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Lowery 6550 PP organ amps.


mike stehr

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Now you aren't getting all worked up, are ya?2.gif

The Tung-Sol's in the back amplifier are pretty much wanked at 50%, the GE's a little better at 80%.

The ol' timer just kicked them down with the amps to use to get them operating, he does have a pair of strong Tung-Sol 6550's that I could coax him out of.

"By the way are you going to be able the stand the power LOL !!!!!!"

Oh, I'll love it.

These are set up with around 600 volts on the plates, with 300 volts on the screens with a 6V6 screen regulator.

Primary impedance on the output transformer is around 3550 ohms. So something like 80 watts should be realized from what I understand.

One amp works, but it's limping along. The driver circuit is a 6SN7 gainer/inverter stage. The driver stage doesn't seem to get enough gain to get any power out of the output.

The circuits are ancient, and need to be revised.

The output tubes are cathode biased, I already have little transformers to build negative bias supplies with pots on the grids. We are still pondering on what sort of driver stage to use. Paraphase inverter possibly, or a center-tapped interstage transformer to use as a splitter.

It's all up in the air.

I've been attempting schematic drawings, but it's about time to hit up the local organ joints in town.

I could always pinch the PS transformers to use for a SV811-10 triode project. They have a secondary voltage of close to 1000 volts, just right for the Svetlana SV811-10.

I have nice pair of James 20 watt air-gapped OPT's to use for that.

I could source some 450, 500 volt PS transformers to use in the organ amps. Then I could use other types of output tubes.

I'm losing my mind.....

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