Over the weekend I tried to run some tests against my Tubelab SE (300b, mostly stock) amp. I was using Arta (ARTA Home) with the Pulsed Pink Noise in Spectrum Analyzer mode at what had to be close to maximum amplifier output. I also happen to have dual panel meters for my output tubes to monitor the bias. While performing the test, I noticed that the bias meters were dancing vigorously in time with the pink noise pulses. I panicked and stopped the test immediately. I didn't get a firm idea of the range, b/c I stopped the test so quickly. I would guess it was at least 15ma of difference (with the idle bias set to 65ma @ 388V).
I'm still learning, so I don't understand the schematic for the TSE well enough to know if this is normal or not. During normal music, the bias seems to drift back and forth a very wee bit but nothing like they did during the test. I played some music through the amp after, and it played well (so no damage was done - it seems). For reference, I've attached the result from Arta. The peaks below 300Hz are something in my test chain (there for any device/loopback).
Is this bias response to stress normal? If not, where do I need to look for improvements?
Thanks!
I'm still learning, so I don't understand the schematic for the TSE well enough to know if this is normal or not. During normal music, the bias seems to drift back and forth a very wee bit but nothing like they did during the test. I played some music through the amp after, and it played well (so no damage was done - it seems). For reference, I've attached the result from Arta. The peaks below 300Hz are something in my test chain (there for any device/loopback).
Is this bias response to stress normal? If not, where do I need to look for improvements?
Thanks!