USER SERVICEABLEPARTS INSIDE. REFER SERVICINGTO QUALIFIED PERSONNEL.
AVIS: RISQUE DE CHOC ELECTRIQUE — NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
UNBAL BALBAL/UNBAL
BAL/UNBAL
BAL
OUT IN
GND
LIFT
315mA 250V
T
SERIAL /DATE CODE OUT IN
OUT IN
OUT IN
UNBAL BAL BAL
OUT IN
OUT IN
CHANNEL 1
CHANNEL 2
RISK OF FIRE
REPLACE FUSE AS MARKED WARNING
NO
OUTDOOR USE
BROUGHTTOYOUBYTHEGROOVYFOLKSINWOODINVILLE,WA,USA
MANUFACTUREDINCHINA
•
FABRIQUEAUCHINE
"TAPCO"AND"MACKIE"AREREGISTEREDTRADEMARKSOF
LOUDTECHNOLOGIESINC.•COPYRIGHT©2003
WWW.TAPCOGEAR.COM
115V
AC100-120V,
60Hz
AC
200-240V,
50HZ
RATED
INPUT:
12.5W
TO CHANNEL OR MAIN INSERT
RETURN
SEND
TO CHANNEL OR MAIN INSERT
RETURN
SEND
WARNING: TOREDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSETHIS EQUIPMENT TO RAIN OR MOISTURE. DONOT REMOVE COVER.
NO USER SERVICEABLEPARTS INSIDE. REFER SERVICINGTO QUALIFIED PERSONNEL.
AVIS: RISQUE DE CHOC ELECTRIQUE —NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
UNBAL BALBAL/UNBAL
BAL/UNBAL
BAL
OUT IN
GND
LIFT
315mA 250V
T
SERIAL /DATE CODE OUT IN
OUT IN
OUT IN
UNBAL BAL BAL
OUT IN
OUT IN
CHANNEL 1
CHANNEL 2
RISK OF FIRE
REPLACE FUSE AS MARKED WARNING
NO
OUTDOOR USE
BROUGHTTOYOUBYTHEGROOVYFOLKSINWOODINVILLE,WA,USA
MANUFACTUREDINCHINA
•
FABRIQUEAUCHINE
"TAPCO"AND"MACKIE"AREREGISTEREDTRADEMARKSOF
LOUDTECHNOLOGIESINC.•COPYRIGHT©2003
WWW.TAPCOGEAR.COM
115V
AC100-120V,
60Hz
AC
200-240V,
50HZ
RATED
INPUT:
12.5W
FROM MIXING
CONSOLE LEFT AND
RIGHT MAIN OUTPUTS
TO POWER AMPLIFIER OR
POWERED SPEAKERS INPUTS
Alternate Hookup:
Individual Channel or Main Inserts

9
T•231 Features
5. BYPASS
This button effectively disables the EQ circuits. You
can use this button to compare the EQ’d signal to
the unprocessed signal. When the BYPASS button is
pushed in, the LED below the BYPASS button lights.
6. CLIP
This LED lights when the output signal is within 5 dB
of clipping. It is okay if the CLIP LED blinks occasionally,
but if it blinks frequently or stays lit all the time, turn
down either the LEVEL control or the output signal
from the mixer or other device immediately preceding
the T•231.
7. RANGE
This determines the maximum boost and cut of
the EQ sliders, either ±12 dB or ± 6 dB (pushed in). The
corresponding LED below the RANGE button indicates
the setting.
The 12 dB setting provides more boost and cut if it
is needed for more drastic EQ requirements
. The 6 dB
setting provides less boost and cut, but allows you to
fine tune the controls with more precision.
8. POWER
Use this switch to turn the T•231 on and off. The LED
above the switch lights when the power is on.
FRONT PANEL FEATURES
The controls for Channels 1 and 2 are the same, so
these descriptions apply to both channels.
1. EQ Sliders
When the EQ sliders are in the center position, they
have no effect on the signal. Move a slider up or
down to boost or cut a particular frequency by up to
±12 dB (±6 dB when the RANGE switch is set to 6 dB).
