Balanced output

Balanced output on a MCI jh24.

What’s the purpose of R28 (500ohm trim pot) in the feedback loop of ic200.  Just to match it to the Hi side?
What would that look like on a scope? Offset or some kind of asymmetric clipping?

Thanks!

Pretty sure that's for the ability to match the gains of the two opamps as closely as possible. Not 100% sure if and how much that affects CMRR, but i guess it's at least for "extra style points".

Further reading: https://sound-au.com/articles/balanced-2.htm

"For example "Each conductor is always equal in voltage but opposite in polarity to the other. The circuit that receives this signal in the mixer is called a differential amplifier and this opposing polarity of the conductors is essential for its operation." [ 3 ]. This, like many explanations in print (some in otherwise respectable books), describes signal symmetry - "equal in voltage but opposite in polarity" - but fails to even mention the single most important feature of a balanced interface.

SIGNAL SYMMETRY HAS ABSOLUTELY NOTHING TO DO WITH NOISE REJECTION - IMPEDANCE IS WHAT MATTERS!"

Awesome thanks. So is this something to calibrate via scope? If so how?

The gain for the positive side and negative side needs to be the same for a later differential stage to properly cancel CM noise.

JR

Does it, though?

JohnRoberts said:

The gain for the positive side and negative side needs to be the same for a later differential stage to properly cancel CM noise.

JR

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