Liquid Sunshine Layout----have a look? MARTY!!!!

[cbriere]

i understand, we don"t want to COPY the Subdecay pedal,
but,
this schematics is a good start for a concept to do overdrive
with classA circuitery. I will play with this prototype a bit to
see if any tweeky can ake it suit my taste. 

cb

[MartyMart]

i understand, we don"t want to COPY the Subdecay pedal,
but,
this schematics is a good start for a concept to do overdrive
with classA circuitery. I will play with this prototype a bit to
see if any tweeky can ake it suit my taste. 

cb

See my list of "tweaks" within this thread, mine is sounding great now

MM.

[markm]

The real problem lies in that the two Drive pots do not inreact with each other.
The one on the bottom of the layout is utterly useless for the most part.
That would be a good place to start 

[Brian Marshall]

I havent been able to hang out here much lately.  The circuit of the liquid sunshine really has not changed much.  This schematic is really poorly drawn, but other than Jfet changes this is what I was building up until late early 2006.

The first 30 units or so used MPF102's, but they were from a special batch I had sitting arround, and i have not seen MPF102's with the same specs since.  I highly recomend not using MPF102's.  2N5457's can work, but you have to go through about 20 of them to find one that will work.  Essentially the trim pots should bias the jfets at about 25k.  anywhere from 20k to 30k should work, and have enough gain.  I have been using 2n5458's in the liquid sunshine with good luck for quite a while.  Some batches I get in, all of the fets work... Even still, I keep a liquid sunshine breadboarded, and check each fet by ear.  Some of them I just dont like the way they sound, others dont have enough gain... so i end up using them as Q1 for the buffer.

The 100k resistor in series with the output pot was changed a few months ago to 10k, and the cap to ground is now 10nF.

The first pot that is unmarked should be B100k.  If you want to substitute another value go smaller not larger, or the positive feedback will cause oscillation.

There are all kinds of things that can go wrong in this circuit if your not careful.  Eliminating the positive feedback loop is the easiest way to get rid of it.  Layout can cause problems as well.

Using Jfets with anymore gain than a typical 2n5458 will probably result in muddy tones if not splattery.  I had some good luck with j201, and j113's after reducing the source resistors on q2 and q3 to 2k 

Either way I'd higly recomend socketing Q2 and Q3.

hope that helps

B