2. Input LEVEL
Use the Input LEVEL control to adjust the gain of the
signal as it passes through the T•231. When the Input
LEVEL control is in the center position, it provides no
gain (unity gain). When the slider is all the way down
the signal is off (-∞), and all the way up provides 17 dB
of gain.
3. HI-PASS
This button is used to roll-off the frequencies below
40 Hz. The LED below the button lights to indicate
when the HI-PASS filter is turned on.
This is useful to reduce stage rumble (low-frequency
noise from footsteps picked up by microphones on
stage) and microphone-handling noise.
If the T•231 is used with monitor speakers, turning
on this button can reduce the muddiness caused by
the lows from the stage monitors feeding back into
the main output through the microphones.
4. LOW-PASS
Use this button to roll-off the frequencies above
16 kHz.
The LED below the button lights to indicate
when the LOW-PASS filter is turned on.
This is useful to remove hiss and high-frequency
noise from the signal.
LEVEL
LEVEL
1
2
+17
0
-12
+12
+12
-12
+17
0
CLIP
RANGE
6dB 12dB
HI-PASS LOW -PASS
40Hz 16kHz
CLIP 6dB 12dB40Hz 16kHz
BYPASS
RANGEHI-PASS LOW -PASS BYPASS
POWER
ON
OFF
DUAL 31-BAND GRAPHIC EQUALIZER
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 800250 630 1.6k 4k3.15k 8k 16k 20k
BY
BY
T•231
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 800250 630 1.6k 4k3.15k 8k 16k 20k
1
28
1
45
3
27
6

10
REAR PANEL FEATURES
9. Line Cord Socket and Fuse
Here is where you connect the detachable line
cord that came in the box with your T•231. Plug
the other end of the line cord into an AC outlet
properly configured with the voltage required for your
particular model (see AC Select Switch next).
The fuse is located behind the fuse cover, at the
bottom of the IEC socket. See the “Troubleshooting”
section on page 12 for information about replacing
the fuse.
10. AC Select Switch
Set this switch to the correct voltage setting for the
country you are in, 115 VAC or 230 VAC.
Note: The T•231 is shipped with the AC Select
switch set to the 230 VAC position. If you are in a
country that uses 100-120 VAC, remove the cover
plate with a phillips-head screwdriver and set the
switch to the 115 VAC position. A 315 mA fuse
is used for both voltages (115V/230V). See the
“Troubleshooting”section on page 12 for instructions
on replacing the fuse.
11. GND LIFT Switch
When the switch is in the GND position, the audio
ground is electrically connected to the chassis
“safety”ground. Normally, this is how the switch is set.
However, occasionally a ground loop can be
created in a system where the signal ground is
connected to chassis ground, which can cause a
hum or buzz to appear in the audio signal. If this is
the case, try moving the switch to the LIFT position to
eliminate the hum or buzz.
12. OUTPUTS
Three types of connectors are provided for the
outputs —balanced male XLR and 1/4”TRS (Tip-
Ring-Sleeve), and unbalanced RCA. These balanced
outputs are in parallel, and provide exactly the same
signal on all three outputs, regardless of which input
jack is used. You can connect either a balanced TRS
connector or an unbalanced TS connector to the 1/4”
output jack.
13. INPUTS
Three types of connectors are provided for the
inputs —balanced female XLR and 1/4”TRS (Tip-Ring-
Sleeve), and unbalanced RCA. These inputs are in
parallel, so do not connect more than one signal at
a time to the input jacks for each channel.
You can
connect either a balanced or an unbalanced
signal to
the 1/4”input jack.
See “Appendix B: Connections”on page 14 for
information on input and output connection wiring.
WARNING: TO REDUCETHE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS EQUIPMENTTO RAIN OR MOISTURE. DO NOT REMOVE COVER.
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.
