Mid Side M-S Matrix Uses No Precision Resistors

[mcfarlane.audio]

ive been lurking on this topic for a while, its very very cool and i will definetly be in for a couple of boards one this hits production,

thanks so much for this

[mediatechnology]

Thanks for joining us Brock!

I just got the test run with silkscreen and solder mask. Great work Roger!



We rotated the insert connectors 90 degrees. I've dry-fitted the Phoenix connectors to check the mechanicals.

After I've built this one we should be ready for production.

[MikoKensington]

That is most exciting news.

[mediatechnology]

Thanks Miko!

Got it built. Now for some electrical tests...

[mediatechnology]

Guys -

Roger did a great job on the layout. I'm ordering boards today with delivery expected in about two weeks. I'll be sure to announce when they become available.

MS boards can be ordered from this web page by sending an e-mail:

http://www.ka-electronics.com

There will be plenty of boards available so please wait for an announcement before sending funds or contacting me to enter orders. Questions can be directed to salesATpicocompressorDOTcom

Postage rates are going up May 11th. For board orders they are currently $4.80 for US destinations and $12.30 for most (not all) international orders. For board plus IC orders the fees are currently $6.95 US and $25.71 International. The postage rates after May 11th are not yet known.

[Gold]

I just ordered some boards. Get 'em while they're hot gentlemen.

[mediatechnology]

Thanks Paul!

Yes, they're in. Note that postage is going up Mother's Day and all rate bets are off.

I hope to have an early BOM posted here soon and there are those schematics to get drawn for Roger to tidy up.

Here's the link: http://www.ka-electronics.com/kaelectro ... Matrix.htm

Rather than putting an e-mail address here for the spam bots there's a javascript on the web page that renders a mailto: for ordering. Since I began to use a javascript e-mail disgronificator I went from 100's of spams to 1-2 per day. I call that progress.

[mediatechnology]

I just wanted to thank everyone who has ordered boards recently!

Wayne

[mediatechnology]

I've gotten a little behind on creating and posting documentation. Wayne is stretched thin.

I've cloned this post in the Build Subforum. We might want to discuss build questions here:
viewtopic.php?f=7&t=262

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:


Large format file: https://www.ka-electronics.com/Images/g ... _large.GIF

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



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.



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.



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


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.

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 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.

[bendymusic]

Got my kit, thanks for posting the build infos!! Couple questions though, is there a schematic? Also you mentioned that you put in C2, C3, C18 and C19, does that also mean you put in C5, C6, C21 and C22? Thanks, can't wait to put this together!

&e