Voodoo Lab Sparkle Drive - tone suggestions

[jhaneyzz]

I just finished a nice build of a Voodoo Lab Sparkle Drive pedal. I am actually using it to add some grind to my acoustic guitars. The ability to mix the clean channel with the distorted channel makes this an ideal pedal for my application.

The problem I am having is that the tone pot only controls the tone for the drive channel. If I have modified the tone at all, then the tone varies progressively when I adjust the channel blend.

Ideally, I am looking for a way to add a similar tone control to the clean channel.

For reference, here is a link to the component layout I used, from tagboardeffects.

http://tagboardeffects.blogspot.com

James

[GGBB]

Can you post a link to a schematic? Component layouts are far less helpful for suggesting modifications to a circuit than an actual schematic. Plus, your link is just to the home page which changes frequently - there's no Sparkle Drive layout on that page right now.

[jhaneyzz]

You make a very good point.

I am having a difficult time finding a schematic that matches, component for component to my build, but the image linked here (found on this site) seems pretty close.

[antonis]

Copy/paste C4, RV2, R3, R12, C5, Q1, R9 between U1A output and C7..
(IMHO, R8 is optional here..)

Use a dual gang pot for RV2 if you want simultaneus tone adjustment..

[jhaneyzz]

Thanks,

Kind of obvious actually. 

I'll experiment with synchronizing/splitting the tone controls. I think I might find that the tone controls need to be tweaked individually between the clean and drive channels as the gain in the drive channel tends to modify the tone which I assume is causing the effect I am trying to control in the first place.

[marcelomd]

What happens if you move the tone control after the blend control, before volume?

[Mark Hammer]

The existng tone control effectively removes fizz and sizzle from the crunchy side, which is what the lion's share of overdrive tone controls normally do.  With the drive near minimum, to avoid clipping, and the "clean" control set entirely to the crunch side/path the existing tone control would let you dial in a muted tone from that side.

So what could we do with the other channel/side that could be helpful?  One way is to take a clue from G&L and Reverend guitars and incorporate a "Bass Contour" control on the clean side.

The schematic of the Sprinkle DRive shows a 10uf cap going to the "clean" side of the mix/blend control.  Make that 10uf cap go through a 50k-100k variable resistance before hitting the outside lug of the mix/blend pot.  Then, straddle the 10uf cap and added pot with a smaller-value cap (let's say 47-100nf).  That cap allows upper mids and treble from the clean signal to pass through to the mix/blend pot unaffected. Lower mids and bass, meanwhile have to pass through the 10uf cap and added variable resistance to reach the same  point.  This allows you to dial in as much or as little of the bass in the original clean signal as you want to.