AVIS : RISQUEDE CHOC ELECTRIQUE —NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
UNBAL BALBAL/UNBAL
BAL/UNBAL
BAL
OUT IN
GND
LIFT
315mA 250V
T
SERIAL /DATE CODE OUT IN
OUT IN
OUT IN
UNBAL BAL BAL
OUT IN
OUT IN
CHANNEL 1
CHANNEL 2
RISK OF FIRE
REPLACE FUSE AS MARKED WARNI NG
NO
OUTDOOR USE
BROUGHTTOYOUBYTHEGROOVYFOLKSINWOODINVILLE,WA,USA
MANUFACTUREDINCHINA
•
FABRIQUEAUCHINE
"TAPCO"AND"MACKIE"AREREGISTEREDTRADEMARKSOF
LOUDTECHNOLOGIESINC.•COPYRIGHT©2003
WWW.TAPCOGEAR.COM
AC100-120V,
60Hz
AC
200-240V,
50HZ
RATED
INPUT:
12.5W
115V
910
11
12 13

11
GENERAL PRECAUTIONS AND CONSIDERATIONS
Rack Mounting
The T•231 is designed to be mounted in a standard
rack. It requires two rack spaces (2U = 3.5”). It also
requires 7.5”depth inside the rack, not counting the
rear connectors. When designing your rack, put the
heavier items at the bottom and the lighter items
toward the top.
Secure the front panel of the T•231 to the front of
the rack using four screws with soft washers to prevent
scratching the panel.
Thermal Considerations
Avoid mounting the T•231 directly over devices
that produce heat, such as power amplifiers. As with
all electronic components, it is best to provide cool air
circulation around the T•231 to avoid overheating. The
ambient temperature should not exceed 113˚F (45˚C).
AC Power Considerations
Be sure the T•231 is plugged into an AC outlet that
is able to supply the specified voltage, and the AC
Select switch is set to the correct voltage.
Be sure the AC outlet can supply enough current
to allow full power operation of all the components
plugged into it, especially if there are power amplifiers
plugged in. The outlet should be a three-prong socket
that matches the power cord.
WARNING: Bypassing the plug’s
safety ground pin can be
dangerous. Don’t do it!

12
Appendix A: Service Information
Warranty Service
Details concerning Warranty Service are spelled
out in the Warranty section on page 19.
If you think your T•231 has a problem, please do
everything you can to confirm it before calling for
service. Doing so might save you from the deprivation
of your equalizer and the associated suffering.
These may sound obvious to you, but here are
some things you can check. Read on.
Troubleshooting
No Power
•Our favorite question: Is it plugged in? Make sure
the AC outlet is live (check with a tester or lamp).
•Our next favorite question: Is the POWER switch
on? If not, try turning it on.
•Is the red LED above to the POWER switch
illuminated? If not, make sure the AC outlet is live.
If so, refer to “No Sound”below.
•Is the fuse blown? If the POWER LED on the front
panel is not illuminated and you are certain that
the AC outlet is live, if is possible the fuse has blown.
To remove and replace the fuse:
1. Disconnect the line cord from the IEC socket.
2. Remove the fuse drawer by prying it open with a
small screwdriver. It will slide all the way out.
FUSE
3. Remove the fuse and replace it with an
equivalent-type fuse:
315 milliamp slo-blo (T315 A/250 V)
Note: The same fuse is used for both 115 VAC and
230 VAC operation.
4. Replace the fuse drawer by pushing it all the way
back into the IEC socket.
5. Reconnect the line cord and turn the POWER
switch on.
If two fuses blow in a row, then something is wrong.
See the “Repair”section on the next page to find
out what to do.
No Sound
•Is the signal source turned up? Make sure the
signal level from the mixing console (or whatever
device immediately precedes the T•231) is high
enough to produce sound through the system.
•Are you using the T•231 with an insert plug in an
insert jack? Make sure that you are using an insert
cable, and not a mono Y-cable.
Poor sound
•Is it loud and distorted? Turn down the signal
coming from the mixer or signal source.
•Is the input connector plugged completely into
the jack? Make sure all connections are good and
sound.
