MK47 as side microphone in MS (mid-side) recording

Can the MK47 in omni mode be used as **side** microphone in MS (mid-side) recording?

More in detail:

The side mic in mid-side recording has to be figure 8.

The MK47 is a clone of the U47. The U47 is like the U48, with one variation: the U47 is omni while the U48 has figure 8 capability. In practice, in the U47 the two sides of the capsule are polarized in the same polarity, and an omnidirectional effect is achieved. On the other hand, in the U48 the capsules are polarized in opposite polarity and a bidirectional or figure 8 pattern is created.

My question is: is there some kind of trick that allows to use the MK47, even if it is omni and not figure 8, as side mic in mid-side recording?

One can be either cardioid or omni.
But the other has to be figure eight.

MK47 can be rebuilt to 48.
Even then it will likely not be precise enough and for the MS trick.

Micaddict: i don't really understand your last sentence, could you clarify please?
Are you suggesting that a couple ( of clone) U47 and U48 wont be precise enough for MS? If so could you explain why you think that?
In fact with real one (neumann u47/48) i ve already done that and was pleased with results. From my experience ms couple are forgiving as long as you have a figure of 8 for side.

It work quite well even with totaly different mic (m130 and 414 i have already done too and results was quite ok).

OK, "likely" may have been too strong there. 

U48 wouldn't be my first choice for that task, though. (if I had other options).
For starters, for best results I'd say the front and back membrane should be closely matched which is not always the case with single backplate capsules. Neumann put some extra effort in the capsules for the M49.
Don'tknow what's in his MK47.
The proof is in the pudding, though, and if it's a tasty one, I'm fully willing to eat my words with it. 

But regardless, that MK47 would have to be rebuilt and there are simpler ways.
That's my main point.



.

Micaddict, thanks,
your explanation make sense and i agree.
About the (orriginal) 48 in figure of 8 you can have great results as  blumlein too in my experience.
I think that theses mic have been used so much for voice that we ve lost of view that initially these mic wasn't designed to be used in close proximity but as middle/far field.
This is true for 47 and 48.

Anyway drgrateful, if you want figure of 8 you'll have to modify capsule biasing as already stated: if i remember correctly you must lower the front membrane +63v of u47 to + 52,5v for a u48 ( you'll have to change r9 and r10 to 3m fo both and connect back membrane through 150m\0.01uf\150m to b+ 105v ). Check the value on original u48 schematic.

There is no possible tricks to make an omni to figure of 8 other than that.

OK, many thanks for the info! That's what I wanted to know.

A small correction to what KrIVIUM2323 wrote:

First of all, look at the U48 schematic. You can Google “U48 schematic”.

The front membrane in a U47/U48 is at zero volts (it’s connected via a resistor to ground).
The backplate should be at half of the B+ voltage, 52.5 Volts.
The back membrane should be at full B+ voltage, 105 Volts.

That means that the voltage on the back membrane is positive (higher) compared to the backplate and the voltage on the front membrane is negative (lower) compared to the backplate.

Therefore, the signals generated from the same sound will be of opposite phase in the back and front membranes.
That is, a figure of 8 configuration.

You are right Stelin,
obviously, this is the backplate which is biased, not the front diaphragm!
It could be done but the diaphragm would attract too much dirt, so it's better to have the backplate polarized. I think this could change the sound too but it's been a while since i've tryed it...
Will do in near future.

Somwhere in the MK47 build thread, Max described the procedure.
FWIW

Yes, KrIVIUM2323, you are right.

It's best to have the "singing side" of the capsule at zero volts. Any high voltage on the (front) membrane will attract dust and debris.