[morzh]

Well, using my Variac I found that each input winding's half of my output transformer has the ratio of 30:1 to the output winding. Which makes the impedance transfer as 900. So, 6 Ohm of my speaker look like 5.4kOhm to each tube and the optimum is 3.9kOhm which is not too bad.
Plus I tried the Yamaha and it is declared 4 Ohm which makes it 3.6kOhm which is right where it needs to be and it still distorts.

So. It is not the speaker OR the output transformer.
Nice to know.


PS. The programming on the station has suddenly changed and they have that doo-wop and the distortion went way up.
Well, I turned on my 37-116....and it also kinda distorted, so at least that worsening was not due to the radio itself.