A short ago a friend of mine asked for help in repairing this amp he bought assembled. The problem was in the difficulty of trimming the bias (Iq): as soon as he turned the trimmer to increase the bias, he was not able to go over 20mA because the current drawing turned very strong at once.
I found the cause to be C6 and C7, which nulled the degeneration of T8 and T9 (R23, R27) at a frequency around 160KHz, leading the final stage to oscillate.
Once removed C6 and C7 the problem was solved.
I hope this could help the DIYers (mainly Italian) who still have "The Audio Amp".
I found the cause to be C6 and C7, which nulled the degeneration of T8 and T9 (R23, R27) at a frequency around 160KHz, leading the final stage to oscillate.
Once removed C6 and C7 the problem was solved.
I hope this could help the DIYers (mainly Italian) who still have "The Audio Amp".
