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A part of me is disappointed by the plexi schem (one single clipping stage, and with 1N914, really?). A part of me yaps about the importance of voicing over clipping devices, and somerhingsomething learning how to use inverting stages in such an elegant and simple fashion. But then a part of me...

Personally I wouldn't touch that pcb. If you REALLY insist, replace R4 or R8 with a c10k pot for a presence control.

Oooh, I see what you did now with the freq pot. I can't f**** visualise things without spicing them... I might indeed lower R12 to 100k for a broader Q, and change C6, C8 to 2.7nf & skip the switch - I don't think I'll ever want to boost under 400hz or above 3k. I did find a ganged B20K among my...

Awesome, can't wait to hear that! One thing to consider - if we max the tone controls, the opamp's gonna clip due to the amplitude coming from the last bjt. It'd be better to stick e.g. a 68k-33k voltage divider before the buffer to make sure not to hit the rails at the EQ...

That's a beaut'!!! I really need to breadboard this one when I'm done with my current preamp (or when I scrap the whole thing in frustration, 50/50 odds...). I will have to scale up values, since I only have C100K ganged. I've been wanting to do the perfect 80's boost with a compressor into a...

Check the GK Rails - might be exactly what you need. SS poweramp grit that gets growly and throaty if needed. Circuit info here.

The AMT P2 gets really, really close, but I don't know if there is a pcb for it anywhere. Otherwise, the Baja EVH and its subsequent version by dylan are quite nice too, a tad undergained though, compared to the original amp.

THIS. The frequency response of the Metal Zone is extremely similar to that of the VH140. I've been procrastinating on adjusting the VH140 to exact Metal Zone frequency specs and adding the tone stack from the GK 250ML after it for a good three years now (I'll get to it, I swear!), but it's...

I wasn't aware of this pedal actually, thanks! This looks familiar... Yamaha G100-II:

What's the deal with the 100k resistors to V+ at muamp output on the XTS Atomic (Nucleus Overdrive)? Referring to R12, R15, R37 on PPCB schem. From what I see, all they do is lower the gain a tad, due to load, and keep the drain of the lower jfet at a voltage ever so slightly higher than the...

It's nice that the compressor looks quite simpler than on Rockman circuits. do you have to do any matching on it, or the average mmbfj201 will work ok? I don't think I've seen a scholz-comp circuit without trimmers or hand-picking jfets before.

In this particular circuit, they tame the high end a liiiiiiittle bit, not perceptibly as temol has shown. Also, they are probably there to tame possible high end oscillation around the opamp, which is good practice in high gain applications. Bear in mind that, in feedback loops among others...

I don't think there's gonna be any perceptible change subbing those caps with either value. This is essentially an ever so slightly tweaked Boss Metalzone, by the way ;)

Any resistor in series with the signal followed by another resistor to ground forms a voltage divider, however small. In this particular case you cut roughly 10% of the signal that comes out of IC2B, in addition to providing a slightly different taper to the left half of the gain pot, which also...

Funny that you should use gyrators for the EQ - I have been working on a similar arrangement (volume on inverting opamp + gyrator mid control) on a JMP1-based dirtbox, after being disappointed by the bax tonestack in that setting. Indeed the Friedman similarity is apparent, to the point of...

Using original schem refdes: - You don't really need R26, R27 and C23. - I would keep R14 as it forms a voltage divider with R12. - You could probably skip the last opamp and take the signal out after the vol pot. That last stage is just mixing channels and its corner freq is practically...

It is considered good practice to have first and last stages on separate dual opamps, especially when huge gain increases are present (or so I have read in multiple sources). In my very limited experience, I have only had issues if/when overgained signal is entering the last section, or if that...

2sk117 are used as buffers, so absolutely nothing special about them :) I tossed in j201 in my Baja builds back then because that's all I had. Use any small signal jfet, or even replace them with opamp buffers, it won't make a difference at all sound-wise.

Leg 2 of LoCut should go to VREF and not to ground. Although I suspect that this is only part of the issue, your Vref voltage is too high to be caused by this accidental ground connection. Double check that you have 1/2 V+ between R16 and R17, and track from there.

I'd be tempted to adscribe to Cybercow's answer, however, I kinda feel there's a catch somewhere in the question. IME it is possible to get a JFet to exhibit the same gain as a BJT just by adjusting the components values around it, but the downside is loss of headroom. Haven't tinkered enough...