My parallel distortion box

[ianmgull]

Ben,

I see what you are saying about putting the switching later on in the circuit. I already have the mixer section all wired up in the box so I'm wondering; Would putting the switch after the mixers cap and summing resistor effect anything aside from the current draw of each individual channel? I'm all for being green, I just know I would have to heavily modify the mixer pcb which is already in place.

Hi, are you saying that your switches are already wired, and all of them are hooked up after the summing resistors, on the inverting input of IC1B?  If so, that won't work, as all the effects are connected directly to that point. Turn one off and they would all be off.  The best place for the switch is between the pot and the cap leading to the summing resistor and mixer.  Example, for the clean signal, between pot1 and C11.

Actually they are immediately before each mixers potentiometer. I imagine that is practically the same thing, just switch pot instead of pot switch.

Why so many 2.2megs?

Oh, I just noticed what you meant, there are 5  2.2M pulldown resistors connected to the input jack.  There should only be one, to drain any minute DC leaking back through the input caps.  Actually, Ian, if you haven't made the buffers yet, you can get rid of all of the input components up to the opamps, except for one set (one pulldown, one input cap, two biasing resistors).  Then connect all 5 of the buffer opamps' + inputs together, like orman does with the JFETs in his 4 way  JFET splitter in that link.

Yeah, I see what you're saying with all the pulldowns. As I said above, the redundancy comes from the fact that I made 5 GGG IC buffers for this. I'm considering trying to do a 5 (or 6 realistically) way buffer system with opamps. Unless you guys would recommend the Orman Fet buffers?

[Processaurus]

Ben,

I see what you are saying about putting the switching later on in the circuit. I already have the mixer section all wired up in the box so I'm wondering; Would putting the switch after the mixers cap and summing resistor effect anything aside from the current draw of each individual channel? I'm all for being green, I just know I would have to heavily modify the mixer pcb which is already in place.

Hi, are you saying that your switches are already wired, and all of them are hooked up after the summing resistors, on the inverting input of IC1B?  If so, that won't work, as all the effects are connected directly to that point. Turn one off and they would all be off.  The best place for the switch is between the pot and the cap leading to the summing resistor and mixer.  Example, for the clean signal, between pot1 and C11.

Actually they are immediately before each mixers potentiometer. I imagine that is practically the same thing, just switch pot instead of pot switch.

Oh, that works fine.  Not to be redundant, but you want to ground the mixer side with the switch rather than ground the effect output and leave the mixer floating.  So the top of each volume pot  goes to the common, the effect output to one lug, and ground to the other.

Your opamp buffers are fine!  Go for it.

[ianmgull]

I see what you're saying now. I just need to reverse two of the poles on the switch.

[Sir_Ian]

Heres my two cents.

I was looking at it all and I was thinking......I don't know if you need all of those buffers. For instance, the tube screamer schematic already has good input and output buffers. So if you put an input buffer before the tube screamer you would really be sending the signal to through two buffers. I guess it would still work and all, but you commented on how you were tight on space, so maybe getting rid of the GGG opamp buffer might save some room. I guess you could just leave the input buffer off the tubescreamer when you build it, but  I'd find it easier to use a layout for the tubescreamer with the input buffer already on it and get rid of the other one. (not to mention, it'd be more "authentic".)

Who knows, I might be wrong for whatever reason. I'm new to this. So if I am wrong, why would he want the other buffer? I'd like to learn what I'm thinking wrong. If I am right, I guess I'd just suggest looking at each of your circuits and see whether you would have redundant input buffers.

[ianmgull]

You may be right as far as I know. It was my understanding however that the buffers had to be identical so one didn't load the signal more than the others because of impedance mismatches.

[ianmgull]

I'm not dead yet!!!!   I seem to work on this project in bursts, a couple manic days here and there, then it's forgotten for a month...