Behringer CAT Reference guide

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985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
The unit is carefully calibrated at the factory. The performance may change over time or due to environmental changes,
and the following recalibration procedures can be used to bring it back to its factory settings. If you do not feel comfortable
doing these calibrations, then we recommend they are done by an experienced audio service technician. This is especially true
for those units that need to be opened to gain access to voltage test points and calibration potentiometers.
CAUTION: Incorrect calibration or damage to the delicate adjustment potentiometers may lead to the unit
becoming inoperable.
Note: Although re-calibration will not invalidate the warranty, any damage caused during re-calibration may invalidate
the warranty.
Legendary Duophonic Analog Synthesizer
with Dual VCOs, 4 Mixable Waveforms,
External Signal Processor, 16-Voice Poly Chain,
and Eurorack Format
Synthesizers and Samplers
CAT
User Support Bulletin
Equipment required
1. Small insulated trimmer screwdriver.
2. Small Phillips screwdriver.
3. A at sheet of cardboard or another insulator as wide as the unit. (This will help prevent damage to the top panel when it is
inverted and resting on the bottom chassis).
4. Digital DC Voltmeter with a scale that can display accurately to 0.001 V.
5. Guitar tuner
6. An external MIDI keyboard of at least 6 octaves including A1 and A7.
7. MIDI cable.
8. Pair of headphones or a sound system to monitor the main output.
Important Note:
Leave the unit turned on for approximately 30 minutes. This will allow the circuits time to warm up and the components and
performance to stabilize with temperature. Without this warm-up time, the calibrations will be inaccurate.
Introduction

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985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
page 2 of 6
Turn over the top panel to gain access to the bottom surface of the printed circuit board (pcb). Be careful not to strain
the ribbon cables. Use the cardboard to protect the top panel.
Caution:
Make sure that the circuit board is not touching any bare metal that may cause a short circuit and damage the unit.
Do not touch the circuit board while the unit is powered up.
Remove the 8 screws holding the top panel to the chassis.
Leave the unit turned on for approximately 30 minutes.
Preparation
Remove all cables and connections to the unit.
Carefully connect the power and turn on the synthsizer.
Follow all steps in the order in which they are presented.
Synthesizers and Samplers
CAT

page 3 of 6
985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
page 3 of 6
Synthesizers and Samplers
CAT
Oscillator Calibration using a guitar tuner:
The positions of knobs and switches are shown in red on Figure 1.
Connect a guitar tuner to the rear panel main 1/4" output.
Please pay special attention to the FREQUENCY knobs of VCO1 and VCO2.
Note that a pitch within 2 to 3 cents of the target frequency should be ne.
Figure 1
Calibration Procedure
VCO1 Calibration
Turn on the VCO1 SAW fader.
On your external keyboard, press the A2 key and adjust the VCO1 OFFSET trimmer (VR42 on the bottom side) while
observing the guitar tuner display (A2-110Hz) (See gure 2 below).

page 4 of 6
985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
page 4 of 6
Synthesizers and Samplers
CAT
VCO2 Calibration
Turn on the VCO2 SAW fader.
On your external keyboard, press the A2 key and adjust the VCO2 OFFSET trimmer (VR44 on the bottom side) while
observing the tuner display (A2-110Hz).
On your external keyboard, press the A5 key and adjust the VCO2 SCALE trimmer (VR43 on the bottom side) while
observing the tuner display (A5-880Hz).
Turn o the VCO1 SAW fader.
Repeat steps 2 and 3 above until both notes are correct in the display. This may need to be repeated several times to
get right.
On your external keyboard, press the A5 key and adjust the VCO1 SCALE trimmer (VR41 on the bottom side) while
observing the tuner display (A5-880Hz).
Figure 2

page 5 of 6
985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
page 5 of 6
Synthesizers and Samplers
CAT
OCTAVE Calibration (factory mode)
Set the Digital Voltmeter to measure a range below 10 VDC.
Locate the test points TP20 and GND on the bottom side. Set the position of the front panel OCTAVE SHIFT to -2.
Figure 3
Repeat steps 2 and 3 above until both notes are correct in the display. This may need to be repeated several times to
get right.
Turn o the VCO2 SAW fader.
This calibration is done after the oscillator calibration. The positions of knobs and switches are shown in red on
Figure 1.

page 6 of 6
985-40000-01170 Rev.A
2021-02-02
Condential, for internal use only. Not to be reproduced.
page 6 of 6
Condential, for internal use only. Not to be reproduced.
Music Tribe accepts no liability for any loss which may be suered by any person who relies either wholly or in part upon any description, photograph, or statement contained herein.
Technical specications, appearances and other information are subject to change without notice. All trademarks are the property of their respective owners. Midas, Klark Teknik,
Lab Gruppen, Lake, Tannoy, Turbosound, TC Electronic, TC Helicon, Behringer, Bugera, Oberheim, Auratone and Coolaudio are trademarks or registered trademarks of Music Tribe Global
Brands Ltd. © Music Tribe Global Brands Ltd. 2021 All rights reserved.
Synthesizers and Samplers
CAT
Connect the negative probe of your voltmeter to GND (shown in gure 3).
Turn o the power and unplug the power connector.
Measure the output voltage. It should read +2.000 V (+/-0.5mV).
Make sure the internal connections are still correctly inserted and secured.
If not, then adjust the OCT ADJ potentiometer (VR45) until the measured output voltage is +2.000 V (+/-0.5mV).
Ret the top panel back into the bottom chassis and secure with all the screws.
This calibration is done after the oscillator calibration. The positions of knobs and switches are shown in red on Figure 1.
Connect a guitar tuner to the rear panel main 1/4" output.
OCTAVE Calibration (user mode)
Turn on the VCO1 SAW fader.
Set the position of the front panel OCTAVE SHIFT to -2. On your external keyboard, press the A4 key and adjust the
FREQUENCY knobs of VCO1 while observing the tuner display (A4 with OCTAVE SHIFT at -2: 110Hz).
Set the position of OCTAVE SHIFT to +2, observe the tuner display (A4 with OCTAVE SHIFT at +2: 1760Hz). If not, then
adjust the OCT ADJ potentiometer (VR45 on the bottom side) until the frequency is correct.
End of Procedure
Connect the positive probe of your voltmeter to TP20 (shown in gure 3).