The Amp Garage

really?

What were your HT, G,S,D, bias voltages?

Did you ever get a chance to play around with this?

Cool, looking forward to hearing how this works out

Try it, then you'll know for yourself if it has any merit.
No harm done as long as the tubes are used within their ratings.

Hah, yep, caps in wrong place. I scribbled it up quickly to stick in the post

I played around with a source-o-dyne feeding a pair of KT66's a while back, it behaved well and was transparent. This is the implementation I used. Probably should have G>S protection diodes and a gate stopper...

The last two amps I built used combination bias. The setup was recommended by Gingertube. The cathode resistor is approx 15% of what would normally be used for cathode bias. No bypass cap. The cathode feedback is the only feedback I used in the power section. Fixed bias provides the rest of the bias...

Thanks Sluckey. The waveform didn't really look familiar - was expecting it to just square off

I've been playing around with the B+ feeding the PI. When I took that scope shot, the B+ was at 230vdc and the bias at about -4vdc. The input to the pi grids was about 4vac. At 2vac input, the output of the PI looks normal. So is this the result of pulling grid current on the 12AU7 PI tube? Is this ...

The DCR of the choke is 600R as previouly stated, seems to be biased ok, a little over -6vdc on the grids: Choke Tail Load Line.jpg This is the Boozehound Labs circuit I borrowed from: BHL15.jpg His description: What we need is a device that has relatively low DC resistance so that it won't drop a l...

I'm playing around with a "choke tail" PI. Basically a LTP but instead of a tail and cathode resistor it uses a choke. 12AU7 with 33k anode resistors and the choke is 30h, 600 ohm DCR. With a sinewave at the input, the PI outputs are balanced but look like a square wave with a sawtooth on top :( Any...

Attached is the Cliff Chappell's 4-4-0 from AX84.

I built one of these way back. Crazy loud for a 2W amp. Pretty cool little amp.

I never loved the triode output section. I ended up rebuilding it with a big bottle PA and power scaling...

A pretty subjective question, but...
For the "typical" Dumble clean sound, are the bright, mid-boost, or deep circuits commonly engaged?

Thanks BrewDude, I did!