The Amp Garage

Oooops, already spotted an error: C12 should be 3.3nF and not 33nF

This will be for a friend/bandmate. He's currently using a sort of JCM800 2204 that I built for him 5 years ago, except it runs on a pair of cathode biased 6V6, and has a switch to disengage NFB. Turns out... he always plays with the NFB off. With a slightly tweaked tonestack and an OD pedal in fron...

Yup I told him all that and he insisted and bought the amp. Kids. Meh, in my experience, when 100W is too loud, 30W is also too loud anyway. At that point, it's more about weight and cost (acquisition and retubing). After building a bunch of 15-25W Marshall type circuits, I've started going back in...

I would do it like this... http://sluckeyamps.com/phoenix/phoenix.pdf This is perfect! Thanks Sluckey! Its actually very close to what I have now but the values are much different The first Bias resistor I used a 47K where your drawing shows a 220K I also used a 10K pot where yours uses a 50KL I wi...

So, after lots of tweaking, here I am: https://1.bp.blogspot.com/-nrMNpXc0fyE/XrxYKi-5iiI/AAAAAAAALE4/Pn-TyWNT6Z8Ya4EF5bgt2x4alto71B8yACNcBGAsYHQ/s1600/MicroToad%2B2W%2Bv0.6.gif Turns out, good old Marshall values for the tone stack make for great high gain tones. Presence was implemented as a Cut c...

Not sure why everyone is talking about 6L6, as per the original post that is not in the plans. 6V6 only. Cathode biased is of course an option, I actually tend to build everything this way, even when it doesn't make that much sense. Put a big fat bypass cap, bias to less than 85%, and it sounds clos...

I think that (partially) bypassing the cathode of a cathodyne acts to change it into a regular common cathode gain stage at high frequencies, albeit one whose cathode is elevated above 0V. So the (inverting) gain at the anode will be ca 1 at low frequencies and at high freqs - from Aiken http://www...

If i were to attempt this, I would try applying the nfb to the cathode of the gain stage immediately proceeding the PI. That seems to be the most straightforward way to me. Have you checked what the signal looks like on the grids of your output tubes? If you dont have a scope, check the AC voltage....

EDIT: After some research I'm gonna go ahead and build it with what I have, meaning the Marshall 18W OT (Hammond 1750PA) mated to the Fender Deluxe Reverb PT (Hammond 290BX). I see the 18W OTs have been recommended a few times for 6V6 only builds. I know the Brown Note had a stouter PT, but I'm not ...

My cheap advice: Adding more EQ to "too much" will make things worse. Why not lighten the harsh treble boost, instead of trying to compensate later? Because said treble boost is actually more like a low cut (it's not adding treble, it's letting less bass through). Focusing on mids and highs early i...

Nice shredding! Also, this thing is painfully bright No kidding. I see a 470p/470k treble peaker AND a 1000p bright cap prior to the first stage, and another treble peaker prior to second stage. Yikes! Thanks! Yeah I know, but that's pretty common for this type of circuit. Without this the overdriv...

I'm gonna say, as I was wiring this little guy I started having some doubts. So much going on around the channel switch. But it turned out great! No hum, maybe a little more hiss than I'd like. No squealing, even though I forgot the usual small cap from plate to cathode on the 1st stage (common on h...

If the designer is happy (or oblivious) to massively breach the EL34 plate dissipation limit, given a super stiff HT up near 500V and a typical 3k4 OT, it's theoretically possible to get maybe 80W clean out of a pair; so at full squarewave overdriven 120W seems feasible. Point being that the '50W' ...

In trying to make this low power project a bit more aggressive, I was trying to add a little Presence boost. But since it's a cathodyne PI with the negative feedback applied at its input, mixed with the normal signal through resistors, the usual approach doesn't work. But for fun, I tried bypassing ...

Interesting ... 8) By reading Merlin's "pre-amp book", I thought the biasing was more relevant than the tension of the plate, soundwise - as a comment to the use of very high voltages to reproduce the sound of big amps. Maybe someone amongst you guys, could clarify? Maybe so, but it affects the gai...