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Howdy,
I'm interested in building myself a M/S matrix and the electrical version seems to be just what I'm thinking: line level, and works both ways - ms to L&R and L&R to sum and diff.
Is it transformer based (passive) or an active circuit with or without transformers) ? Does anyone else have a good design they'd be willing to share or comment on? I've investigated the Jensen schematics and the Paia circuit I'd just like to see what else is out there.

Thanks,
tim

I've been looking for a decent m-s matrix for some time now and have also considered building one myself.
I too have not found a decent schematic.
AEA makes a fairly cheap m-s matric (http://www.wesdooley.com/aea/MS_Stereo.html), called mark II.
I'd like to know about some other reasonably priced units, though.


Thx,

Cstof

Tim,

this page hase a few schematics and good explanation of the circuit.
http://www.uneeda-audio.com/ms-mat.htm

cheers,

cstof

Hey sorry for not replying to this. I missed it somehow. Our decoder is made up of low noise op amps. We didn't use any transformers, but we do have balanced input and output drivers. Currently there is no output left/right trim, but I'm planning to do that next.

greg,

which of these schematics should i use?
http://www.uneeda-audio.com/ms-mat.htm
Should i use the 'deluxe ms-decoder' circuit? (ms-mat03)
and
Wich Op-Amps should i look for?

thx,

cstof

The deluxe one would be better, but getting a high quality ganged pot could be a hang up. I'll post our schematic when I scan it. Give me a day or so.

Here you go, sorry for the delay. This was made by the last tech who worked here.
Old guy
There should be diodes on the 7818 and 7918 regulators going from input to output so that the voltage on the input is always greater than the output.

greg,

which way should the regulator be wired.

and is that a 15v per side center tapped transformer?

ben adrian

which way should the regulator be wired.

I'm not sure what you mean. There are three terminals on those regulators, input (unregulated V), ground reference (tied to Ground), and out/put (regulated V). It is drawn that way because that is the pin orientation of those chips.

is that a 15v per side center tapped transformer?

Yes. When rectified and filtered you have around 20-22 VDC to work with. This circuit doesn't draw much current so there isn't any sag.

Thanks so much Greg for posting these schematics for us. They're great projects.

A few questions:

Pardon my inexperience with schematics Greg, but what exactly is going on with the symbols that look, to me, like additional pots. I see the 2 "main" Mid and Side 50k pots but what are the 2 10k pots and additional 5 50k pots? Are they internal trimmers? If so, how are they set? I see 4 pots on the front panel of your finished product. That leaves 5 pots unaccounted for.

Also, what kind of diodes should we use to implement your suggestion of attaching some to the regulators? How should they attach?

Finally, where can we get some of those neat metal Electrical Audio symbols to add to the front, giving credit where credit is due?

Thanks Greg.