Mk47 to Supercardioid?

Hi All,
So i've managed to end up with 2-MKU47's and 1- MK47, They are all great mics, the MKU's are better imv, so I was trying to find some info on maybe modding/converting the MK47 to a Supercardioid pattern to more resemble the FET47 pickup and possibly use it for kick drum and other duties begging for more off axis rejection. I know the SPL handling capability of a U47 is significantly less than a FET47, not sure if that would change with an appropriate modification? To be honest, i don't know where to start on this, I searched and came up with no info on what dictates polar patterns in mic circuitry, but i'm interested in learning, i'm guessing it has to do with front to back plate charge? can anyone point me in a direction? or confirm i'm out of my mind.... again... for even contemplating this 

Thanx

Somewhere in the MK47 thread Max explains how to turn the mic into a U48.  Omni then becomes figure eight; cardioid remains. Still, you might not want a figure eight for kick, either. (?) Basically, supercardioid sits somewhere between cardioid and figure eight. I say it should be possible, but you need to ask others how to solve this electronically.
BTW, hypercardioid has the best overal rejection of all patterns. This sits between supercardioid and figure eight.

Oh, and would you be happy if the mic had one pattern only (viz. supercardioid only, like the fet version you mentioned)?

... or take the opposite route and make it multipattern ...

or confirm i'm out of my mind.

Click to expand...

I wouldn't say so. 

Ok, as always i made mistake with these "mk47" and "mk-u47" so schematic is for mk-u47
Still it is valid for both projects.
Supercardioid is truly simple.  Two extra caps  and two resistors.
It's fixed supercrdio, for switch options check my S16 project:
https://groupdiy.com/index.php?topic=62423.0

micaddict said:

Somewhere in the MK47 thread Max explains how to turn the mic into a U48.  Omni then becomes figure eight; cardioid remains. Still, you might not want a figure eight for kick, either. (?) Basically, supercardioid sits somewhere between cardioid and figure eight. I say it should be possible, but you need to ask others how to solve this electronically.
BTW, hypercardioid has the best overal rejection of all patterns. This sits between supercardioid and figure eight.

Oh, and would you be happy if the mic had one pattern only (viz. supercardioid only, like the fet version you mentioned)?

Click to expand...

Thanx micaddict, i'm not sure that hyper is more rejective than super? what does this chart show? Maybe a slightly larger backside pattern offers more side rejection?

ln76d said:

Ok, as always i made mistake with these "mk47" and "mk-u47" so schematic is for mk-u47
Still it is valid for both projects.
Supercardioid is truly simple.  Two extra caps  and two resistors.
It's fixed supercrdio, for switch options check my S16 project:
https://groupdiy.com/index.php?topic=62423.0

Click to expand...

Thanx In76d!
Man, you are a goldmine! I've also followed your lead on the pair of Elam's I'm building almost to the letter, thanx so much for taking the time to scratch that schemo out, much appreciated!

here's another question pertaining to this, since the In76d schemo shows an apparent filtering off of front capsule plate juice to control grid/ground to create the super pattern, does this increase the the SPL handling capability of the mic?

tonycamp said:

Thanx micaddict, i'm not sure that hyper is more rejective than super? what does this chart show? Maybe a slightly larger backside pattern offers more side rejection?

Click to expand...

Thanks for posting that chart. Saves me time looking for one. 

what does this chart show?

Click to expand...

It shows that hypercardioid has the lowest percentage for ambient sound sensitivity and the highest distance factor.
The two are inversely related.

tonycamp said:

here's another question pertaining to this, since the In76d schemo shows an apparent filtering off of front capsule plate juice to control grid/ground to create the super pattern, does this increase the the SPL handling capability of the mic?

Click to expand...

You will get slightly lower level, so the headroom will be higher, and then a little more SPL it can handle.
These are really small diferences, but sometimes it can sounds worse than typical 47 cardioid (depends on capsule, tube, overall circuit).
Definately "pure" cardioid sounds best. and there's hard to make same sounding cardioid with multipattern option.
Tried every combination of input circuit for M-P. There are two options which sounds pretty good, similar to pure cardio - C414 topology (with voltage applied to both diaphragms and signal taken from backplate) or combination of double backplate connections.
First of all i would make switchable pattern for cardio/supercardio and make samples to compare - is it worth to use supercardio?  With dynamic microphones there's definately difference in signal rejection from the sides (but always there's a "tail"), but with many condensers not really - overall microphone sensitivity is really high, so it will pickup all the crosstalks etc. similar way than cardioid.