Tube Amp Archive

Many Thanks for looking at this. My new signal generator arrived which is much better and I have taken a comprehensive fresh set of readings. I have established that Vin = Vout at the master Vol with the reverb circuit removed, but not when it is in place. I have taken a lot or readings with it in ...

On the voltage chart the problem seems to be between the MV (2,9V rms) and phase inverter input (60mv)

Looking at the phase inverter, what is the value of the grid resistor on pin 2. It looks like a 1k resistor, it should be 1M. The grid resistor on pin 7 is not visible, but should also be 1M.

As i'm sure you all know, the story is that the Roy brothers imported Dumble and Mesa boogie amps in the late 70's before making their own amps under the Kitty Hawk brand. They supposedly also imported a Dumble export model which was only the assembled chassis without transformers, tubes and cabinet...

I looked at your pictures and wonder what output transformer you use? On most output transformers the primary winding would be red, blue, brown, with red being the centre tap. On your amp there is a red wire that goes to the anodes on one side and brown going to the anodes of the other tube pair. An...

Hi everyone, I’m gearing up to build a Dumble 183 clone, and I called Chris Merren but he seems to be phasing out. I found amp parts direct and they seem to only offer a heyboer project 100watt out transformer with 2.2k primary resistance. I’m just wondering if anyone has used this transformer? How...

Ah yes, that makes sense.

picture sss build.jpg Looking good, however the 500ohm/5w resistors are very close to the Grid1 terminals on your power tubes. Those two points combine to make the highest voltage potential in the amp; Bias- to B+. That's putting a LOT of faith in the resistor coating to insulate against. If it wer...

I ordered solid wire during my materials gathering, and that has been more difficult to run nice and straight, my wire looks wrinkled. To staighten solid core wire, grab both ends of the (bare) wire with a plier (one in each hand) Bring both pliers together and the pull them apart quick and with so...

timrobertson100 wrote: ↑Tue Dec 17, 2024 7:05 pm What did you do with your mid switch please? I’ve tried various things people have suggested but never been satisfied.

I found that putting a 1uF cap over the 270 ohm resistor in the phase inverter works great and is like other mid/accent switches seen in early amps

C5 is not there to eliminate highs at the input. It is there to block RF from entering the amps circuit by creating an ac ground to chassis directly at the input. You see these caps in amps that have isolated input jacks / star ground to chassis. That's what I suspected the purpose was. I edited th...

C5 is not there to eliminate highs at the input. It is there to block RF from entering the amps circuit by creating an ac ground to chassis directly at the input. You see these caps in amps that have isolated input jacks / star ground to chassis.

For me personaly no F&T's. I don't like the sound of etched foil electrolytic caps in the power supply. I mostly use Mundorf and sometimes others with smooth foil.
They are a little bigger in size though.

Good to hear you found the problem. I don't really understand why Nik has changed things and put the transformer inside the chassis. But he is a very helpful guy so i'm sure it will be solved.

I have the exact same Ceriatone C'lator with five differences: 1. The transformer is outside the chassis. 2. All metal parts are have reference ground to chassis (pots, switches etc.) 3. High quality shielded cable.(Both inside the unit and to connect the unit to an amp) 4. Two chassis grounds. (1= ...

The chassis and lid are made of steel. This could explain vibrations. Especially when it lays lose on top of the chassis.

The transformer in the enclosure was probably not the best idea Nik had. I dont understand it either because it looks like the exact same PT, except the bell cover.