Voodoo Lab Overdrive mods and tweaks.

[Cozybuilder]

This shows both series and parallel configurations. One uses a DPDT, one uses a SPDT. If you only use 2 caps as Mark suggested for the series configuration, eliminate C1.

[Plexi]

An update here: placed 2k2 on R5, and now we're talking 

[Plexi]

A bit related question:
http://www.diystompboxes.com/smfforum/index.php?topic=118873.0

[garyg]

I've just built an OD based on the VL overdrive (well, bought a PCB with a bom, not sure if it's the *exact* VL circuit). It sounds pretty great off the bat but was wondering:

1) even at zero gain it's a fairly dirty, I thought the VLOD could do clean boost at that setting, can anyone confirm? Not that I'm really complaining just like to know I didn't screw up anywhere.

2) Maybe this is further proof I don't have great hearing but... I tried messing with the clipping diodes (first time ever...) and struggled to hear a real difference. I can clearly hear a difference between the stock silicons and some schottkys (definitely worth trying) but swapping different LEDs etc... nothing I could really discern. Maybe I need to train my ears a bit?

3) Tone control - anyone added one? I tried hooking a pot and cap across the vol pot as you would in an OCD but it seemed to make zero difference (which threw me, sure even a change in level or something...?)

As I said it sounds great anyway so may just box it and be happy but curious to know if I'm doing something wrong/can't hear for s___.

Thanks.

[Mark Hammer]

I'm a fan of the original Boss OD-1; the precursor to the SD-1.  Unlike the SD-1, it used a fixed treble rolloff in the op-amp stage after the clipping.  The VL circuit uses diodes to ground for clipping, as opposed to the more compressing diodes-in-the-feedback-loop approach of the OD-1/SD-1/TS-9/et al., but you still have the feedback loop if IC1b to tinker with.

As shown, the VL circuit trims back on top end, starting around 4.8khz, at 6db/oct, leaving a some of the fizz intact.  If you either increased the 220pf cap, or used a toggle to add in caps in parallel, you could trim that treble even further, to smooth out the sound.  You can also increase the value of C4, or add in another cap in parallel, since C4 doesn't seem to be removing anything we can actually hear.

[garyg]

Thanks.

I really like how this sounds fundamentally so think I'll keep this one and then build another as a testbed for some experiments (and end up with an OCD... )