[Don Pearce[_3_]]

On Wed, 27 Nov 2019 15:49:00 +0000 (UTC), Rick Ruskin
wrote:

On 27 Nov 2019 09:28:21 -0500, (Scott Dorsey) wrote:

Rick Ruskin wrote:
I have a trio of racked 101 preamps with 502 eq's. Can anyone
recommend an input transformer with a reasonable step-up to increase
the gain up from the 40db max they deliver now?

No, because the input impedance on those is already 600 ohms. It is
dominated by the emitter resistor on Q1. If you put a step-up transformer
on there, you get an even lower input impedance which is probably not
what you want.

There's no free gain to be had here.
Not that a 1:1 transformer might not help the miserable CMRR on those things.
--scott


The current version of these units state 64db of gain with the same
101 card. Where is the extra gain coming from?

RR

Probably an extra stage of amplification, or if the design allows, a
change of feedback resistors to get more gain from the existing
circuit.

d