Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Gregwor on April 17, 2021, 12:22:13 pm

Title: ECC82 cascode push pull
Post by: Gregwor on April 17, 2021, 12:22:13 pm
My mind is toying with the idea of somehow maybe incorporating a lower output option on an amp that would switch from a pair of 6L6 to a pair of cascode ECC82 in push pull. Is there any things you guys can think of why this would be a horrible idea? I've never really explored switching output tubes/configurations. I'm seeing amps such as the Traynor DH15H that appears to switch over to a pair of single triode ECC82 in push pull but they keep the plates of both types of output tubes connected to a single primary OP tranny -- I assume this is to keep the source load on the tranny more consistent? I have to look into it/think about it more, but I wonder if switching between the tubes could be achieved like Randall Smith does in his early output reduction circuits by simply removing the cathodes connection to ground (along with obvious biasing and input signal routing between the 6L6 and cascode pairs). Just spit balling here but would love to hear others thoughts on this.

Ultimately, I'd love to have full output 6L6 pentode, medium output 6L6 triode, lower output ECC82 cascode, and silent reactive loadbox output to drive speaker emulation driven from the cascode pair. A tall order, I know.

I hope you're all staying safe and having fun! Thanks in advance for everything!

Greg
Title: Re: ECC82 cascode push pull
Post by: tubeswell on April 17, 2021, 10:50:56 pm
If you can find a speaker with high-enough impedance, you could try a transformerless SRPP with highish current triodes. Not tried it yet myself and no guarantees.
Title: Re: ECC82 cascode push pull
Post by: DummyLoad on April 18, 2021, 02:24:01 pm
6L6 tetrode

6L6 is not a tetrode.

Power Beam Pentode. G3 is tied to cathode, Tung Sol refers to the 5881 & 6L6GC as a beam pentode as do GE, et-al. pretty much everyone did after Phillips patents on the pentode expired.

--pete
Title: Re: ECC82 cascode push pull
Post by: Gregwor on April 19, 2021, 08:42:36 pm
Quote from: DummyLoad on April 18, 2021, 02:24:01 pm
6L6 tetrode

6L6 is not a tetrode.

Power Beam Pentode. G3 is tied to cathode, Tung Sol refers to the 5881 & 6L6GC as a beam pentode as do GE, et-al. pretty much everyone did after Phillips patents on the pentode expired.

--pete
Fixed. Dumb typo. Thanks for point that out!

Greg