Tube for starters

[bpaz]

I have never seen a tube have 2nd and 6th as the predominant harmonics- can you describe the test setup and show the spectra?

My speakers are not flat, but i can see harmonics appears and disappears at 2 and 6 khz when switch. Is it true? Apparently not. I have repeated the test and now I can see the others harmonics between 2nd and 6th. Burn-in? Mistake? I dont know, sorry. Next time I will repeat before talk.

I have used a pair of electret mics suggested as replacement for panasonic wm61a, a 1khz wav file from audiocheck.net, a RTA softeare called Spectralissime, and a pair of switches for fast change between tubes and no tubes bypass, and my onboard sound card.

 

[SIY]

My speakers are not flat, but i can see harmonics appears and disappears at 2 and 6 khz when switch. Is it true? Apparently not. I have repeated the test and now I can see the others harmonics between 2nd and 6th. Burn-in? Mistake? I dont know, sorry. Next time I will repeat before talk.
View attachment 182555
I have used a pair of electret mics suggested as replacement for panasonic wm61a, a 1khz wav file from audiocheck.net, a RTA softeare called Spectralissime, and a pair of switches for fast change between tubes and no tubes bypass, and my onboard sound card.

The speakers and room will vastly dominate. The way to do this measurement properly is to do it electrically, not acoustically.

BTW, you're doing fine with English!