ray wilson vco versus soundlab vco

loss1234

built up the raw wilson vco (with tempco) last week. it sounds great BUT my particular pcb doesnt seem to be very good at rejecting noise caused by some of my other modules. (a soundlab vco)

now maybe this is because it needs more bypassing? anyone else have similar problems? or should i be ditching my soundlab vco for modular use?

its only when i turn the pitch knob on my soundlab vco that the pitch goes weird on my ray wilson vco

thanks

Pehr · Posted: Wed Dec 05, 2007 8:22 am Post subject:

You should prob check your PSU. What PSU are you using? MFOS +/- 12V?

loss1234 · Posted: Wed Dec 05, 2007 8:55 am Post subject:

brand new psu
power one hbb15-1.5

rock solid psu

i had thought it was my old psu (which was MUCH MUCH worse) but now i am pretty sure its an issue of decoupling or bypassing...which i dont understand much about...

maybe i should use 2 grounds?

v-un-v · Posted: Wed Dec 05, 2007 9:21 am Post subject:

Pehr · Posted: Wed Dec 05, 2007 9:41 am Post subject:

Do you mix the VCO's? or do you modulate one with the other? Confused

loss1234 · Posted: Wed Dec 05, 2007 12:26 pm Post subject: decoupling info??

ONE PSU FOR EACH VCO? hmmm...keep in mind this problem is ONLY happening right now with 2 vcos interacting with each other...i am not hooking up any other modules right now

keep in mind I AM NOT MIXING OR MODULATING THE VCOS WITH EACH OTHER....this drop in pitch happens when i only listen to ONE VCO..

if i have a stable vco like the ray wilson vco and i listen to it alone its fine..but then if i plug in the soundlab vco and turn the psu back on..the ray wilson vco sounds fine UNTIL i start turning knobs ON THE soundlab vco!! its crazy....b Smile

I WILL SAy that the sn voice is less prone to this than the ray wilson vco...but even it seems to be effected by me changing the pitch on the soundlab vco,,,
update..i finished the SN voice today and hooked it up as well...same problem...so its possible that the soundlab vco is pulling down the pitch of the sn voice or ray wilson vco, but this new psu isnt allowing any drop in voltage, so this must be a noise on the line thing...

v-un-v mentioned a separate psu but i think there must be other ways to isolate modules from each other that i just dont understand yet...any info on decoupling would be appreciated

Pehr · Posted: Wed Dec 05, 2007 2:40 pm Post subject:

hmm, I had a similar 'problem', when I 'finished' my MFOS modular. When gradually putting in module after module I noticed that the pitch dropped a little for each module. Shocked

However, I just thought that it was the PSU dropping to its real voltage setting. But it's working fine now. No pitch change affects the others...

I do have my sound labs on a different PSU btw Shocked

but they don't affect each other.

loss1234 · Posted: Wed Dec 05, 2007 3:15 pm Post subject:

interesting....

i think my "problem" is twofold.

1. when i add more modules, you are right the pitch does drop a tiny bit. no big deal. its good to know your psu does this too

BUT

2. when i have my soundlab vco plugged in, but NOT plugged into the speakers, it changes the pitch of other modules on the same psu when its pitch knob is turned...very scary...like a poltergiest.

maybe the problem is just the soundlab vco...i did rip its circuit out of the entire soundlab...i didnt build the whole soundlab, just the vco and i added some bypass caps, but its possible this wasnt really meant to be run as a separate circuit

thanks