•Switch the BYPASS switch in and out to compare
the sound with the equalizer in the signal path and
out of the signal path. This can help determine if
the problem is with the T•231 or elsewhere in the
system.
Noise/Hum
•Check the signal cable between the mixer and
the T•231. Make sure all connections are good
and sound.
•Make sure the signal cable is not routed near AC
cables, power transformers, or other EMI-inducing
devices.
•Is there a light dimmer or other SCR-based device
on the same AC circuit as the T•231 ? Use an AC
line filter, or plug the T•231 into a different AC
circuit.

13
5. Include a legible note stating your name, shipping
address (no P.O. boxes), daytime phone number,
RA number, and a detailed description of the
problem, including how we can duplicate it.
6. Write the RA number in BIG PRINT on top of the box.
Units sent to us without the RA number will be refused.
7. Ship the T•231 to us. We suggest insurance for all
forms of cartage. Ship to this address:
TAPCO
SERVICE DEPARTMENT
16220 Wood-Red Road NE
Woodinville, WA 98072
8. We’ll try to fix the T•231 within five business days.
Ask Tech Support for the latest turn-around times
when you call for your RA number. The T•231
must be packaged in its original packing box,
and must have the RA number on the box. Once
it’s repaired, we’ll ship it back the same way in
which it was received. This paragraph does not
necessarily apply to non-warranty repair.
Repair
Service for TAPCO products is available from one
of our authorized domestic service centers or at our
factory, located in sunny Woodinville, Washington.
Service for TAPCO products living outside the United
States can be obtained through local dealers or
distributors.
If your T•231 needs service, follow these instructions:
1. Review the preceding troubleshooting suggestions.
Please.
2. Call Tech Support at 1-877-827-2669, 7 am to 5 pm
PST, to explain the problem and request an RA
(Return Authorization) number. Have your T•231’s
serial number ready. You must have an RA number
before you can obtain warranty service at the
factory or an authorized service center.
3. Keep this owner’s manual and the detachable line
cord. We don’t need them to repair the T•231.
4. Pack the T•231 in its original package, including
endcaps and box. This is very important. When
you call for the RA number, please let Tech
Support know if you need new packaging. You
can order new packaging through our parts
department. LOUD Technologies is not responsible
for any damage that occurs due to non-factory
packaging.
Lonely? Looking for that special someone? Do you have a question about
your TAPCO product?
Please call our Technical Support folks at 1-877-827-2669, Monday to Friday, from 7 am to 5 pm PST.
After hours, visit www.tapcogear.com and look under Support, or e-mail us at [e-mail]

14
Appendix B: Connections
1/4" TS Phone Plugs and Jacks
“TS”stands for Tip-Sleeve, the two connection
points available on a mono 1/4" phone jack or plug.
They are used for unbalanced signals.
SLEEVE
TIP
TIP
SLEEVE
TIP
SLEEVE
1/4" TS Unbalanced Wiring:
Sleeve = Shield
Tip = Hot (+)
1/4" TRS Insert Plugs and Jacks
When patching the T•231 into a channel’s
insert jack, you may need to use a special 1/4" TRS
connector that uses the tip to send the signal to the
T•231, and the ring to return the signal to the channel.
The sleeve is the common ground (earth) for both
signals. These are both unbalanced signals.
“tip”
This plug connects to the
Channel Insert jack “ring”
tip
ring
sleeve
SEND to processor
RETURN from processor
(TRS plug)
1/4" TRS Insert Wiring:
Sleeve = Ground
Tip = Send
Ring = Return
RCA Plugs and Jacks
RCA-type plugs (also known as phono plugs)
and jacks are often used in home stereo and video
equipment and in many other applications. They are
unbalanced and electrically equivalent to a 1/4" TS
phone plug.
TI
P
SLEEVE
TIPSLEEVE
RCA Unbalanced Wiring:
Sleeve = Shield
Tip = Hot
XLR Connectors
The inputs and outputs use 3-pin male and female
XLR connectors. They are wired as follows, according
to standards specified by the AES (Audio Engineering
Society).
