[Phil Allison[_3_]]

"John L Stewart"
'Phil Allison


Sounds like by either intent or serendipity the 300B and 6SN7 2'nd
harmonics are canceling.-


** Bingo !!

Seems an eccentric Russian gent was responsible for the circuit design.


There was an article on 2H cancellation in SE amps published about 10
years ago, I think in Glass Audio. Used the curvature of the driver to
cancel curvature in the OP Tride. One would think this possible at only
one level on the output.

** More testing with the FFT feature on a Rigol scope:

3H is dominant from about 9 watts through to 21 watts.

From 1watt to 4 watts, 2H dominates, then 4H, then 3H.

If load R is changed to 16 ohms, 2H dominates all the way.

2H cancellation is occurring over a fairly wide range, but it is not
complete.

I can swap the 6SN7 with almost no change.

Neat eh ?


..... Phil