The Amp Garage

Meanwhile at the US Trademark Trial and Appeal Board... Petitioner Request to Withdraw as Attorney Namely, the client has become unresponsive and further does not appear to be paying for continued services of the undersigned. (2) the client has been notiied of the undersigned’s desire to withdraw f...

10-K seems a doubtful proper value. I've seen 100 ohms up to 2-K on screens, depending on amp model, power tube type etc.
It's possible both of them burned and went to 10-K, but that would be odd.

I asked Mitch Colby: Here is the response: "Mark Kane (Cane?). Supposed to be a copy of an unusual one (some unusual value resistors) built by Dumble. Not all brand of resistors in Jim’s amp are as in original. I believe the original had many Pihers, some Dale and Mepco. Jim has been experimenting w...

Workmanship and components look like it could be a Krinard. Was just inside a ‘73 Deluxe Reverb that he worked over. Something that never should’ve been released into the wild. At least those appear to be soldered connections. FWIW: I would be surprised if it was a Krinard build, it's a bit too nea...

Workmanship and components look like it could be a Krinard. Was just inside a ‘73 Deluxe Reverb that he worked over. Something that never should’ve been released into the wild. At least those appear to be soldered connections. Some of the Krinard prototypes and early K&M or TR amps were frankly, fr...

I don't think that was built by Dumble. I could be wrong, but I doubt it is. That's Mitch Colby in the background. He's a friend of Jims.
I don't know for sure, but I don't believe HAD made any Bassman overdrive amps like that. Part choices could have easily come from here...lol.

I'm told, he had a bunch of storage units that were literally packed with amps, cabinets, power tools, test gear, etc. A few in Northern California and a few in the LA area as well. Apparently, they were at least labeled as to who owned what. I understand a guitar maker friend of Howard's in Califor...

sergio wrote: ↑Fri Dec 16, 2022 8:44 am HI Roberto , thanks.
TO3 transistor I think is in place to limit current?

I suspect it's possibly DC tube filaments and/or relay or optocoupler DC supply regulation (or both).

Looking at that schematic, ignoring the sonic circuit side of it, the power supply AC connection could actually electrocute you. You see this right? The AC hot wire (Black) should go through the fuse and then the switch and then connect to the primary, the return AC path (White) should be a solid c...

Having 2 Jim Kellys, I can say ,it‘s not a problem with JJ‘s.One has 470v, the other about 460v on the plates. High Plate Voltages are not so much problematic,High Screen Voltages can be. These are great amps! Jim Kelley is of the opinion that it's current that kills tubes, not voltage. I partially...

Sure. It was an active model for some time. Fender style input channels and 4 x 6V6's running at a blazing 500 volts.
It also had an outboard attenuator that allowed a master volume of sorts.

Does anyone know what sort of transformers Dumble would typically use in his 50W ODS builds? Any idea what might be in this amp? Most probably a Fender Bassman Yes, usually Bassman Iron, sometimes Magic Parts outputs. A friend who visited his place, told me he had "mountains of old Fender chassis" ...

@talbany, the Nichicon Black Gate's are absolutely f*cking amazing as cathode bypass caps. Nothing I've tried comes close, even bypassing with mica, ceramic, mylar etc....sad they don't make them anymore..... Yes Andy I remember you mentioning that a while ago about the Black Gates. Have been keepi...

I use 470's in Blues Juniors and most EL-84 amps in general. A few tech friends go as high as 1-K. 100-Ohms is dangerously low, especially with modern tubes. Matchless has been known for years as a company that runs power tubes to insane currents. Raise the screens, if it's cathode bias, change that...

"perhaps the problem is the balance or how and where that gain is utilized?"

Bingo.