PP amp driven with balanced input source

[N101N]

jderimig,
I`d keep the design as is, well done!

The DAC makes an excellent splitter, and better still, the differential to SE function - which is usually done with opamps on the DAC board - is performed by the output transformer.

Rod Coleman,
the differential to SE function is not mandatory, you don`t have to utilise both outputs.

 

[Chris Hornbeck]

Because you can so easily bring the input valves' cathode current from the available bias supply, you might as well do that. Doesn't have to be an active CCS, can be just a resistor.


This makes the input differential, so minimizes common-mode stuff in the following stage(s). Also helps maintain signal balance for power supply immunity. Free and easy.


YOS,
Chris

 

[N101N]

Not everybody is in love with the differential pair, a small minority is not.

 

[Anchan]

I built an amp from two single ended tubelab boards to make a PP amp, and driven by a balanced dac without a phase splitter as you described:
Dual Simple SE's in Push Pull w Differential Input

 

[jderimig]

Review Design - Balanced input 6DQ6 UNSET output stage

Below is my current design. Using 6DQ6 in an UNSET output stage. Idle is about 17W (yes a little high) for a 50W output. Schematic and spice FFT sims attached. Driven by balanced output of DAC. Any modifications suggested?

 

[baudouin0]

Yes I would allow adjustment of the gate voltages to be separate with pots to set the current in each output valve. MOSFETS have a big spread of current which LTspice will not show. You could try ECC88 for first stage.

 

[NickKUK]

I'm not sure but check, V2 has B+Screen but there's B+ and there's Screen so I assume the to are connected but called the same thing?

 

[jderimig]

Thanks, just bad formatting on my view, Screen and B+ are separate.