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Circuitbenders Forum => Circuitbending discussion => Synths & Samplers => Topic started by: plasticanimal on June 22, 2012, 07:29:56 AM

Title: Need help with POLY 61 mod
Post by: plasticanimal on June 22, 2012, 07:29:56 AM
I'm trying to add a OSC balance pot on the first voice to use in monophonic mode. I got it to work but in poly mode that voice is noticeably quieter than the other five. I used a 10k dual gang pot before the caps and resistors on each OSC path just before they meet. Should I use a different value pot or do I need to do something else?
Title: Re: Need help with POLY 61 mod
Post by: Gordonjcp on June 22, 2012, 09:44:49 AM
You'd need some sort of amplifier to compensate for the loss through the pot.
Title: Re: Need help with POLY 61 mod
Post by: plasticanimal on June 22, 2012, 05:17:47 PM
Ah, OK. Thanks for the help. Seems like it may not be worth the effort now. Hm, anybody know of a way I could multiply the parameter over six voices without having six separate pots? Maybe use vactrols?
Title: Re: Need help with POLY 61 mod
Post by: Gordonjcp on June 22, 2012, 10:39:23 PM
Sounds like you'd need to build some VCAs.  If you look in the service manual for the Poly 61, you'll see there are two VCAs used in each voice - one for resonance, one for final VCA - consisting of two transistors and a couple of resistors.
Title: Re: Need help with POLY 61 mod
Post by: plasticanimal on June 25, 2012, 07:35:12 PM
I see what you're saying. I've never built anything like that but I'll give it a try and see how that goes. I'll probably try a filter in mod while I'm at it. Thanks for the help Gordon.