Mid/Side encoder, splitter? Any project, schematics?

[aomahana]

Hi,

I have a spare Wayne Kirkwood MS Matrix pcb and associated THAT IC's.

This one ....
http://www.ka-electronics.com/kaelectronics/MS_Matrix/MS_Matrix.htm

If you want to buy it, PM me.


All the best,
aomahana.

 

[BGroen]

Did anyone try the 4 resistor passive scheme? Lossy?
Is grounding at M(+) correct?

 

[RuudNL]

Years ago I have built a M-S encoder/decoder, with fixed/variable M and S level (based on the work of Wayne Kirkwood) , an Elliptic Eq with variable frequencies, Solo and mute for M and S, combined with a low-cut and high-cut filter and a 'brick wall' 15 KHz filter. (Especially for vinyl.) There are also inserts for the M and S channels.

 

[telewulf]

Did anyone try the 4 resistor passive scheme? Lossy?
Is grounding at M(+) correct?

I asume you refer to the 8 resistor passive scheme by 5v333, right?

Well no, I haven´t because I was never much into vinyl, never liked coincidential microphones and was never working on stereo-FM-transmitters - and that are the only fields known to me, where MS applies.

But if I may drop in my thoughts on passive audio appliences: At first glance they look simple and thus very inviting but really it´s quite the opposite. The impedances of the driving source as well as the load come into the equation and so you must not take these 8 resistors on their own and expect a brilliant result. In order to decouple them from their surroundings, you need buffer amps before and after the matrix.
Are you familiar with op amps, say NE5534 and such like? If not, then google "tutorial op amp buffer".

best wishes from Bremen,
Wulf

 

[BGroen]

I meant this one from Neumann.

Yes I could buffer them, but I also like a passive box that wouldn't need power. And I was curious for this one.

 

[emrr]

I’ve built a number of transformer matrixes for MS, I usually track through them to print stereo. I added a passive split in front of one to be able to print either/both. Wayne’s kits are cool too.

 

[MidnightArrakis]

Years ago I have built a M-S encoder/decoder, with fixed/variable M and S level (based on the work of Wayne Kirkwood) , an Elliptic Eq with variable frequencies, Solo and mute for M and S, combined with a low-cut and high-cut filter and a 'brick wall' 15 KHz filter. (Especially for vinyl.) There are also inserts for the M and S channels.

• Did you both -- design and build -- this M-S encoder/decoder?
• Or, did you build an already existing M-S encoder/decoder circuit?
• If you -- DID -- design an M-S encoder/decoder circuit, would you happen to still have a complete set of the schematics of it?

/

 

[RuudNL]

would you happen to still have a complete set of the schematics of it?

The schematics are in my head... (In general I never draw schematics for equipment for my own use.)
As mentioned: the M-S encoder and decoder part are based on the schematic of Wayne Kirkwood.

 

[telewulf]

I meant this one from Neumann.

Yes I could buffer them, but I also like a passive box that wouldn't need power. And I was curious for this one.

Right, now I know what you meant, hadn´t seen that one. Amazing what interesting ideas can come out of the good old bridge!

Well in this case M-signal as well as S-signal have to be not only symmetrical but also ground-free-symmetrical signals which you only get out of transformers. So this matrix has to be fed by transformers and not by your average symmetrical output, which really consists of two seperate amp stages on opposing phases. If you would use one of these in this case, the grounding of of M+ would only cut one of them short and thus reduce the M-signal by 6 dB.
As I said: When you use passive appliances, your source and load must be considered.
And speaking of that: Are you sure that your source-transformers can handle a 500 Oms load? That is reeeally low impedance ... and the outputs are asymmetrical and -6 dB and at a souce impedance of 250 Ohms and at 180 degrees phase ... well ... if you insist ... I´d say passive doesn´t look all that good to me in this case.

Interesting though!

 

[MidnightArrakis]

The schematics are in my head... (In general I never draw schematics for equipment for my own use.)
As mentioned: the M-S encoder and decoder part are based on the schematic of Wayne Kirkwood.

[I never draw schematics for equipment for my own use] -- OK, well.....if you can at least draw a schematic on paper and scan it into a PDF file, I will recreate your schematic in either CADENCE/OrCAD or KiCAD and send it back to you. Sound like a plan???

[The schematics are in my head] -- Or.....just ship to me your brain and then I can use some highly-advanced alien-technology to extract your "mentally-embedded" schematic and create a CAD-drawing out of the data!!! Wouldn't -- THAT -- be really cool???.....

[As mentioned: the M-S encoder and decoder part are based on the schematic of Wayne Kirkwood] -- I am not familiar with either this person or his design work, but I do have a ROYER SF-12 Ribbon Stereo Microphone that I use for "LIVE" stereo recordings.

/

 

[gyraf]

I meant this one from Neumann.

Yes I could buffer them, but I also like a passive box that wouldn't need power. And I was curious for this one.

For that one, you'll need fully floating, fully balanced signals at both inputs - use good isolation transformers for both inputs. Your output will be unbalanced, referring to the common ground.

/Jakob E.

 

[BGroen]

Aaah thanks Gyraf and Telewulf for the info. If I need transformer anyway I'll go for the transformer matrix suitable for line in/out so I can use my hardware without any loading issues. I found some posts on this already and I will Figure it out.

As a try-out I will build this Neumann circuit, because as I understand it I can connect mics directly which can be of use. It's only 4 resistors.....

 

[emrr]

As a try-out I will build this Neumann circuit, because as I understand it I can connect mics directly which can be of use. It's only 4 resistors.....

The problem with that is the matching load on the mics.

 

[BGroen]

The problem with that is the matching load on the mics.

Meaning I should measure and match resistor values as closely as possible and to match output impedences of the mics?

If I would use two same mics with output transformers would work I guess? How is the output impedence tolerance of dynamic mics?

 

[emrr]

Meaning I should measure and match resistor values as closely as possible and to match output impedences of the mics?

If I would use two same mics with output transformers would work I guess? How is the output impedence tolerance of dynamic mics?

No, you bridge mics, you don’t match them.