thorsten we91 HF feedback loop problem

Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

a friend of mine
who cannot access a computer atm
finished his we91 thorsten clone yesterday
all voltages within margins (see below)
we gingerly fired it up in the system
to be greeted with howls and cycling whistles
these were significantly reduced when volume lowered
but would hit a point where the amp would seemingly hard clip
we removed the pair of mica caps
feeding back from 300b to 310a screen
and all is normal
sounds very good
but we would like to get the feedback stabilised
from memory:
HT is intentionally high at 460V using VV30B
Va 310a (STC substitute) was lower than expected running @2.5mA
any ideas please
dave

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VH Audio

Topic - thorsten we91 HF feedback loop problem - smelly 04:43:05 02/19/06 (2)

Re: thorsten we91 HF feedback loop problem - Thorsten 04:53:23 02/21/06 (1)

Re: thorsten we91 HF feedback loop problem - smelly 03:01:10 02/22/06 (0)

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