Mid Side M-S Matrix Construction Information

Construction information for DIY projects, including the MS Mid Side Matrix, Elliptic Equalizer, Mastering Console, Phono Transfer System, Insert Switcher and the Dual Class-A Amplifier. You can post your baby pictures here.
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mediatechnology
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Re: Mid Side M-S Matrix Construction Information

Post by mediatechnology » Tue May 14, 2019 5:52 pm

Thanks Doug.
It is useful but what I'm not fond about is the anemic Side being attenuated another 6 dB.
Out of several hundred units sold I've only been asked for it twice.
For those situations its a good work-around.

The MSII however allows both Mid and Side to be offset at the insert with Mid -6dB and Side +6 with the gain correction automatically applied on decode.

Gold
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Re: Mid Side M-S Matrix Construction Information

Post by Gold » Wed May 15, 2019 10:07 am

I took another look at the MSII. I have a pile of the original MS boards so I didn’t look to closely at this.

The switching options are fantastic. I’ve been trying to cobble together what this does with the original boards for my monitor controller. This takes care of all the options I want. Then there is the tilt and widener to boot. Nice!

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mediatechnology
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Re: Mid Side M-S Matrix Construction Information

Post by mediatechnology » Wed May 15, 2019 5:18 pm

Thanks Paul!
The MSII added what people usually did with their original MS boards.
I'm about to place an order for more MSII boards which sell out as fast as I get them.
I've been chronically out of stock on those since introducing them a year ago.

The original board is ideal for simple MS encoding/decoding and Mid/Side monitoring.
I'm not sure I'm going to make any more of the original MS but I may do one optimized for Mid/Side monitoring that will run on a single 9V supply or bipolar 15V.
I've sold several for performance applications to guitarists who desperately need 9V operation.

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Re: Mid Side M-S Matrix Construction Information

Post by Gold » Thu Oct 29, 2020 1:40 pm

I am using the first generation M/S board as a Line Receiver and Line Driver as well as M/S matrix for my Barry Porter EQ build. It will be M/S only. The BP has a balanced line receiver feeding a unity gain non inverting opamp buffer feeding the summing amp in a SVF topology. The input impedance of the the unity gain buffer is 5K.

Will the output of U3/U4 drive that well? I know under normal circumstances the 1240 would but it is being used in a non standard manner so I thought I would check.

The output of the BP EQ has a balancing stage but I can pick off the unbalanced signal before that. I would like to feed U10/U11 with this unbalanced signal. As long as there is no build out resistor at the output is that okay?

If I am able to do everything above then the level through the EQ is -6dB assuming a 1246 input. This makes the U9 gain stage unnecessary. Can I feed the output of U10/U11 directly to U12/U13 1646?

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mediatechnology
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Re: Mid Side M-S Matrix Construction Information

Post by mediatechnology » Thu Oct 29, 2020 2:14 pm

Gold wrote:
Thu Oct 29, 2020 1:40 pm
I am using the first generation M/S board as a Line Receiver and Line Driver as well as M/S matrix for my Barry Porter EQ build. It will be M/S only. The BP has a balanced line receiver feeding a unity gain non inverting opamp buffer feeding the summing amp in a SVF topology. The input impedance of the the unity gain buffer is 5K.

Will the output of U3/U4 drive that well? I know under normal circumstances the 1240 would but it is being used in a non standard manner so I thought I would check.

The output of the BP EQ has a balancing stage but I can pick off the unbalanced signal before that. I would like to feed U10/U11 with this unbalanced signal. As long as there is no build out resistor at the output is that okay?

If I am able to do everything above then the level through the EQ is -6dB assuming a 1246 input. This makes the U9 gain stage unnecessary. Can I feed the output of U10/U11 directly to U12/U13 1646?
Paul -

You can do all three items.

U3/U4 (THAT1240) will drive 2KΩ to +21 dBu so you should be fine driving the BP input from the MS encoder pre-THAT1646 at inserts CM and CS.

The BP outputs can drive the MS decoder, U10/U11, directly as long as the source impedance is 0Ω. So yes to your second question.

U10/U11 can drive the 1646 pin 4 directly.

Let us know how the MS Barry Porter EQ works out.

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Re: Mid Side M-S Matrix Construction Information

Post by Gold » Thu Oct 29, 2020 2:43 pm

mediatechnology wrote:
Thu Oct 29, 2020 2:14 pm


You can do all three items.


Let us know how the MS Barry Porter EQ works out.
Thanks Wayne. Will do. I had the M/S board working in the two channel version I built but I was using all the sections. I thought it would be better to eliminate as much as possible. The sound before was good but maybe this will be a little better? I wasn't happy with the switch wiring in the first unit. It left some exposed shield wires which could short to something. I figured I leave the working two channel version, work on a four channel version and circle back to complete the first try. I'm glad I did because I think I can fix it without starting from scratch. Wiring all the switches takes over 40 hours...

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mediatechnology
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Re: Mid Side M-S Matrix Construction Information

Post by mediatechnology » Thu Oct 29, 2020 3:16 pm

By integrating it the way propose you're eliminating a lot of gain stages both on the MS and the BP EQ.
Sometimes less is more.
The signal path will be a lot shorter.

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Re: Mid Side M-S Matrix Construction Information

Post by Gold » Sat Jan 16, 2021 2:59 pm

Here is one of the two units four channel Barry Porter EQ builds. It is M/S only using the first generation M/S boards. It's not totally the fine build but I have it installed in the console now. I had a chemical mishap with some aluminum brightener that damaged four of the eight boards. This unit uses the four damaged boards. I wanted to see if I could use them. It took a while to get solder to stick to them but I eventually was able to. There were broken traces on all four boards that I had to work through. There was a short in the high mid section of one of the boards that couldn't be worked around. Three of the four damaged boards I was able to get going. I have the one with the bad section on a Preview channel now. I have located a pair of boards I can buy. I'll only be using two of the damaged boards and I'll keep them on preview channels.

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The M/S boards are mounted in the back. I tried doing what I proposed in the post above. Skipping a bunch of amplifier stages. After tearing my hair out for days I eventually figured out the 1246 couldn't drive the SVF EQ section. I needed to go through the EQ in L/R mode because trying to do it in M/S is very confusing and just not a good way to do it. I ended up using the board as intended with all the sections. I also have terminal blocks and jumpers installed so I can with it to L/R mode for testing and repair.

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This completes the processing units for the console. Two EQ's and two compressors. I have to finish the second BPEQ. I have to do some more work on the meters and monitor. Finish the Crossfader and replace the LPF/HPF I have. Then It's done.

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Re: Mid Side M-S Matrix Construction Information

Post by mediatechnology » Sat Jan 16, 2021 5:23 pm

Nice!

Did you CNC those dimples with one of your tools or did you have someone else do it?

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Re: Mid Side M-S Matrix Construction Information

Post by Gold » Sat Jan 16, 2021 6:22 pm

mediatechnology wrote:
Sat Jan 16, 2021 5:23 pm
Nice!

Did you CNC those dimples with one of your tools or did you have someone else do it?
Do you mean the marks? That is all hand done. I had templates made for the dots and used hand stamps for the text.

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Dot templates and layout.

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Hand stamps and holders.

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