Mid Side M-S Matrix Construction Information

Our build thread for DIY projects, including the MS Mid Side Matrix.

Mid Side M-S Matrix Construction Information

Postby mediatechnology » Fri May 08, 2009 9:51 pm

This is a clone of the post in the original thread. We might want to put build questions in this thread.

The PC Board and other items may be purchased from Etsy: viewtopic.php?f=1&t=725

Update 5/12/2015:

PDF Assembly Instructions are here: http://www.ka-electronics.com/images/pd ... ctions.pdf

Added Mouser Project Manager bill of materials for the Precision MS Matrix.
These lists are not editable but you can "order" the project to move it to your shopping cart, then save the cart as a project to allow editing.

There are two lists one with, and one without, THAT ICs.
I chose an LME49860 for the 5532 location.
There are no bridge rectfiers on the BOM for phantom protection: Most people don't use them.


Without THAT ICs http://www.mouser.com/ProjectManager/Pr ... 96947b82d5 (material cost as of 9/2/2013 in USD $37.68)

With THAT ICs http://www.mouser.com/ProjectManager/Pr ... 246710b37f (material cost as of 9/2/2013 in USD $81.88)


Image

Here's a preliminary bill of materials:

13) 8 pin sockets
4) THAT1246 IC1, IC2, IC7, IC8
4) THAT1240 IC3, IC4, IC10, IC11
1) NE5532 IC9
4) THAT1646 IC5, IC6, IC12, IC13
9) 3 pin Phoenix terminal blocks Mouser 651-1725669 (Or 10 if you want a ground tie block)
14) 0.1/100V Mono Ceramic Mouser 581-SR201C104KAR (There are spots for a lot more but 14 are enough)
I stuffed C2, C3, C13-16, C18, C19, C24, C25, C32-35
2) 1R 1/4W R1 and R2(Flameproof/fusible is better but generic carbon film if that's all that's available)
2) 1N4004 D1, D2
8) 10uf radial NP or polarized 25V or greater C38-41, C42-45
2) 47uF/35V C36, C37
2) 22pF/100V Mouser 581-SR151A220JAATR1, C46, C47
2) 10K 1% Mouser 271-10K-RC, R3, R6
2) 20K 1% Mouser 271-20K-RC, R4, R5
4) DB-104 Bridge (optional for phantom power protection) BR1-4
8) 0.1" 2 Pin headers with jumper clips (To bypass various inserts at BR, BL, CS, CM, FS, FM, GR, GL)

Power Supply requirements:

+/-15V to +/-18V at ~ 40 mA. I recommend 18V rails as it buys you slightly more headroom in the Encoder Mid channel.

This is a stuffing guide:

Image
Large format file: http://www.ka-electronics.com/Images/gi ... _large.GIF

The flow diagram. Note that points B, C, F and G correspond to the header connections.

Image

Note that the Encoder and Decoder are interchangeable. For highest accuracy I recommend that the left side be used as the Encoder and the silkscreen is marked that way. For -6dB encoding, the decoder side can be used but it's far less accurate since the 1% MF resistors of the -6dB stage are in the Mid/Side Domain where they affect crosstalk. When the -6dB stage is used in the decoder, the accuracy of the resistors are far less critical since the only affect channel balance by a very small amount.

A photo might help too. Note that D1 is installed backwards in the photo. Both really point to the right and the PCB silkscreen is correct. Trust me.

Image

Note that the 5532 -6dB gain stage, in the L and R domain, sits after the 1240 decoder between it and the 1646.

This is the schematic for the 1240 encoder and decoder IC3 and IC4, IC10 and IC11.

Image

The 1246 Input stages look like this. I stole this from the Pico Compressor drawings. Ignore the component designators.

Image
Image stolen from the Pico Compressor Stereo Edition

The 1646 OutSmarts(tm) stages look like this. Ignore the input coupling caps. They are not used and the component designators are bogus.

Image If you're going to use the 1646 with single-ended loads make sure the other output is grounded or it will seem noisy.

Image
Image stolen from the Pico Compressor Stereo Edition

This is the 6dB pad in the decoder. One-half shown. That bit about the compensation capacitor being optional I wouldn't take too seriously. Use a 22pF with a 5532.

Want to use a different op amp? Be my guest. I'd keep it bipolar and low noise. This is not the place for a TL072.

Image
Last edited by mediatechnology on Fri Apr 08, 2016 2:16 pm, edited 15 times in total.
Reason: Because I felt like it.
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Re: Mid Side M-S Matrix Construction Information

Postby emrr » Sat May 09, 2009 8:05 pm

Thanks. Can't wait to find the time to order and build!
Best,

Doug Williams
Electromagnetic Radiation Recorders
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Re: Mid Side M-S Matrix Construction Information

Postby Gold » Sun May 10, 2009 1:38 pm

What is the orientation of the jumpers on the board? To disable the insert point is the jumper installed from one silkscreened box to the box below?
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Re: Mid Side M-S Matrix Construction Information

Postby mediatechnology » Sun May 10, 2009 1:50 pm

Image

EDIT: If I understand your question correctly, no. Take a look above. The bottom-most rows are Ground. The jumpers link vertically from insert send to insert return. To disable them just remove the jumper or store it on one pin.

Look at BL and BR for example. That's point B on the block diagram for Left and Right.

Image

The top row of pads on BL are the Left Insert Send Out.
The middle row of pads on BL are Left Insert In. (It leaves the picture to the right.)
(There are two sets of pads for each input and output.)

Point B is Encode Left and Right Out Post-Line Receiver.
Point C is Encode MS Out.
Point F is Decode MS Out Post-Line Receiver. (Single-ended Decode Input or location for buffered MS ratio trims.)
Point G is Decode Left and Right Out Pre -6dB Active Attenuator and Line Driver.

The "Precision" bypass mode jumps from C insert send to F insert return.
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Re: Mid Side M-S Matrix Construction Information

Postby Gold » Mon May 11, 2009 3:32 pm

Does the square pad indicate + for the electrolytic caps?
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Re: Mid Side M-S Matrix Construction Information

Postby mediatechnology » Mon May 11, 2009 4:21 pm

Gold wrote:Does the square pad indicate + for the electrolytic caps?


Yes, square = positive.
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Re: Mid Side M-S Matrix Construction Information

Postby Gold » Mon May 18, 2009 7:21 pm

I got the encode stuffed and powered up over the weekend with no problems. I'll integrate it with the monitor controller soon. I don't think I'll get around to a full build for a while.
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Re: Mid Side M-S Matrix Construction Information

Postby mediatechnology » Mon May 18, 2009 7:44 pm

Cool Paul thanks.

The single encoder you built can also be a decoder if you re-label input left and right mid and side. The mid and side ouputs then become left and right out. So what you have right now can do both if you want to run decode experiments.

This is the "half-duplex" build. :D
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Re: Mid Side M-S Matrix Construction Information

Postby Gold » Tue May 19, 2009 7:18 pm

I'm a bit of a simplex anyway.
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