cv input mod'd to track at 1v/oct accurately.

The Moog Forum Minimoog Forum
1

Both the Voyager and Phatty need a cv input mod to track at 1v/oct accurately.
has anyone got any technical details on this ?

thanks in advance
David

2

your best bet is to contact Ryan in Moog tech support, but basically it involves soldering a trimmer in series with resistor onto the OS Analog pcb.

3

thanks for the contact i will get in touch with Ryan.
The CP-251 or VX-351 suggestion to attenuate the CV and use your ear is not a good workaround, the problem most def needs to solved inside the voyager or phatty
Im simply amazed that owners have lived with this and not put Moog on notice, the Moogs should be able to track accurately straight out of the box to the 1v/oct industry standard

4

tbh I used my VOS with the CP-251 / VX-351 workaround for a while & it wasn’t really a problem once I’d trimmed it accurately & just left it set, but it’s certainly well worth getting the mod done IMHO to free CP & VX up & ensure accurate pitch tracking indefinitely.

5

The CP-251 / VX-351 workaround is just stupid and masks a design flaw

6

It does make sense if you think about it

7

I had my Old School mod’ed by Moog when it was in for some upgrades earlier in the summer and had the resistor replaced with inline resistor/pot and tuned. My Little Phatty (Tribute) already has it (I think they changed the design when Stage began).

Agree that it’s a bit of a bummer considering the emphasis on CVs but easily fixed.

As for CP-251, I don’t have one but prior to fixing mine, I used an attenuator augmented with fixed voltage through a mult in order to BOOST the voltage accordingly (it expected > 1V per octave so an attenuator alone wouldn’t do the trick). All good now.

8

As for CP-251, I don’t have one but prior to fixing mine, I used an attenuator augmented with fixed voltage through a mult in order to BOOST the voltage accordingly (it expected > 1V per octave so an attenuator alone wouldn’t do the trick). All good now.

Now that sounds even dangerous, what say you boosted the voltage too much!

9

As for CP-251, I don’t have one but prior to fixing mine, I used an attenuator augmented with fixed voltage through a mult in order to BOOST the voltage accordingly (it expected > 1V per octave so an attenuator alone wouldn’t do the trick)

yeah, thats how I did it too, prior to getting the mod done…it’s not dangerous or will harm your Moog in any way btw.

10

thanks also found this
the Voyager runs at 0.9375 volts per octave
internally…
From: Amos
Im starting to think that Moog must of used 0.9375 instead of 1V per Octave for a technical reason

11

Yes, and this is due to the fact that it is simpler to attenuate a voltage than it is to boost it…

Say your modular outputs 1 V/oct but is old and the voltage sags to 0.990. If your Moog was expecting 1 V/oct, you would need to add 0.010 V/oct to get proper scaling.

We’re only talking one potentiometer and two sockets otherwise.

12

thanks I have emailed Ken at Kenton to see if he can help with a setting on his convertors
Im really quite desperate to solve this properly

13

are you in the UK ?

the guys at HHB /Source Distribution ( UK Moog distributors ) did the 1V/Oct mod on my VOS for about £85 + VAT I think…turned it around in a fortnight. No problem.