• 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.

Sonics of a "dynamic coupled" driver


2007-07-12 1:42 am
Yes, great site, lotsa nice gear too. I've see similar designs using transmitter tubes (I have a nice pair of 808's as well, could buy them NOS JAN army surplus for 95 cents when I was a kid). These tubes are designed with positive grid drive as normal operation so you have two choices, get a driver transformer or the use the dynamic coupled approach. Effectively a class A2 amplifier.

Not sure about pluses and/or minuses... but the dynamic coupled circuit has to keep the grid positive at all times otherwise the driver stage goes into cutoff (probably a minus). It does allow for much lower voltages than the tubes are normally operated at (certainly a plus). Still, I think a transformer driver setup should be better but the cost is much higher.

If you look at the tube data sheet linked here:


You'll note that 300 watts output is capable under ICAS conditions... but around 200 watts is good for CCS operation with class B operation.

Regards, KM