So last night I was trying to clean up my room and I realized that I might have enough parts on hand to build a parallel push pull 6E5P amplifier in class A. I would use an input transformer for the gain and phase splitting, so no preamp tube to worry about.
The only hesitation I have is the power transformer. I have a 100VA 300v antek power transformer.
It has 2 300v windings both rated at 170ma each. If I put the two windings in parallel, and use a choke input filter, I should have 319.6ma available.
If I have 8 6E5Ps all biased at ~40ma of current, that would be 320ma which is obviously just high of the limit. I could obviously bias the tubes a little bit lower, but I am still very close to the saturating current of the transformer no matter how you look at it.
I normally overrate my transformers by quite a bit, but since this is a junk box amp, maybe it doesn't matter all that much. What do you guys think?
The only hesitation I have is the power transformer. I have a 100VA 300v antek power transformer.
It has 2 300v windings both rated at 170ma each. If I put the two windings in parallel, and use a choke input filter, I should have 319.6ma available.
If I have 8 6E5Ps all biased at ~40ma of current, that would be 320ma which is obviously just high of the limit. I could obviously bias the tubes a little bit lower, but I am still very close to the saturating current of the transformer no matter how you look at it.
I normally overrate my transformers by quite a bit, but since this is a junk box amp, maybe it doesn't matter all that much. What do you guys think?
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AnTek "iron" is not flimsy and true choke I/P filters can deliver a tad more B+ current than the rated RMS current of the winding(s). What can't be tolerated here is the current loss in a critical current bleeder resistor. So, all signal tubes must be fully warmed up and emitting, before B+ rise occurs. A straight forward (IMO) way to accomplish that which is necessary is hybrid bridge rectifying the paralleled 300 VAC windings with 2X 600 PIV Schottky diodes and 2X 6CJ3 damper diodes. The forward voltage drop in that brute of a damper diode is remarkably small, when compared to that in "typical" vacuum rectifiers.
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