what is “”than that”, atmasphere?
Push-Pull amp tubes misbalance cause increase of odd harmonics, even 5% misbalance is causing more that 0.1% dist. increase easily.
keeping tube amp in a good performance condition is very costly, period. if not, you’ve got a “romance”
@westcoastaudiophile
The statement to which I was responding mentioned that bias would be shifting in as little as 50 hours as well as resistors and capacitors. The simple fact is any tube amp is far more stable than that.
FWIW an imbalance in power tubes will cause a 2nd harmonic, not a third. The push-pull nature of the amp will cancel a lot of it but some will still be present due to the mismatch itself. Also FWIW dept.: the 3rd harmonic is treated much the same way by the ear/brain system as the 2nd in that it tends to be innocuous. Like the 2nd it does have the advantage in a tube amp of masking higher ordered harmonics- that is literally why tube amps tend to be smoother than traditional solid state (class D amps can make lower ordered harmonics in the same way, so they can share this characteristic with tubes depending on the design).
You are right about tubes being costly! They have always been expensive, which is why high efficiency speakers were so common back when tubes were the only game in town.