I have been tinkering with the feedback ratio in a VTA-70
( low gain model with CCS and 12au7, EL34 finals)
By examining distortion spectra i found that 2k as R7 R8 seems
reasonable ( down from 7.5k)
In order to calculate the NFB i need to know the open loop gain.
Yes, i forgot to disconnect the feedback and measure when it
was on the bench. Anyone that has the value ?
Last edited by peterh on Tue Mar 24, 2020 2:18 pm; edited 2 times in total (Reason for editing : spelling)