Preamp Tubes for DR-103

[therealjoeblow]

Hi all,

I know that in traditional cathode follower applications you can't use spiral filiment type tubes because the maximum cathode-to-heater rating of 100 volts is exceeded, which causes them to fail very quickly. This rules out anything (current production) from New Sensor for that position on a Marhsall or similar amp (Tungsol, Mullard, Sovtek RI's).

I also know that V3 in the DR-103 has been described as NOT being a Cathode Follower, but instead just providing a reference voltage for the phase inverter. Does that mean I would be OK using the (current production) Tungsol in that position on the Hiwatt (and in all other preamp positions)?

Many thanks
TRJB

[mhuss]

The V4 voltage reference normally runs about 70-80 volts on the cathode, so it should be OK.