"Mike Gilmour" wrote in
message
"Bret Ludwig" wrote in message
oups.com...

Ruud Broens wrote:

snip


The opamp is *designed* to use large amounts of
linearising
feedback, something that simply isn't an option with
the inherently much lower open-loop gain of tubes.


Philbrick and Julie were building perfectly proper op
amps with tubes as early as 1943, but thanks for playing.

Part of my theory training was the K2-W :-)

I started out on a EAI TR-48 as an undergraduate:

http://archive.computerhistory.org/r....102646218.pdf

and moved on to the 680 in my senior year and in graduate school:

http://archive.computerhistory.org/r....102646244.pdf

The digital side of the system was an IBM 1130. We did not use the EAI
interface box, but instead used a third party interface that included a 200
KHz true 16 bit ADC/DAC box with 16-way multiplexors, in and out.