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[Shipping] Euro DIY Mid/Side Encoder/Decoder PCB/panel
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3, 4, 5, 6, 7  Next [all]

I would be interested in:
Through-hole PCB
 62%  [ 43 ]
 37%  [ 26 ]
Total Votes : 69

Author [Shipping] Euro DIY Mid/Side Encoder/Decoder PCB/panel
Stab Frenzy
I've been interested in making a Mid/Side encoder/decoder for my Euro system for a while now so have designed a board for it.

edit: New rev PCBs have 3.2mm mounting holes for 4U and 5U use, footprint for shrouded power header and bigger holes for fitting a wider variety of resistor sizes.

edit: New black and gold panels available! The circuit PCB is unchanged. If you're after an original red panel they are still available at ModularAddict and Synthcube.

Video of what happens when you modulate the stereo width at audio rates:

Demo video: Full details of what's going on are on the youtube page, but basically there are two filters processing the mid and side separately and the joystick is increasing the width of the panning. Note that because of the way that Mid Side stuff works you're not going to get the full (or any) effect if you listen to this in mono. Headphones or monitors are recommended.

Another video using it to process a drum loop:

This is a fairly simple circuit but that said I'm just selling the boards, I'm not offering any guarantee of support or troubleshooting if your build doesn't work. It's not intended as a beginner project so if you've never soldered before maybe start off with something fully documented and supported first. thumbs up

After reading through the recent thread on including schematics for projects I've decided to offer up the schematic for this. I didn't lay it out thinking anyone but me would ever see it so apologies if it's messy or unclear.

A bit of theory on how it works:

Each of the inputs has an opamp buffer with a gain of -1. (U1 + U3)
The inverted and buffered signals are then sent to the mixing stages (U2 + U4) where they're mixed like so:
M out = (L + R)/2
S out = (L - R)/2
L out = M + S
R out = M - S
As both the input buffers and the mix stages are inverted the signal comes out with the correct polarity.
Gain of the mix stages is given by the ratio of the input and feedback resistors, for example on the M out stage (U2.1) the input resistors are R7 and R9 (10k) and feedback is the resistance formed by the two resistors in parallel R23 and R24 [10k//10k = 5k]
5k/10k = gain of 0.5
The parallel resistors (R23&R24, R25&R26, R27&R28) are used to get a value of 5k with two 10k resistors as 10k resistors are easier and cheaper to come across than 5k, also using all 10k from the same batch should theoretically give you a better match.
If you're aiming for a super-precise result then the sets of resistors to match would be:
R1, R5 - same value
R2, R6 - same value
R3, R11 - same value
R4, R12 - same value
R7, R9, R23, R24 - All the same value
R8, R10, R25, R26, R27, R28 - All the same value
R15, R21, R16 - All the same value
R17, R22, R18, R29 - All the same value
However I got a really precise result without matching.

Interest list below.
Cost is US$30 per set shipped worldwide, US$20 for board only, no panel. Additional sets are US$20/10 with combined postage. Second batch is in so I should have these available for a while. Post here or PM me to be added to the list. Guinness ftw!

Username (PCB quantity) (panel quantity) Red = paid Blue = shipped
spneca (2)(2)

Paranormal Patroler(1)(1)
Stab Frenzy
Editing this for build info.


I'm adding a Mouser cart which I believe is all correct, please double check before you order though: ba743

Notes on the mouser cart:
There are 10 jacks and 10 nuts even though only 8 are needed because due to the price break 10 is cheaper than 8. These jacks are more expensive than the Thonk PJ302M but if you want to get everything in one place and/or you don't need 50 and/or Thonk is out of stock you can get them here. Otherwise delete them from the cart.
There is no power connector because I didn't design this board for a shrouded header, although you should be able to squeeze one in there. I just buy big long IDC headers and snap them off ten pins at a time.


R13, R14, R19, R20 - 1k
All other resistors 10k (25x)
to keep the module 50mm deep I've used a small resistor footprint. I used Multicomp MF12 series resistors which are widely available if you don't have anything that fits on hand. Any 1/8W resistor should fit.

C1, C2 - 22uF or 47uF
C5, C6, C7, C8 - 22pF
unmarked ceramics - 0.1uF
L1, L2 - Ferrite bead, I used whichever ones I had lying around, not sure of the value. Can substitute a 10 Ohm resistor here
F1, F2 - PTC fuse, 100mA hold 200mA trip
D1, D2 - 1N4001
ICs are NE5532s but other op amps with the same pinout should work in theory.
Sockets are PJ302M from Thonk

Most of those should be things you have lying around in parts drawers, nothing terribly exotic here.
I missed this! I'm in for 2.
Interested. How many HP?
Stab Frenzy
Cool, I'll edit the first post with an interest list. Will post pics and prices once I've confirmed the PCBs are go.

