The Amp Garage

This NE555-based SMPS circuit has been around for quite some time. You can get a PCB from these folks and put one together, then breadboard your pedal circuit. It includes a 6V regulated supply for heaters, and it will operate on 12V for increased B+. https://frogpedals.com/index.php/product-categor...

Did you settle on a 'magic' hFE for the Q1 & Q2? I have built the Fuller model (other as well), it's nice to have the contour and bias knob in addition to the vol and fuzz. It's that rolled of vol on guitar that killer. For the Fuzz Face I built I followed recommendations from RG and Small Bear, hf...

I have played with that tester and mentioned (somewhere) previously that it can measure leakage current on Ge transistors. It's a handy little gadget in general. Never compared directly with RG's method, so it's nice to hear that they agree. edit: did you find that the leakage-corrected hfe using th...

Matt J wrote: ↑Mon Apr 29, 2024 1:55 am ...should I leave the PI cathode at 470r as on the original 2nd Gen circuits or switch to a 820r PI cathode seen later amps with a full presence control and 12AX7 PI tube?

I'd say for 12AT7 keep the 470R bias resistor.

Quick clarification: I went with the 3 position R/J switch for the PAB center. Is there any modification I need to make there or at the rear panel relay switches for this to work either with the footswitch or without? Dumble did not always wire the Manual PAB switch lugs on the back panel (see #102...

ynor wrote: ↑Sun Apr 28, 2024 3:38 pmI would appreciate if you could check if my voltage readings are as they should be (quality check :)

BTW, with 35 mV on the cathodes your bias is pretty cool at 0.035A X 432V = 15.1W, or just over 50% of max anode dissipation (30W). You could bring that up to 60%, around 42 mV.

ynor wrote: ↑Sun Apr 28, 2024 5:11 pmWonder if the filaments wiring are too close to the board on the left, and if that's what's causing the last remnants of hum?

I doubt it. They are twisted, and that side of the filter board is not sensitive. I suppose you could run the heater leads around the other side of the PT if you want to.

It's possible that the magnetic field from the choke was inducing current in the OT, as it receives a pretty noisy DC voltage with a sawtooth waveform on it, or maybe more likely that the original OT was not doing a very good job of cancelling the AC on the B+1 feeding into the primary center tap. T...

I don't think temperature rating necessarily means anything in isolation, it's not a hard limit. It's that temperature at a specific ripple current and voltage for a certain amount of time. An 85c cap with otherwise better specs will probably outlast the 105c cap at 105c. No idea how much you need ...

These amps are the tools of his trade. They are also his pension pot. Yes, and if he uses them in his work he can write them off as capital investments and depreciate their value for tax purposes. I found it. Check out 1:08:10 to 1:11:08 Thanks, pretty much as you said, but he has to be aware that ...

In a recent YouTube clip he essentially said that if you’re mad that he bought a dumble amp, then the next time one’s up for sale go ahead and buy it. JB just dropped a notch in my estimation. Why? I think he truly appreciates the gear he has. I could be wrong… Got a link to that YouTube? I realize...

You will not regret investing $120 in a Weller WE1010NA or Hakko FX888D-29BY soldering station.

I’ve never opened one up, but it looks like the brass screw is a worm drive gear. In this case it’s very compact and makes the adjustment easy to access.

UJust to be sure; I’m using the “Separate Masters HRM, Bluesmaster” connections, correct? Correct. One of these 25-turn Bourns trimmers https://www.mouser.com/ProductDetail/Bourns/PV36X504C01B00?qs=ifmdR88tEJ9yfzS1pF2%2Fqg%3D%3D soldered to your PAB relay board would work for the variable lift. Ben...

HAD used different relay PCB's for the OD and PAB, which seems silly when a generic board can be used for either. The connections in the boards .pdf use the universal relay PCB shown there, or you can use the C/NC/NO references to use any other DPDT relay board.