2
31
SHIELD
COLD
HOT
SHIELD
COLD
HOT
3
2
1
XLR Balanced Wiring
Pin 1 = Shield
Pin 2 = Hot (+)
Pin 3 = Cold (–)
1/4" TRS Phone Plugs and Jacks
“TRS”stands for Tip-Ring-Sleeve, the three
connection points available on a stereo 1/4" or
balanced phone jack or plug. TRS jacks and plugs are
used for balanced signals.
SLEEVE
TIP
SLEEVE
TIP
RING
RING
TIP
SLEEVERING
1/4" TRS Balanced Wiring:
Sleeve = Shield
Tip = Hot (+)
Ring = Cold (–)

15
Appendix C: Technical Info
T•231 Specifications
Frequency Response
20 Hz to 20 kHz (+0, –1 dB)
20 Hz to 50 kHz (+0, –3 dB)
Audio Input
Type: Active balanced XLR
and 1/4" jacks
Unbalanced RCA jack
Impedance: 20 kΩbalanced
15 kΩunbalanced
Maximum Input Level: +21 dBu balanced and
unbalanced
Audio Output
Type: Active balanced XLR and
1/4" jacks
Unbalanced RCA jack
Impedance: <600 Ω
Maximum Output Level: +18 dBu
THD+N @ 1 kHz, +4 dBu: 0.02% @ 1 kHz
(all sliders at center position)
Noise and Hum, unity gain:
< –93 dBu
Crosstalk @ 1 kHz: < –103 dBu
Common Mode Rejection:
> 60 dB
Graphic EQ
Type: 1/3-octave Constant Q
Frequency Range: 20 Hz to 20 kHz
in 31 third-octave bands
(ISO center frequencies)
Sliders: 20 mm with center detent
Level: Off (∞) to +17 dB
Hi-Pass: 40 Hz @ 12 dB/octave
Low-Pass: 16 kHz @ 12 dB/octave
Bypass:
Bypasses the graphic equalizer,
Hi-Pass, and Low-Pass
filter sections
Range: ±6 dB or ±12 dB
Indicators
HI-PASS LED
LOW-PASS LED
CLIP LED
BYPASS LED
6 dB/12 dB Range LEDs
POWER LED
AC Power and Current Requirements
Power Consumption: 12.5 watts
AC Operating Voltages:
U.S. 120 VAC, 60 Hz
Europe 240 VAC, 50 Hz
Japan 100 VAC, 50/60 Hz
Korea 220 VAC, 60 Hz
Fuse: 315 mA @ 100-240 VAC
Physical Dimensions and Weight
Height: 3.5 in/89 mm
Width: 19.0 in/483 mm
Depth: 8.7 in/220 mm
Weight: 9.5 lb/4.3 kg
Disclaimer
Since we are always striving to make our products
better by incorporating new and improved materials,
components, and manufacturing methods, we
reserve the right to change these specifications at
any time without notice.

16
T•231 Block Diagram
This outlines the signal flow inside the T•231.
