The Amp Garage

I'm going to have a couple of these boards made and see how they turn out (and how much I have to learn). A few tips : - Configure your own DRC with sensible values (default is 8 mils, OK for LV apps but way too small for HV - use 100 mils, even if your boards will be varnished or coated), save you...

Cool about KiCAD. I'll check that out too before I plunk down the $$ for Eagle.

I downloaded the free version of Eagle and quickly drew up a 5f2 Princeton schematic and board. This looks like it might be a winner at the low, low price of $1500 for the full version. I'm going to have a couple of these boards made and see how they turn out (and how much I have to learn). Anywho, ...

Hey, thanks for the suggestion, but they appear to be all about 2D and 3D CAD software. I don't see any PCB stuff unless I'm missing something.

Has anyone gone there yet? I'm looking for some good, tube amp ready, PCB design software, and I'm willing to pay for it. Does anyone have any experience with the good stuff (no Express PCB). I want Gerber files for output, not some sort of proprietery thing.

The phase cancellation MV is wonky unless you use 1 or 2% resistors throughout the PI. At least that's been my experience with it.

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer? Many Dumble amps have local negative feedback on the second gain stage. It is a resistor (typically 22M or 44M) from the anode back to the grid (through a coupling cap). You'll find it on many of the schemati...

Forgive my dimwittedness, but what is the local negative feedback loop to which you refer?

Well, I have to admit to being inspired by some clips I've seen of the John Mayer 2-Rock played clean...

And I've only built D'Lite kits for other people. I've never done anything in Dumbleland myself and this seems like a good excuse to mess around there.

I'm interested in building a Dumblesque amp just for clean tones. With all the information here, I'm not exactly clear on which direction would get me there.

So if you Dumbly experts were only interested in building the best possible clean channel, how would you proceed?

...a triode and instead of going silent, it buzzes and hums? It's wire is picking up some RFI, but when I ground it, it actually gets worse.

What am I not thinking of here?

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This guy said he's taken this amp to half a dozen techs over the years and no one could fix it. So I'm glad to be able to help him out.

As it turns out, he insisted I charge him 2 hours for it and wants me to do a cap job on it now, so it's all good

OK. I finally figured it out. I think there was a conspiracy in the Fender factory in the 60s to drive me nuts. Anyway, there was a whisker on the tube socket that was causing me pain and shorting the LDR. Once I found that (it was hiding behind the filament wires), the circuit started functioning a...

Thanks for the ideas, guys! I've checked the pots. Those are correct and functioning normally. The cathode resistors are indeed grounded. I do have a footswitch plugged in. I know that one :) That's just it! This should be a no-brainer, but it has me stumped! All the caps and resistors measure corre...