Diode switching for Fuzz

[PMowdes]

I've seen a few things on here where people mention putting different diodes on a switch to get different sounds out of a fuzz.

I have a green Russian big muff and a bunch of different diodes that I want to try, would anyone care to talk me through how it's done?  

Thanks in advance

[Ciaran Haslett]

The diodes are arranged in anti-parallel (same as parallel but one anode is opposite the other) on the BMP.  If you want to put different diodes on a switch you could...(using a DPDT switch)

Remove the diodes from the layout
Wire lug 2 to one side where the diodes used to be
Wire lug 5 to the other side
Solder an anti-parallel pair to lugs 1 and 4
Solder an anti-parallel pair to lugs 3 and 6

Repeat for the second gain stage.  It doesn't matter what way the diodes are positioned as long as they are arranged as above.

Using a 4PDT switch would allow you to switch all diodes at the same time.

Good luck

[PMowdes]

Ciaran Haslett wrote

The diodes are arranged in anti-parallel (same as parallel but one anode is opposite the other) on the BMP.  If you want to put different diodes on a switch you could...(using a DPDT switch)

Remove the diodes from the layout
Wire lug 2 to one side where the diodes used to be
Wire lug 5 to the other side
Solder an anti-parallel pair to lugs 1 and 4
Solder an anti-parallel pair to lugs 3 and 6

Repeat for the second gain stage.  It doesn't matter what way the diodes are positioned as long as they are arranged as above.

Using a 4PDT switch would allow you to switch all diodes at the same time.

Good luck

Thanks man,

Does that mean for a 4pdt switch the diodes go across 1&4, 3&6, 7&10, 9&12.  And the two in/out goes across 2&5 and 8&11????

Cheers

[Ciaran Haslett]

That's right yeah.  As if it were 2 DPDT switches in one.

[heuermh]

These little guys are great for diode switching (currently out of stock though)

http://www.guitarpcb.com/apps/webstore/products/show/3186804

[vid.sicious]

I've used this on a 2 pole 3 position rotary switch for my Proco Rat diode clipping selection. The top LED is mounted externally so if you don't need that, you can just wire up the LEDs back to back, just like the diodes. Lugs 7 and 8 are empty for 'Diode Lift' mode which bypasses diode clipping. I tried putting a connection between them first but it cut out the signal entirely (I believe it was sending all the signal to ground). You can get switches with more positions to have even more options!
And I didn't mention in the diagram but if you do it this way, you probably should replace both diodes of a clipping stage. For my proco rat I've added 2 rotary switches replacing the one diode clipping stage on the circuit: one shown above and another one with Ge diodes and green LEDs.