Tube Amp Archive

Funkalicousgroove wrote: MikeKCA-- Great to see you here!! Glad you found your way!

Thanks. Did you get my email about the tubes? They went out today.

Blu-do! Blu-do! Blu-do! (Chanting)

Hi, I have a Fender '65 Deluxe Reverb (reissue) and I wanted to know if I can mod it to sound more like a Dumble? I'm pretty sure that he based the Dumble amps off a Fender Deluxe but with more volume. By the way is this true? Thanks I don't think he used Deluxes due to the relatively low power, bu...

Yup - agreed, but from looking at the Komet pics, it looks like there are 4 mallory 80uF caps (2 on top of the board, 2 under) with a small army of 220k escorts. For Komets, the cost of a capacitor is probably not an issue, and I think the TC80s are already rated at 450volts (?), so they are stacki...

Thanks Moose. The big issue for me now is I'm getting quite a bit of hum (120 hz?) from somewhere after the volume control. Haven't had a chance to dig in yet. Man, this thing is LOUD with the 6L6 power section! No way I'd ever be able to use it above 3 or 4 at a gig. Can't wait to try a master volu...

Thanks all. Problem solved. Turned out to be the negative feedback circuit in the amp I was converting (Bassman AB165). It was loading down the output from the 3rd stage. I disconnected the NFB temporarily and the amp is MUCH louder and starts breaking up at about 3. I'll have to reconfigure the NFB...

Thanks Toddy Joe. I have since lowered the voltages in the preamp...not sure of the plate voltage but the power supply side of the plate load resistor is about 260- to 270 if I recall. I'm sure that increasing the value of the 10K would add more gain and make it clip, but I think I must have somethi...

Thanks Moose. I've measured most resistors and pots to be sure but I'll check again. I actually replaced the treble pot with a 1 Meg with pull switch (for bright or semi bright switch). Not sure which 820 you're talking about as a grid stopper. The only ones I have are the 1.5Ks on the power tubes. ...

Thanks guys. I started with version A1 with higher plate voltages in the preamp (using a Bassman AB165 as a proto bed). I got the power supply voltages very close (mid 200s) and the amp still didn't break up significantly until dimed. I increased the stage III input resistor to 150K and I'm getting ...

Ross:
I've been thinking about a 1Meg Pre-PI MV with a pull switch in engage/disengage the pot.

Do you get the same amount of grind when you back off on the PI? I'm wondering how much extra distortion the PI produces under normal operating conditions.

Does anyone have Oscilloscope signal traces of various stages in their clone? Alternately, peak-to-peak signal readings at various points would be helpful. I'm using a Bassman head as a prototyping platform and initial results show much lower gain than expected. At 10, there's a nice crunchy tone fo...