From tmoravan@netcom.com Mon Jul 8 15:37:23 1996 8 Jul 96 18:36:23 +0500 8 Jul 96 18:36:09 +0500 Comments: Authenticated sender is 23 Jun 96 10:28:25 +0500 id HAA12199; Sun, 23 Jun 1996 07:22:35 -0700 From: tmoravan@netcom.com (Tom Moravansky) Subject: modding PAIA vocoders Date: Sun, 23 Jun 1996 07:22:35 -0700 (PDT) In a recent post I mentioned that modding the PAIA vocoder improved the sound/functionality. Well, I have been talking to a tech that has done such mods and he agreed to let me post his general notes about what he has found. I hope these tidbits will provide a starting ground for those of you w. PAIA vocoders. ------------------------------------------------------------- From: dean batute Subject: Re: PAIA vocoders After doing listening tests comparing the Paia vocoder to my Korg and Roland units I found that the Paia sounded like it was only 1 or 2 bands. Scoping it told me that there is a huge descrepancy in the gain levels of each of the bandpass filters. As a result you set your input gain as high as you can before distortion but this level is only high enough to trigger the higher gain filters.The lower gain filters never or barely get "activated" To get them to turn on full you'd have to increase the input level beyond clipping. SO!!!! what's the solution??? Put a sine wave signal through the vocoder and scope the outputs of each filter one by one and vary their gains ( by padding the feedback resistor with a trim pot) until they're all equal. Now when you run a HOT signal through the unit, all bands have an equal oppotunity of being activated. Voila... a much better sound. Simple realy :) Hope that all makes sense. If not let me know and I'll pull out the schematic and tell you exactly were to scope and what resistors to pad. Happy Vocoding.......Dean --------------------------------------------------------------- Note: Since I don't have a PAIA vocoder, I didn't want to bother Dean with the specifics. I believe that those of you who have built them can figure out what/where in the circuitry Dean is talking about to add the trim pots. Or, if you're in the Toronto area, give him a shout and he'll do the mod himself for a reasonable fee. -- ___________________________________________________________________________ Tom Moravansky tmoravan@netcom.com