It's 4HP; L in, R in, M out, S out, M in, S in, L out, R out. M out is half-normalled to M in, same with S out to S in. That way you can AB any processing just by pulling the jack on the input. PCB mounts perpendicular to the panel so finished module will be 50mm deep.

There will be PCB panels available, artwork is below: PCB panel will have white silkscreen on red soldermask.

what does it do? i really dont have a clue what it is
I just looked up what it does - I see why it might be useful/interesting when mixing, but surely when using modular it's more flexible to record elements separately and mix later? Maybe I'm missing some wicked new technique or something! cool
Stab Frenzy
It processes a stereo signal so that you can effect or process just the mono portion of the stereo signal, or just the sides. It's a process that's used a lot in mastering, for example to high pass filter the sides without touching the centre, but can be used in a lot more creative ways like compressing mid and sides separately so the compression is true stereo but doesn't shift the stereo image centre, to adding distortion to just the sides, running through two different filters without skewing the stereo symmetry. Anything processed as M/S will come out as a mirror image in a way, if that makes sense.

You can do other things like dynamically LPF the centre and HPF the sides, controlled by the same LFO, which can get pretty wild. As I mentioned above it can also be used as a CV processor, giving the analogue average and the difference between two voltages, so if you fed it -2V and +4V you'd get 1V out the mid output and -6V out the side output. You can process CV sources in some cool ways like this, as the voltages obviously change dynamically as the inputs vary.

Once I've got the boards I'll record some demos and post them here.
I would like to buy 2 sets, but how much will it cost?
Voted for SMD but Through-hole PCB is also fine.

Guinness ftw!
I'm interested in one PCB, no panel needed.
I'd like panels with mine, please.
Stab Frenzy
Thanks guys, updated the original post with quantities. The price will probably be US$10 per board and US$15 per panel, I may be able to bring that down after I see the PCBs though, I'd like to. Postage will be US$5-10 worldwide. (I'm in Australia)
Wow. First time I've seen anything like this in the modular realm and totally interested. If by chance the price drops I may be interested in two sets but for now I'm in for one board and panel.
Stab Frenzy
PCBs have arrived, will build one up this week to check for errors and then post some audio examples and contact everyone who's expressed interest. Guinness ftw!
Stab Frenzy
An update: Built one up and the channel crosstalk is a bit too high for my liking so I'm doing another revision. Sorry for the delay but I want to do this right.
Serious experimenters tool. Please put me on your List for 1 Set of Board + Panel.
interested in two PCBS and two panels.
I like the red panels in the pic
Any news?
m/s encoding is super useful. i would want 2
Stab Frenzy
keninverse wrote:
Any news?

The boards left Hong Kong on the 11th of November but still haven't arrived, I'll update here as soon as they do. Next time I'm not gonna choose the cheap shipping option. d'oh!

Neutron7 wrote:
m/s encoding is super useful. i would want 2

Cool, added you to the list!
Stab Frenzy
Boards were here tonight when I got home! I built one up and it's working well, I'll record some demos soon. Got a good patch going with the mid and side going to two different filters and using the voltage controlled panning of the L-1 mixer to go between just mid and both!

Everyone on the list expect me to be in touch in the next day or two. Guinness ftw!
I'd be interested in a set if you have extras.
Stab Frenzy
Built up my first one and it's working perfectly! Pics added to the first post. Here it is in action:

Looks like there's more interest than I anticipated and I'll need to get some more boards made, I've contacted people in the order they expressed interest. If I haven't contacted you yet it's because I'm waiting to hear back from people ahead of you/waiting for more front panels.

Guinness ftw!
Stab Frenzy

Did another little demo processing a drum loop that has less shaky camerawork.

All orders that have been paid so far will be shipped this morning. Guinness ftw!
Stab Frenzy
First run are all sold and shipped! I should have more in stock come December 17th barring any production errors, so if you're interested post here or PM me to get on the list. I won't be sending out invoices until they're ready to ship.

Thanks to everyone who's bought these from me so far! I'm looking forward to seeing some completed builds so when you get your boards and build them up be sure to post here! Guinness ftw!
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