Re: Which tube expert can do custom works?

In article <Ds3oj.289338$oB2.40477@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Iain Churches" <IainNG@xxxxxxxxxxx> wrote:

"John Byrns" <byrnsj@xxxxxxxxxxxxx> wrote in message
news:byrnsj-AA68E6.15142229012008@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


The BBC seems to have used "low level mixing" as late as the 1950s,
necessitating only one microphone amplifier for typically 4 microphones.


There are some interesting BBC pics of Type A equipment at:

http://www.btinternet.com/~roger.beckwith/bh/typea/typea1.htm

Interesting, I have a BBC "Training Manual"/Book from 1955 that has a
couple of pages that describe the Type A equipment along with a block
diagram of the mixers components. More to the point of this thread the
book also includes an approximate schematic diagram of the AMC/2 "A" or
microphone amplifier mentioned on the web site in connection with the
Type A equipment. It is interesting in that the AMC/2 amplifier uses a
single pentode tube/valve with shunt feedback, probably not a topology
that would find great favor with this group.


Regards,

John Byrns

--
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