The "Poor Mans" SparkleDrive!

[dachshund]

I recently built the Sparkle drive, so I'm curious: is the Srinkle designed to avoid using a dual-ganged pot?

[Mark Hammer]

Not so much "avoid" as "not require".  Many people tend to find less local choice in dual-ganged pots (if there is any choice at all), so folks tend to design in a manner that doesn't require them.

But you're right, though.  It would be possible to design a comparable circuit where there are counteracting volume controls for each channel.  Just keep in mind that pots containing a log and antilog resistive element (eseentially what you'd need for a dual level-mixing control) are very hard to find.

[markm]

I recently built the Sparkle drive, so I'm curious: is the Srinkle designed to avoid using a dual-ganged pot?

The word from gm is that the schem for the SparkleDrive has errors.....any problems with your build?

[dachshund]

Not that I noticed - nothing obvious. This is the schmatic I used: http://home.hetnet.nl/~chrisdus/download/VLSD.jpg
Actually, I saw another version that didn't tie the 4.5V reference to the spot where the ganged pots are connected. The schematic I used has this connection, the other did not. Maybe that makes a difference, it would leave an opamp not biased correctly. ??

[Rob Strand]

Markm, thanks for the Qudos.

The sparkle drive was designed with a single gang pot in mind.   The circuit was made a minimal as possible.  The only thing I had to trade off/juggle was the amount of clean boost in full clean mode.

You can use a different taper pot to change where the balance point is in the centre of the blend adjustment (if you need a reverse log you can use an easire to get log in reverse provided you accept the clean/distortion direction is reversed - no big deal).

[markm]

I have to say Rob, my hat's off to you!
This circuit does sound fabulous in it's original form and has all sorts of possibilities for the tweakers too!
I would imagine the clean channel could be incorporated into some other effects such as a comp or fuzz with tremendous results!
Build this thing.....it's worth it!

[WGTP]

Using Rob's schematic, ad a notch filter after the clipping diodes, make the "clean" op amp a TS type circuit, rolling off the lows and highs so that the mids are opposite the notch in the other section, and you have something very simliar to the Boss OS-2 Overdrive/Distortion.   

[markm]

Using Rob's schematic, ad a notch filter after the clipping diodes, make the "clean" op amp a TS type circuit, rolling off the lows and highs so that the mids are opposite the notch in the other section, and you have something very simliar to the Boss OS-2 Overdrive/Distortion.  

Interesting! 

[WGTP]

http://aronnelson.com/gallery/WGTP/Boss_OS_2_Mods?full=1

Really, it is more of a Rat/SD-1 combo.   

[evertonberger]

Hi I've built this babe and I've been using this circuit with my jazz bass now... the mods i've made are the same of the TS fat and this rocks!!!!

[markm]

Nice!
I'm extremely excited about this particular circuit.
It's seems as though it a "sleeper" in the DIY community and really deserves some attention.
Thanks for the support! 

[WGTP]

I was talking to my son about the OS-2 and he discribed the blend effect as going from '80's mid-rangey to '90's notched mid.  I'm not real keen on mixing in clean signal, but the circuit is appealing in that the "clean" path can be made into a number of things to "mix" with the distortion path.   

[markm]

I'm not real keen on mixing in clean signal, but the circuit is appealing in that the "clean" path can be made into a number of things to "mix" with the distortion path.  

Absolutely.
I think there is alot of "tweak" and mod potential here although, even in stock form, I like it!