Date: 11-04-20 Project: Remark:
File: RBDIY-CTSVCOA-1 1 Version: 1 2
Title: CATCH VCO-A DIY HW version: 1 1
REF: Page: 7
Tuning
For good results, please let the VCO warm up for at least 5 minutes!
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Note: A
Note: B
Note: C
Note:
Assembly instruction
To calibrate this VCO, you need either a tuner or a different VCO or keyboard/ ynth. Your second
VCO or YNTH is used as the reference source!
Set the two trimmers (TR1 & TR2) in the middle position (ex works they are in the middle position)
Connect the VCO 1V / Oct inp t to a keyboard CV-note o tp t or Midi interface CV o tp t (1V / Oct o tp ts)
Connect a t ner to the TRI o tp t of the VCO (see note A)
Connect the power s pply ribbon cable to the VCO (make s re the red band is on the right hand side)
T rn on the power and let the VCO warm p for at least 5min (at normal room temperat re – plm 20C)
Set the TUNE knob on the VCO front approximately to the middle position and press C3 on the keyboard.
adj st the TUNE knob f rther ntil the VCO and yo r reference have the same freq ency (Low tracking
adj st. See also note B)
Press the keyboard C3 and meas re or listen to the freq ency. Then press C2 and C1, they m st exactly 1
or 2 oct lower. If the C2 and C1 have a lower freq ency then adj st TR1 slightly p (CW). are the C2 and
C1 higher than each other? Adj st TR1 slightly down (CCW). After every time yo adj sting TR1 yo have
to adj st the TUNE knob again so that yo are back at the same freq as the reference so rce !!
Press the keyboard C5 and meas re or listen to the freq ency. then press C4 and C3. if the C4 and C3
have a lower freq ency then adj st TR1 slightly p (CW). C4 and C3 are higher then adj st TR1 slightly
down (CCW). then check C2 and C1 again. After every time yo adj sting TR1 yo have to adj st the
TUNE knob again so that yo are back at the same freq as the reference so rce !!
Repeat step 7 as many times as necessary ntil all octaves are eq al.
Adj st the TUNE knob on the front 2 oct lower and repeat steps 6 and 7. if they are good go to step 10
Now adj st the TUNE knob on the front 4 oct higher and press C3 on the keyboard. Adj st the TUNE knob
f rther ntil the VCO and yo r reference have the same freq ency
(High tracking adj st. See also note C)
Press the keyboard C3 and then C2 and meas re or listen to the freq ency. Now press C5 and C6. C5 and
C6 have a lower freq ency adj st TR2 than slightly p (CW). If C5 and C6 have a higher freq ency, adj st
TR2 slightly down. After every time yo adj sting TR2 yo have to adj st the TUNE knob again so that yo
are back at the same freq as the reference so rce !!
Repeat step 12 as many times as necessary ntil all octaves are eq al and check C2 and C1 again !
If the low octaves are slightly o t of t ne after step 12, go thro gh step 7 again
If necessary, go thro gh all steps several times if the octaves contin e to have m t al differences
If yo do not have a t ner, connect a second VCO or SYNTH which receives the same CV-Note signal. Mix
the o tp t of both so that yo can hear and compare both signals at the same time ! If yo se a second
VCO, it m st be properly adj sted!
Low tracking adjustment takes place via TR1
High tracking adjustment takes place via TR2 This trimmer only affects high frequencies (approx C5 or
higher) At low frequencies, this trimmer will have no significant influence
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