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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...

So f*n cool, mate! Nice to hear it played by someone else than me :) I also tend to get whining from the breadboard withthis kind of circuits, I usually rejig some of the gain stages further apart til it stops. the resistor + cap after the Hi cut control is there to counter the treble bump from...

Sure, temol ;) At drain of last gain stage: After hi cut control: Nothing too outrageous, kinda standard-ish JCM but with more gain. Trying to ape 90's King Diamond type of tone, a bit more modern than 90's standard HM, but not quite modern sounding by today's standards, not scooped nor...

I did some sims just to compare side to side, here's some observations. We have those three circuits, left to right: - First one is a fairly standard jfet gain stage, with "cathode follower". - Second one is the same, but with a follower nicked from AMT L2 pedals (those that have it, e.g. S2...

Do you mean the whole bootstrapped follower thing? I have never seen it in any pedal design, personally. There is an old thread on DIYSB about a similar idea using bjt, but I don't recall seeing it in any "complete" circuit. I've ltspiced it with fets, it does increase gain and it does exhibit a...

I'm not knowledgeable enough on mosfets, but the ubiquitous RG Keen certainly is: http://www.geofex.com/article_folders/mosboost/mosboost.htm

Cool design!! This amp has an intereating topology. Kinda like the non-interactiveness of the treble control, although the mids don't seem to do heaps. I wonder which stage clips first, 6AN8, cathodyne PI or power stage, and which one is responsible for the sound characteristics?

I tend to use jfets with tight specs (SMD J201, 2N5484, J113, 2SK208R, and the dmos LND150), and rarely bother checking their Vp or IDSS. By simulating on Ltspice, you can start with drain and source values that are in the ballpark, then check with the multimeter and do some small adjustments to...

Personally, for jfet stages, I focus on 3 things: - Bias point (asymmetry) - Clipping point (gain) - Source capacitor if present (freq response) When converting from 9 to 18v (or more), leaving all source components the same and just changing the drain resistor to bias the jfet will get you in...

Never tried higher voltages, too much faff. As drew points out, 18-24v sounds great :) And yes, 9v was initially done to keep the same "standard voltages" for 99.9% of pedals. Incidentally, J201s are one of the few jfets that sound great at 9v. 2SK208 (as seen in AMT circuits) also sound really...

I've breadboarded quite a few jfet circuits at 18v and 24v. JFet, BJT and Depletion Mosfet will all exhibit cathode follower compression/distortion, with some difference in regards to the tone/timbre. I found LND150 to sound a bit darker (or less harsh) than Jfet, with BJT being a nice middle...

There goes. I find that biasing LND150 with a diode gives a bit more snarl than resistor+cap, but ever so slightly lower gain. I didn't emulate the feedback around the valve stage because it would have defeated the mosfet grind I was getting :D "cathode follower" can be anything you fancy, bjt...

Note that, in the Sabbra snipped you posted, you can replace the fixed tonestack with actual pots for more versatility ;)

The original Laney presence control relies on modifying the frequency response around the feedback loop between the phase inverter and the power amp stage (essentially allowing more/less high frequencies to feedback). In your schem, and the EffectsLayouts project, the phase inverter is...

Funny, I breadboarded that channel two weeks ago, with LND150 in lieu of tubes, and the (heavily modified) diode section of the Ethos twe-1 instead of leds. Quite nice sounding actually, I can post a schem if interested. I used TL062 for opamps (a tad less harsh than 72s or 4558s), ran the whole...

Not the best practice IIRC, but depending on the circuit you might get away with it. Would that be the Randall X2-G3 or similar?