6AN8A Tube (Phase Inverter-1976 V4)

[danb435]

Stumbling upon the service notes on this site it mentions that Ampeg used a 6AN8A tube with a spiral heater element to reduce hum in the 1976 distortion model V4/VT22. Does anyone know the manufacturer of this original tube? Or, to the experts out there, would converting this lone tube to a DC heater supply have the same net effect?

[Hangman]

Thats a really good question... I have some replacement parts lists that ampeg service centers got but they are from may 1975 and june 1976. The service memo was october of 1976. there isn't 6AN8 in the 1975 parts list, there is only one in the 1976 list, but it doesn't give a brand or anything.

I think a DC filament supply would definitely help the hum for that tube, and might just be there better way to go.

[danb435]

Thats a really good question... I have some replacement parts lists that ampeg service centers got but they are from may 1975 and june 1976. The service memo was october of 1976. there isn't 6AN8 in the 1975 parts list, there is only one in the 1976 list, but it doesn't give a brand or anything.

I think a DC filament supply would definitely help the hum for that tube, and might just be there better way to go.

Thanks Hangman. If I'm remembering correctly the Ampeg trannies are somewhat overrated and fairly stout, do you believe the heater windings in the PT would handle the added load of rectifying and filtering the AC filament power to DC for all the preamp and phase inverter tubes? This would raise the current draw from a little under 3 amps for those tubes to about twice that much if I am reading the specs correctly. The power tubes would remain with the AC heater supply. Thoughts anyone?