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Subject: Re: Re(2): [motm] Re: Balanced/Unbalanced - P.S.

From: "J. Larry Hendry" <jlarryh@...>
Date: 2001-02-04

This is great information to have coming from someone that knows something
about it. There is so much information out there, and not all of it good.
I never stopped to think about the difference in impedance of the two
inputs.

Would the 3 op amp solution be an inverting buffer for signal +, a
non-inverting buffer for signal -, and then the third to sum the outputs of
the first two?

Larry

----- Original Message -----
From: <jhaible@...>
To: <motm@yahoogroups.com>
Sent: Sunday, February 04, 2001 1:30 PM
Subject: Re(2): [motm] Re: Balanced/Unbalanced - P.S.


> > If you are careful to match the input resistors can't you get
> > good common mode rejection with active balancing?
>
> No, you can't.

Addition: yes you can, but not with that simple one-opamp
circuit. Three opamps is much better, or even better, discrete
symmetrical frontend and then an opamp, as in (now obsolete)
SSM2017.

JH.