I didn't... But, I estimated conservatively in my recent simulation. Still, PSUD claimed the transformer was putting out almost double the current draw.
Top plate and Russian caps finally came in, so the amp is back up and running.
The power tranny still gets hot and has a slight vibration, but doesn't seem to be aggressively buzzing anymore. I placed a 0.51-ohm resistor in series with the 6.3V line to ease the heater load a bit.
Is it a good idea to ground the neutral speaker connection? I am currently running them floating with no apparent issues.
Thanks to all for the tips!
The power tranny still gets hot and has a slight vibration, but doesn't seem to be aggressively buzzing anymore. I placed a 0.51-ohm resistor in series with the 6.3V line to ease the heater load a bit.
Is it a good idea to ground the neutral speaker connection? I am currently running them floating with no apparent issues.
Thanks to all for the tips!
I was throwing one together today because I had a couple of generic 5k OPT lying around and several 1626s, like yourself I thought it was a little hot and after experimenting I found a 2k2 cathode resister was an ideal size. With 300 odd volts on the OPT the tube gets about 36V dropped on the resistor making it 16mA. With 250V on the tube now ( Maximum stated on RCA data sheet) makes the dissipation around 4W. A nice snug value me thinks 😉 Still working on the driver tube, maybe a 12AT7? any suggestions people?😀
AC current draw from the transformer winding is not the same as DC current draw by the actual audio circuit.
The AC loop goes like this:
One end of transformer winding -> diode -> first cap -> other end of transformer winding.
Use series resistance before the first cap.If the cap is big enough, the cap is (partially) a short for AC so putting some series seristance will bring the current down in that loop.
I've built five or six different Darling circuits, and I found that the 1626 will do just fine for at least a year with 9.5W dissipation. (I disassembled the last Darling amp after a year as parts for other projects. Tubes hadn't failed.)
I found the sound best at 250V and 32mA.
In my experience in Darling amps; for serious use, shared cathodes is not a good idea. Only for novelty builds.
The AC loop goes like this:
One end of transformer winding -> diode -> first cap -> other end of transformer winding.
Use series resistance before the first cap.If the cap is big enough, the cap is (partially) a short for AC so putting some series seristance will bring the current down in that loop.
I've built five or six different Darling circuits, and I found that the 1626 will do just fine for at least a year with 9.5W dissipation. (I disassembled the last Darling amp after a year as parts for other projects. Tubes hadn't failed.)
I found the sound best at 250V and 32mA.
In my experience in Darling amps; for serious use, shared cathodes is not a good idea. Only for novelty builds.
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