How can I get an even volume with a switch between clip diodes on a od/dist ped

[signalpaths]

I want to put a switch in one of my old junky od/dist pedals to add and subtract different diode clipping sections located on a small separate board.  The problem is there is a very large difference in volume between Ge, Si and the power diodes I am using.  Can I use a resistor or pot to set the volume of a particular section? 

Thanks

Eric

[foxfire]

well you could use a 3pdt switch. 2 poles would be used for the 2 volume pots and, the third pole would switch the diodes. Dragonfly has a diagram for switching between pots in his gallery using a 2pdt switch. so you would just use third pole for switching between your diodes.

[joegagan]

i have had good results using a dpdt switch. one side switches your diodes, the other changes the gain of one of the trannies usually at the R emiitter to ground. takes a little experimenting to find the balance of volume, but it does work.

[Mark Hammer]

Another approach is to use the toggle to enable/shunt a fixed resistor in series with the input of the volume pot.  For instance, if you had a 50k volume pot, a 10k resistor in series with the input would make the pot behave like a 60k pot that can never be up more than 5/6ths.

I did this with a tube sound fuzz I made a number of years ago ( http://hammer.ampage.org/files/tsf-pix.jpg ), the idea was that I would use a switch to simultaneously increase the drive of an op-amp stage feeding the clipping section, AND turn down the volume level to compensate for the increased drive and resulting level increase.  The intent was to achieve more "hair" on the tone, but with no discernible volume shift.

For the most part, it worked well and I can imagine that a similar strategy could be deployed to simultaneously select diode complements and compensate for their respective levels.  Note that if you add a series resistor to the input of the volume pot, shunting (bypassing it with a straight wire) it will result in a volume increase, and lifting the shunt will drop the volume.  So, if you were switching between, say, silicon and germanium diodes, you would want to enable the shunt for germanium (because they have a lower output level and need the volumeboost), and lift the shunt for silicon (because they will have a hotter output level and need to be padded down to be equivalent in volume with germanium).

[signalpaths]

Thank You Mark, Joe and Foxfire.  Your input is greatly appreciated.

Eric T