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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...

Since the mid frequencies rely heavily on the corner frequencies of both bass and treble circuits (at least for the "cut"), there is no *easy* way to implement a mid shift on the Beta. It would quickly become a nightmare of switches and dual pots for it to be somewhat effective. An alternative...

Creo que todos hemos pasado por esto ;) I have piled up hundreds of bookmarks related to circuit design, reverse engineering, electronic & audio theory and so forth over the years. Every time I revisit once I stumble upon some info that I hadn't understood or that had gone over my head when I...

Muamp and SRPP are "self-biased", so jfet variation or spread of parameters matters much, much less. Think of the upper jfet as a trimmer that has already done the work for you :)

I find the Peavey Bandit transtube preamp unbeatable when it comes to SS "pedal platforms". No pcb for it (as far as I know) but not too complicated to do either. There is a nice simplified version of it here.

The Catalinbread Sabbra Caddabra was designed specifically to ape the Supergroup + Rangemaster thing. Otherwise, you can tweak the EAE Model Fet to Supergroup specs. IIRC the Iommi setup on the early albums was: Modified Rangemaster (almost full freq boost as opposed to treble) -> Bass channel...