One other note about "classic" tube amps: most had pretty severe
limiting (or roll-off) networks built into the input circuits. Remember
that "back in the day", designers probably weren't going for flat
response from 20Hz-20kHz. Adequate performance was 40Hz to 10kHz. They
didn't see the point in the amplifier amplifying "noise", so they
limited the response of the circuit. Most "classic" sounding tube
pieces can have the limiting circuit modified or even removed and have
the overall feedback loop reduced (by feeding the amplifier a 10kHz
square wave and reducing feedback until ringing occurs on the 'scope,
and then adding some feedback back into the circuit). After the
feedback is reduced, worn out parts are replaced and the limiting
circuit modified, you'd be surprised how much of the "classic" tone
disappears.
Phillip

Steven C. Barr(x) wrote:
> ----- Original Message -----
> From: "Roger and Allison Kulp" <[log in to unmask]>
>
>> I have never seen an RCA stand-alone amp,like the one seen at 4:01 in this
>>
> clip.Once in a very rare while,I will see an older RCA amp,made for movie
> theaters.I had one once,circa 1943.I found it in a dumpster in
> 1988.Unfortunately,someone stole it from me when I was moving,a few years later.
> once.I had an RCA tube tape deck like that,and sold it on eBay,in 2005.
>
> Note that there was also an amp intended for home-movie use, for which the
> speaker cabinet was boldly labelled "Victor" in metal letters mounted in
> front of its grille cloth; this was NOT "RCA Victor" and, indeed had no
> connection with that firm.
>
> I have one of the cabinets (speaker long since defunct)...and have seen
> one other such...
>
> Steven C. Barr
>
>