Diode volume differences, how to solve??

[Fumi SG]

Hi there,

I finished my first stompbox today (see my other thread). Had some trouble debugging the thing, so it took longer than I'd expected. But I still have a problem. I used two pares of diodes, 2x 1n270's en 2x 1n4148's. I wired them to a switch so I can choose which pare I take. But the 1n270's have a much higher output, and it's a big difference!!

I heard something about adding an extra diode (so then I have 3 1n270's?) and I also heard something about wiring the diodes in serial.

Will this work?? I don't actually have an extra diode, so I prefer wiring them in serial. Or can I do something else??

[bassmeister]

It doesn't feel like I'm the first to suggest this solution, but I haven't seen it elsewhere.

You could use a DPDT switch where one side of the switch selects which diode pairs to be used and the other side switches in and out a trimmer in series with the volume pot. Adjust the trimmer until you can't hear any volume difference when switching between the different diode pairs, then replace the trimmer with the equivalent resistor. One drawback with this solution is that you can only decrease the output of the "1N270 setting" and not increase the "1N4148 setting". It might still be high enough, but maybe the decreased output changes the sound of the overdriven amp in a way you don't like.

[aron]

I would try what bassmeister said. Also try the pedal live; you might decide only one of the diode sets are needed. (asssuming you are going to use it live)

[Fumi SG]

I already used a DPDT switch, and have used both sides. I had to deal with grounding problems, but those are solved now. What I CAN do is leave it the way it is, and use the 'loud' diodes as a solo-boost.

But still, I want to solve this problem!  I already tried resistors like this: diodes -> resistor -> ground... but that doesn't work at all. Anybody??

[WGTP]

Since the clipping threshold of the GE's is lower (I think the 1N270 is a GE), the output of the circuit should be lower when they are switched in.  If it is louder, it appears they are not properly connected, or the switch is backward.  

[Mark Hammer]

I showed how to do it here http://diystompboxes.com/sboxforum/viewtopic.php?t=36496