Bass: Voodoo Labs Sparkle Drive

[seanm]

I love the Sparkle Drive, but I found it just a little on on the mild side. (Take a walk on the mild side!).

So I finally upped C4 to 100nf. C4 is the  47nF cap that goes to ground via a 4.7k resistor in the clipping stage. This lowers the clipping about an octave to make it more in the bass range.

This gives me more OD without being over the top. I can still get a very mild OD. It is now closer to the Fulltone Bassdrive, but not as aggressive as the Bassdrive can get. If I want more fuzz, I can use a Big Muff.

I might add an switch to go from 47nF for guitar to 100nf for Bass .... or I might not

[Gabriel Simoes]

could you tell me where you found this schematic ?

[seanm]

could you tell me where you found this schematic ?

Yup, I found it here: http://home.hetnet.nl/~chrisdus/download/VLSD.jpg

It is basically a tube screamer with a clean blend. But I love how the clean blend works. In fact, I liked it so much I bought the pedal!

[Basstyra]

I have difficulties to understand how the optocoupler works....  :shock:
Seems to be efficient, anyway, as a bypass !

Do you know other pedals where this is used ?

[Gabriel Simoes]

I think the optocoupler works like a protection circuit against reverse polarity, isn't it ?
I think you can go without it .... and use the common true bypass scheme ...
For bass use, isn't there any other mod to be made ?
I just didnt get that clean pot, the position ... what does that mean ?
and in the voltage divider, that 2 "broken" lines , with a 4 on one side and an 8 in the other , what does that mean ?
Thanks
Gabriel

[The Tone God]

I think the optocoupler works like a protection circuit against reverse polarity, isn't it ?

Nope. The optocoupler is switching the input signal similar to a SPST switch. Its a cheap/lazy way to add another pole to the footswitch without having to use a 3PDT. It would not be considered true bypass though but close.

I think you can go without it .... and use the common true bypass scheme ...

Yep. In that case it would be true bypass.

I just didnt get that clean pot, the position ... what does that mean ?

It is a dual gang pot meaning two pots controlled with one shaft.

and in the voltage divider, that 2 "broken" lines , with a 4 on one side and an 8 in the other , what does that mean ?

The 4 and 8 are the pin connections on the ICs for power. 4 is ground and 8 is V+.

Andrew

[seanm]

I think the optocoupler works like a protection circuit against reverse polarity, isn't it ?
I think you can go without it .... and use the common true bypass scheme ...
For bass use, isn't there any other mod to be made ?
I just didnt get that clean pot, the position ... what does that mean ?
and in the voltage divider, that 2 "broken" lines , with a 4 on one side and an 8 in the other , what does that mean ?
Thanks
Gabriel

When I breadboarded the Sparkle Drive, I ignored the optocoupler.

There are tons of mods that can be made, but  I like it the way it is. I just wanted a bit more grit but not too much. I *have* pedals for too much
But it is basically as tube screamer. Tube screamer mods will work.

The clean pot is a dual ganged pot with a clean side (top) and dirty side (bottom). As you turn up the clean, you reduce the dirty. This means you can turn the clean knob without changing (or with minimal changes to) the output volume. Very cool design IMHO.

I think the 4/8s are probably test points. I ignored them too

[Gabriel Simoes]

What kind of pot is that ?? dual ganged ? have never heard about them, maybe not in english hehehe
how do they look ? what are they specs
As i see, the input and output caps are big enougth for bass use, so I will try the mod that was proposed (change c4 for 100nf) and plug my bass to see if it works ...
I do have to design a layout for doing the pcb ... have anyone built it with perfboard ?

So the optocoupler is used to like a big enougth r, so no sound would pass to the circuit and it would act like ground to the clean sign ? i dont get how it works, but since its kinda hard to find the h11f3 here in Brazil I will use the dpdt and true bypass with the millenium circuit .... but if anyone could explain in to me I would get really happy (isnt to learn what its all about ?)
Thanks
Gabriel

[seanm]

The 4 and 8 are the pin connections on the ICs for power. 4 is ground and 8 is V+.

Duh  :oops: I just hooked the pins up without thinking about it.

[puretube]

dual ganged pot: aka "stereo pot"... (aka: "tandem pot").

[gaussmarkov]

hey sean,

it's great to hear that you are still experimenting with blends.  now that you have breadboarded the sparkle drive, have you thought about putting the dual-ganged pot arrangement into your b.blender?

cheers, paul

[Gabriel Simoes]

What software should I use to make the sparkle drive pcb

And .... any other mod for using it with bass ?

[seanm]

hey sean,

it's great to hear that you are still experimenting with blends.  now that you have breadboarded the sparkle drive, have you thought about putting the dual-ganged pot arrangement into your b.blender?

cheers, paul

Not really, since the b. blender seems to work well with the simple pot. Dual ganged pots are harder to find.

I did try to add the dual pot idea to a big muff, but I haven't found an arrangement I really like yet.

[MartyMart]

hey sean,

it's great to hear that you are still experimenting with blends.  now that you have breadboarded the sparkle drive, have you thought about putting the dual-ganged pot arrangement into your b.blender?

cheers, paul

Not really, since the b. blender seems to work well with the simple pot. Dual ganged pots are harder to find.

I did try to add the dual pot idea to a big muff, but I haven't found an arrangement I really like yet.

I just used a 500k dual gang in WGTP's "distron thrust" - quite nice to
blend in the clean gtr as the pot is turned up, I have it letting through
clean as there is more distortion..... seems to work well and doesn't
cause any "phase" problems that I can tell.
It sounds like a "layered" clean/crunch tone ... nice

Marty.

[Gabriel Simoes]

Let me see if I got it...
So, this is a dual ganged pot ?

http://www.feratelin.com.br/loja/produtos.asp?produto=1489

Thanks =)

[puretube]

 yes:, a duplo... ( x2)

[Gabriel Simoes]

a linear one here, generic of course, but since we cannot find good pots in brazil thats the one we use, costs less than 1 dollar =)

[RLBJR65]

Gabriel Simoes Posted:

Let me see if I got it...
So, this is a dual ganged pot ?

http://www.feratelin.com.br/loja/produtos.asp?produto=1489

Thanks =)

Yes :wink:

[seanm]

Let me see if I got it...
So, this is a dual ganged pot ?

http://www.feratelin.com.br/loja/produtos.asp?produto=1489

Thanks =)

You got it