BALANCED
LINE INPUT
(TRS)
UNBALANCED
LINE INPUT
(RCA)
BALANCED
LINE INPUT
(XLR-F)
1
2 3
CHANNEL 1
LEVEL
GRAPHIC EQ
FILTERS
RANGE
HI-PASS
FILTER
ON
OFF
6 dB
6 dB 12 dB
12 dB
LOW-PASS
FILTER
BYPASS
ON
OFF
CLIP
DETECT
CLIP
CHANNEL 1
CHANNEL 1 CHANNEL 2
BALANCED
LINE OUTPUT
(TRS)
UNBALANCED
LINE OUTPUT
(RCA)
BALANCED
LINE OUTPUT
(XLR-F)
1
2 3
CLIP
DETECT
CLIP
BALANCED
LINE INPUT
(TRS)
UNBALANCED
LINE INPUT
(RCA)
BALANCED
LINE INPUT
(XLR-F)
1
2 3
CHANNEL 2
LEVEL
GRAPHIC EQ
FILTERS
RANGE
HI-PASS
FILTER
ON
OFF
6 dB
6 dB 12 dB
12 dB
LOW-PASS
FILTER
BYPASS
ON
OFF
CHANNEL 2 BALANCED
LINE OUTPUT
(TRS)
UNBALANCED
LINE OUTPUT
(RCA)
BALANCED
LINE OUTPUT
(XLR-F)
1
2 3
+
–VDC
TOROIDAL POWER
TRANSFORMER
POWER
LED
TA P C O T•231 BLOCK DIAGRAM 12.24.03
115V ↔230V
FUSE POWER AC SELECT
GND LIFT
10
7
8
1
5
6
4
3
9
13
2
7
1
5
6
4
3
13
2
11
12 12

17
LEVEL LEVEL
1 2
+17
0
-12
+12
+12
-12
+17
0
CLIP
RANGE
6dB 12 dB
HI -PASS LOW-PASS
40Hz 16kHz
CLIP 6dB 12 dB40Hz 16kHz
BYPASS
RANGEHI -PASS LOW-PASS BYPASS
POWER
ON OFF
DUAL 31-BAND GRAPHIC EQUALIZER
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 800250 630 1.6k 4k3.15k 8k 16k 20k
BY
BY
T•231
20 31.5 50 100 200 500 1.25k 2.5k 6.3k 12.5k25 40 80 160 400 1k 2k 5k 10k63 125 315 800250 630 1.6k 4k3.15k 8k 16k 20k
1
28
1
45
3
27
6
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICINGTO QUALIFIED PERSONNEL.
AVIS: RISQUE DE CHOC ELECTRIQUE —NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
UNBAL BALBAL/UNBAL
BAL/UNBAL
BAL
OUT IN
GND LIFT
315mA 250V
T
SERIAL /DATE CODE OUT IN
OUT IN OUT IN
UNBAL BAL BAL
OUT IN
OUT IN
CHANNEL 1 CHANNEL 2
RISK OF FIRE
REPLACE FUSE AS MARKED WARNING
NO
OUTDOOR
USE
BROUGHTTOYOUBYTHEGROOVYFOLKSIN WOODINVILLE, WA, USA
MANUFACTUREDINCHINA
•
FABRIQUEAUCHINE
"TAPCO"AND"MACKIE"AREREGISTERED TRADEMARKSOF
LOUDTECHNOLOGIESINC.•COPYRIGHT©2003
WWW.TAPCOGEAR.COM
AC100-120V,
60Hz
AC
200-240V,
50HZ
RATED
INPUT:
12.5W
115V
910
11
12 13

18
Frequency Chart
This chart shows the frequency range covered by various instruments and voices.
CDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABCDEFGABC
VOCAL
25 31 40 50 62 80 100 125 160 200 250 320 400 500 640 800 1K 1.3K1.6K 2K 2.5K 3.1K 4K 5K 6.2K 8K 10K 13K 16K 20K
Soprano
Contralto
Baritone
Bass
WOODWIND
Piccolo
Flute
Oboe
Clarinet in B flat or A
Clarinet in E flat
Bass Clarinet
Basset Hom
English Horn
Bassoon
Double Bassoon
BRASS
Soprano Saxophone
Alto Saxophone
Tenor Saxophone
Baritone Saxophone
Bass Saxophone
Trumpet in C
Trumpet in F
Alto Trombone
Tenor Trombone
Bass Trombone
Tuba
Euphonium
STRINGS
Violin
Viola
Cello
Double Bass
Guitar
KEYBOARDS
Pianoforte
Organ
PERCUSSION
Celesta
Timpani
Xylophone
FREQUENCY
2520 31 40 50 62 80 100 125 160 200 250 320 400 500 640 800 1K 1.3K 1.6K 2K 2.5K 3.1K 4K 5K 6.2K 8K 10K 13K 16K 20K
Typical Frequency of each Instrument and Voice
Middle C
Human Hearing Range
20

19
TAPCO LIMITED WARRANTY
A. LOUD Technologies Inc. warrants all materials,
workmanship and proper operation of this TAPCO
product for a period of one year from the original
date of purchase. If any defects are found in the
materials or workmanship, or if the product fails to
function properly during the applicable warranty
period, LOUD Technologies, at its option, will repair
or replace the product. This warranty applies only
to equipment sold and delivered within the U.S. by
LOUD Technologies or its authorized dealers.
