# Six String Singer Mod



## Travis (Sep 12, 2019)

What do the 68nF C5 ?? Could I Changue It for a 47nf?


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## Travis (Sep 12, 2019)

Could I use the 47nF in C5?? Thanks


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## phi1 (Sep 12, 2019)

It will work, but it may affect the tone (reduce low end). 

If you want to understand what it does, study the mu amp configuration, like the amz mini booster.


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## Chuck D. Bones (Sep 12, 2019)

C5 & R5, along with Q1, form a high-pass filter.  The corner freq is f = 1 / (2 * pi * C5 * R5).  Below that freq, the gain of Q1 / Q2 drops off.  In this case, the corner freq is 2.3Hz.  You could go up to 47nF and not hear the difference.  Same thing goes for C9 & R13.

I'm going out to the driveway now to try and fix my kid's Jaguar.  Pedals are too easy. ?


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## Travis (Sep 12, 2019)

Thank you very much! Now I understand


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## Travis (Sep 18, 2019)

How can I increase the gain?


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## Chuck D. Bones (Sep 18, 2019)

How much more gain?  Do you intend to drive this pedal beyond its clean range?


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## Travis (Sep 20, 2019)

A little bit more of gain, more breakup


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## phi1 (Sep 20, 2019)

i believe reducing R8 and/or R14 will increase the gain. 

Also, where did you get your jfets from and have you measured them? Most through hole j201s you find these days on ebay etc are fake or really out of spec and have lower gain than they should. Since I don’t have a stash of old good through hole jfets, I’ve started using smd with an adapter board (like the one on here).


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## Chuck D. Bones (Sep 21, 2019)

That is correct, reducing R8 and/or R14 will increase the drain current which will increase the gain.  Try going down to 3.3K or 1K.  Do it to one stage at a time, give it a listen and iterate as req'd.  I'd try R14 first.


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## Mike McLane (Dec 14, 2020)

1. The newer version of the Vertex unit has a Rock/Jazz switch (adding the Rock setting) because of user feedback that the unit was too bass-y.  Rather than prevail upon PPCB to make an updated version I'd rather just determine if there are alternate values for my current build as I, too, would like something a bit more "shiny".

2.  How do I test a J201?  What specs/values am I looking for?


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## Chuck D. Bones (Dec 14, 2020)

1. Do you want less bass, or more treble?  The difference is what happens to the mids.  If you know how to use Duncan's Tone Stack Calculator, see if you can get what you want by messing with the tone stack.  If you have a breadboard, breadboard it and mess with C5, C6, C8 and C9.

2. There is plenty of info elsewhere in these forums on how to test JFETs, so I won't repeat it here.  The good news is this circuit is pretty forgiving on JFET specs.  Any Vp should work.  Just make sure your J201s are in spec.  Lotta garbage for sale.


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## HamishR (Dec 14, 2020)

Chuck D. Bones said:


> I'm going out to the driveway now to try and fix my kid's Jaguar.  Pedals are too easy. ?


I'd say give it some water and when it's well enough some meat.


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## Mike McLane (Dec 16, 2020)

Re #2 above, I checked out the JFET test.  Found some stuff on YouTube as well.  We're good.  Re #1, What I'm thinking is to record a guitar raw signal direct into my DAW, then play it back to my FX/amp setup and apply a EQ plugin to shape the sound to what I'm after.  Then make note of what frequency alterations are indicated.


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