July 15th, 2016, 1:30 pm
July 15th, 2016, 2:26 pm
July 15th, 2016, 3:02 pm
July 15th, 2016, 4:18 pm
July 15th, 2016, 4:18 pm
justinis wrote:If I change the choke won't the resulted be unregulated? As in, as the amp pull more current (when the volume is high, say) the B+ will sag?
July 15th, 2016, 5:18 pm
July 15th, 2016, 5:38 pm
July 15th, 2016, 5:52 pm
justinis wrote:I tested with the amp biased and the input grounded (20mA cathode current on all 4 output tubes), however it was probably worse than normal because my B+ was higher than I want.
If I was only talking about dropping 20V or so I would totally understand sticking a resistive load in there. But I need to drop 65V, which at my idle current of ~100mA is 650 ohms. If my current varies by 20% I'll drop 13V extra volts. Is that kindof sag OK? If it would work just as well to put a 650 ohm L or R right after the rectifier I'm all for it.
Rectifier voltage drops can't be purely resistive, can they? From what I can tell they're specified on the datasheets without any current dependency.
I don't intend to "regulate" the B+ really. I just meant if I use the zener method then B+ won't be as dependent on output current.
July 15th, 2016, 6:05 pm
FerdinandII wrote:I just SIM'd the PSU circuit, and indeed the 5R4 will drop about 50VDC.
I'm curious what your line voltage is, and the AC voltage on the secondary of the transformer. It's supposed to be 370-0-370.
J-ROB wrote:Otherwise, you can get away with murder, at least until you figure out what is murder and what is not.
July 15th, 2016, 6:16 pm
justinis wrote:FerdinandII wrote:I just SIM'd the PSU circuit, and indeed the 5R4 will drop about 50VDC.
I'm curious what your line voltage is, and the AC voltage on the secondary of the transformer. It's supposed to be 370-0-370.
Thanks! Source is 120 Vrms. The voltage across the secondary is 781 VRMS, so I think that means 390-0-390. I figured this kind of discrepancy wasn't a big deal. I've heard line voltage was lower when these transformers were made, like 110V.J-ROB wrote:Otherwise, you can get away with murder, at least until you figure out what is murder and what is not.
Is a 650 ohm resistor after the rectifier "murder?"