B. Failure to register online or return the product
registration card will not void the 1-year warranty.
C. Service and repairs of TAPCO products are to be
performed only at the factory, OR at a factory-
authorized service center. Unauthorized service,
repairs, or modification will void this warranty.
D. To obtain service, please follow the instructions
found on page 13.
E. LOUD Technologies Inc. and Authorized TAPCO
Service Centers reserve the right to inspect any
products that may be the subject of any warranty
claims before repair or replacement is carried
out. LOUD Technologies and Authorized TAPCO
Service Centers may, at their option, require
proof of the original date of purchase in the form
of a dated copy of the original dealer’s invoice
or sales receipt. Final
determination of warranty
coverage lies solely with
LOUD Technologies Inc. or
its Authorized Service Centers.
F. TAPCO products returned to LOUD Technologies
and deemed eligible for repair or replacement
under the terms of this warranty will be repaired
or replaced within thirty days of receipt by
LOUD
Technologies
at our rainforest factory complex.
LOUD Technologies may use refurbished parts for
repair or replacement of any product. Products
returned to
LOUD Technologies that do not meet
the terms of this Warranty will be repaired and
returned C.O.D. with billing for labor, materials,
return freight, and insurance. Products repaired
under warranty at the factory will be returned
freight prepaid by
LOUD Technologies to any
location within the boundaries of the USA.
G. LOUD Technologies warrants all repairs performed
for 90 days or for the remainder of the warranty
period. This warranty does not extend to damage
resulting from improper installation, misuse,
neglect
or abuse, or to exterior appearance. This
warranty is recognized only if the inspection seals
and serial number on the unit have not been
defaced or removed.
H. LOUD Technologies assumes no responsibility for
the quality or timeliness of repairs performed by
TAPCO Authorized Service Centers.
I. This warranty is extended to the original purchaser
and to anyone who may subsequently purchase
this product within the applicable warranty period.
J. This is your sole warranty. LOUD Technologies Inc.
does not authorize any third party, including any
dealer or sales representative, to assume any
liability on behalf of LOUD Technologies or to make
any warranty for LOUD Technologies Inc.
K. THE WARRANTY GIVEN ON THIS PAGE IS THE SOLE
WARRANTY GIVEN BY LOUD TECHNOLOGIES INC.
AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS
AND IMPLIED, INCLUDING THE WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE WARRANTY GIVEN ON THIS PAGE
SHALL BE STRICTLY LIMITED IN DURATION TO ONE
YEAR FROM THE DATE OF ORIGINAL PURCHASE
FROM AN AUTHORIZED TAPCO DEALER. UPON
EXPIRATION OF THE APPLICABLE WARRANTY PERIOD,
LOUD TECHNOLOGIES SHALL HAVE NO FURTHER
WARRANTY OBLIGATION OF ANY KIND. LOUD
TECHNOLOGIES INC. SHALL NOT BE LIABLE FOR
ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL
DAMAGES THAT MAY RESULT FROM ANY DEFECT IN
THE TAPCO PRODUCT OR ANY WARRANTY CLAIM.
Some states do not allow exclusion or limitation of
incidental, special, or consequential damages or
a limitation on how long warranties last, so some
of the above limitations and exclusions may not
apply to you. This warranty provides specific legal
rights and you may have other rights which vary
from state to state.
Please keep your sales receipt in a safe place.
“Mackie.”and “TAPCO”are registered trademarks
of LOUD Technologies Inc. “Tweeq”is a trademark of
LOUD Technologies Inc.
All other brand names mentioned are trademarks or
registered trademarks of their respective holders, and
are hereby acknowledged.
©2004 LOUD Technologies Inc. All Rights Reserved.

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