[HAM] [HL] 147 "helicopter" noise at low volume *Follow Up*

[Hugh]

>
>In years of working on amps, I have learned that there's no sane answer to
>that kind of question. What other "techs" do to amps seems to be infinite
>in its seemingly-random lack of sense or attention to specifications. It's
>almost like asking why does Johnny huff the oven cleaner?

I think Johnny the tech must have huffed the oven cleaner. The amp 
was practically useless. However, you could play one note at a time 
without distortion. Once there was intermodulation though, it was all 
over. Maybe the Tannoy crossover somehow kept the oscillation in 
check. The Tannoy was in a home made tone cabinet for a BC, so I 
can't see why they were striving for high frequency.


> >I assume originally ceramic caps weren't used here. What is the
> >original type of these caps?
>
>Mica. Be certain that it is at least 1KW! A little bit harder to find, but
>they're out there.

Of course you mean 1 KV, not Watt. Will there be a degradation of 
performance keeping the ceramics in there? They're not NPO so they 
will drift maybe 10% with temp, but is that really critical when it's 
to damp oscillation?

Thanks,
Hugh


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