[Ian Bell[_2_]]

Arny Krueger wrote:
"Ian Bell" wrote in message

Eeyore wrote:
Ian Bell wrote:

Since there are untold preamp designs with unregulated
supplies
Bad preamps you mean ?

Graham


You tell me. I have the schematics for many broadcast
consoles and professional music mixers from the 50s that
use unregulated supplies.

Standards for audio were a lot lower in the 50s, if you didn't ever notice
when you listened to a lot of recordings from that time. There are some
exceptional recordings that still sound good, but in general, it was not a
good time for quality sound reproduction.



I would not say they were a lot lower. The flat bandwidth extended only
from 50Hz to 15KHz but elsewhere the specs were close to today's. An RCA
broadcast console achieved a 68dB S/N ratio with a -60dBm input signal
which implies an equivalent input noise of -128dBm - and that would not
be achievable with the LF noise I am seeing right now. Maybe they had
better conditioned mains supplies for studios or maybe there was just
less crap on the mains in those days.

Cheers

Ian