• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Differential amplifier with DH tubes

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi

I ordered 24x 4P1L and plan to build a fully differential PP (three pairs in // triode connected, OPT=4.2K/8R). Operating point about 250V 25mA per tube, it seems to be correct. Fixed bias.

I'd like to keep things simple but have no experience regarding DH tubes.
My idea was to heat them by AC 4.2V with filament CT to ground.

Probably not the best option running DH tubes this way but as it will be a fully differential amplifier, noise and hum is supposed to cancel quite well.

Even if it won't be the ultimate solution, can I expect good results? is it better to run the heaters in // at 2.1V and use hum pots?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.