Mid Side M-S Matrix Uses No Precision Resistors

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mediatechnology
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Re: Mid Side M-S Matrix Uses No Precision Resistors

Post by mediatechnology » Sun Nov 18, 2018 9:22 pm

Paul - I don't think I've ever seen one measure worse than about -65 dB on a full encode/decode through the inserts.

Here's an experiment you can try to isolate whether its the encoder or decoder:

Parallel the L and R in puts on the encoder so they both see the same signal.
Mid should be +6 relative to either L or R.
Side should be in the mud easily below -60.
Reverse the polarity of R In at the input connector.
Side should be +6; Mid in the mud.

Repeat for the decoder the same process.
Flipping the polarity of Side relative to Mid at the insert return will steer the output from L to R.
https://ka-electronics.com

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Gold
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Re: Mid Side M-S Matrix Uses No Precision Resistors

Post by Gold » Mon Nov 19, 2018 12:41 pm

mediatechnology wrote:
Sun Nov 18, 2018 9:22 pm
Paul - I don't think I've ever seen one measure worse than about -65 dB on a full encode/decode through the inserts.
Just to recap. I have two M/S boards going. One for Preview and another for Modulation. I'm getting -70dB crosstalk on both boards when used as intended. When I reverse the Encode and Decode sections I'm getting -30dB crosstalk on both boards. If I'm supposed to be getting closer to -50dB crosstalk when reversed it's likely either a construction error or an error in the test setup because both boards measure the same.

I'm going to bag this for now. I have things higher up on the list that need attention.

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mediatechnology
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Re: Mid Side M-S Matrix Uses No Precision Resistors

Post by mediatechnology » Mon Nov 19, 2018 6:48 pm

OK if you're getting -70 in the normal encode/decode configuration I doubt there's a construction error.

When they're reversed, the gain error in the adjustable mode is enough to degrade it.
I would add a trim.
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