Build Your Own Clone Message Board

I'm trying to implement the chorus mix mod posted in this thread (and others) viewtopic.php?f=18&t=25674&p=248394&hilit=chorus+mix+mod#p248394
I'm very sure I have it wired correctly, but I get no sound in chorus mode and it's OK bypassed. If I remove the mod and use just the resistors it works fine. Adjusting the trim pot makes a small noise at the ends of its travel with the mod in place. Has anyone done this mod and had it work OK? I'm sure I must be missing something. Thanks!
Dave

Yeah, it's been implemented successfully. Can you post pics of your mOD so we can see the connections?

I added an Alpha 16mm pot below the LED and under the board. I staked the resistors with silicone to prevent movement or contact with the board or ground. I don't measure anything contacting ground other than the center lug of the Mix pot. Hopefully the pix will show you something. Thanks!
Dave

VERY nice implementation of the mod! Those carbon film resistors - are they 10k? I see green and orange bands, which makes me think they are another value.

http://www.buildyourownclone.com/pearl_chorus.pdf

Here's the schematic for the Pearl Chorus. It's where I first encountered the idea of a passive blend circuit of this type. It works very well for modulation effects that have a wet/dry mix. This is where I got the "blue print" for the blend portion of the circuit in the BYOC phaser and compressor.

Anyhow....You can see that the Pearl and the CE-2 are very very similar. And as far as this mod is concerned, the two might as well be clones. The only thing I could suggest doing differently is adding two caps. One at the beginning of the wet signal and one at the beginning of the dry signal, just before they meet up at the mix pot.

Morgan, Thanks! Yes they are 10K resistors. I've found a strange phenomenon. If I unground the input and output jacks it works. As soon as the jacks touch the case it goes dead, and I'm talking about the sleeve that is supposed to be grounded.
byoc, do you think adding the caps has any bearing on this weird grounding issue? I'm going to try ungrounding the Mix pot from its case and grounding it to some other places in the circuit.
Thanks for all the help!
Dave

Wow - weird! There are similar blend circuits where the wiper of the mix pot is referenced to other things besides ground. The 5k comp has the wiper referenced to Vref, and I think I've seen it referenced to V+ in another circuit. So, you might also try taking the wiper of the mix pot over to Vref or V+; but you'll def need to add coupling caps for that to keep stray DC out of other parts of the circuit.

Here's the comp schematic:

Well, I added caps to both the "in" and "out" of the 10K pot one at a time essentially isolating the signals from a direct path to gound. The dead pedal syndrome was corrected, but the Mix pot did very little. So I re-installed R20 (47K) and used a pot in series with R19 (33K) for my Mix control. The taper isn't right, but it works well. I'm still not sure why the first mod doesn't work for me, but the second one does so I'm happy. I'm trying out different opamps now. It sounds really good. I had made a couple of changes to increase the Depth and Speed a bit. I added a shielded input wire to the foot switch to eliminate the ticking. Works great now. Thanks for all the input.
Dave

Good deal. One of the Boss choruses with a mix mod actually used a C250K pot for the mix on the wet level resistor. It works well. You can check it out in Tonepad's documentation on their version.