The Amp Garage

Maybe a good question is: eventually when? #102 went through little mods since 1982/1983. Robben himself says that he went back to HAD shop soon after he got the amp and HAD did some changes. If you consider that to change that resistor degoop and regoop is needed, either the 150k has been put back ...

Hi everyone, I recently completed a Dumble clone 124. I am just fine tuning the amp now and trying to adjust but I found a few discrepancies -the plate voltages at V1 are 206 and 205 ~The plate voltages at V2 are 209 and 212 -the plate voltages at V3 are 312 and 319 The power tube plate voltages ar...

Yess correct, when V2b is overdriven the average/bias grid voltage goes more negative each time the signal swings positive generating grid current, until a new "equilibrium" point is reached (it gets very negative! even more than a few volts). When the signal decreases and V2b is less overdriven gri...

That resistor has also an important function in the dynamics of interstage current/voltages: when gate of V2b approaches voltage of V2b cathode, it start to draw current, that resistor determine the current into the gate, the higher the value the lower the current. Everything in between V2a plate an...

ijedouglas wrote: ↑Mon Nov 25, 2024 9:14 pm

erwin_ve wrote: ↑Mon Nov 25, 2024 2:42 pm ...

For history's sake:

Yup, same pic I have. Mid/Bass CTS and Treble Alpha/Mouser

Yess you are right! A better shot than the one I had

Mid pot CTS type usually have a 10-12% taper like Alphas

Is the bass pot a CTS 2-35?

..The mid and bass pots were also Mouser, 250k 15%, and the bass pot measured 400K. Can you confirm that when you worked on it the bass pot was a mouser? There's a pict of the amp (also here, not remember where) after skyline upgrade where the bass pot wasn't clearly marked mouser/alpha. It looked ...

Chicken knobs should be made mandatory on dumble amps!

Here is a video of him playing the amp live back in 1988. I believe that is his dumbleator sitting on top of it. I noticed the amp did sounded a little darker here with the dumbleator. It still sounds amazing!! I wonder if the ageing of the components over time also changed the sound of the amp. ht...

Yes, they are building again, I met Sergio at a guitar fair two weeks ago and it was showcasing their amps.

Regarding ODSs I wonder how many owners actually use power amp to generate their distortion sounds in order to put the PI into the gain equation... ? Anyway "gain" is not a universally well defined concept. If you mean "maximum overall voltage gain possible from input to speaker" bluesmaster should ...

... Hello Guy The amp is at least 10 years old and was constructed before Two Rock sold the company. IIRC the amp was constructed specifically for Robben to use as a backline rental so it would make some sense for them to try and get as close as possible to the sound of 102.. I cannot say for sure ...

I just set it where I like it...

(in my amps it's accessible directly from under chassis)

have fun

@ic-racer

agree with you 100%! we were talking 6L6s...

have fun
Teo

The OD side had so much clarity and command - no fizz but lotsa nice OD clarity - probably less intermodulation? Yes and no, biasing colder actually increases xover distortion a little in power amp which is a cause of IMD. But that's not that bad at all considering such an imperceptible IMD increas...