Long story short:
I'm struggling a bit with the power supply for my 808 SE amp. The first power transformer I tried (AnTek toroid) both vibrated and produced a too low HT so I replaced it with an old EI transformer from a 1940's cinema amp. My mains voltage is 230-235V and the transformer has taps for 220 and 245V. The 220V tap results in the right heater voltage for the 4x 6AU4GTA rectifiers but the HT gets a bit on the high side while the 245V tap gives a more comfortable HT (and less mechanical noise) but only 5,8-5,9V to the rectifier heaters.
How important is this in the real world? The datasheet mentions 6,3V +-10%, that would be 5,67V for a minimun.
I'm struggling a bit with the power supply for my 808 SE amp. The first power transformer I tried (AnTek toroid) both vibrated and produced a too low HT so I replaced it with an old EI transformer from a 1940's cinema amp. My mains voltage is 230-235V and the transformer has taps for 220 and 245V. The 220V tap results in the right heater voltage for the 4x 6AU4GTA rectifiers but the HT gets a bit on the high side while the 245V tap gives a more comfortable HT (and less mechanical noise) but only 5,8-5,9V to the rectifier heaters.
How important is this in the real world? The datasheet mentions 6,3V +-10%, that would be 5,67V for a minimun.
The screws are tight and the transformer i completely soaked in varnish + mounted on rubber dampers.
The main problem here is probably my PSU chassis design, flat sheets of 2mm alu assembled with alu profiles in the corners.
I ran the amp for a couple of hours this evening and the transformer got quite hot. I'll probably have to rebuild the whole thing in a better chassis but I'll try the 245V tap first and se if that does anything against the noise problem. If so, I can probably solve the heater voltage issues with a separate heater transformer.