• 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.

Direct heated tubes with centre tap on filament

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Blitz

Member
Joined 2002
Intersting...I am not sure I know any of those (coming from Europe)...which ones can you recommend worth trying ? Ideally which ones have you heard yourself and can testify they sound good (I believe that there is still an engineering factor which goes beyond data sheet facts which makes a tube sound good or bad, be it the form or the metal/chemicals used, see thoriated tingsten filaments etc.).
 
kASD

kASD

Member
Joined 2004
Blitz said:
So, I turned the negative reg legs now to connected cathodes/CCS instead. Bingo !!! Now we have it: The image is there, the phase is very natural and we have micro and macro dynamics. The magnitude of the difference I would rate in the same category like changing from an OK cap to a real good one.
Click to expand...

In my fully balanced implementation, I had tied the negative sides of the cathode through ac coupling which definitely gave better results, since each tube has its own ccs (apart from separate gyrator + ccs for each floating filament) to get away with any mismatch ànd aging effects and current is held constant at 40mA
 
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