Kor*by KAT Red guts

Hi folks!
Some tasty information for you.
Had an experience to see what is inside of KAT Red mic few days ago.
2K$+ mic. Gearslutz tell me that it should be sweet.
But this sounds like a peace of crap.  Sound like +10db on 7kHz and -10dB on 200Hz. I think something wrong with it. I have an assumption that it fell on the floor.

Schematically it is close to ELA251 or C24.
It use 6111 tube, 10K:600 cinemag output trx and output cap connected after output transformer primary. Same cap configuration I've seen in a couple tube Oktava's. Can anybody tell me more about that cap config?

My quick inspection of mic did not show any problems, all voltages are ok, so may be bad tube or bad capsule.
Inside it is made very well. Good component selection, well layout, so it should sound good.

Link for an images:
https://yadi.sk/d/rxLxmewg3aUtia

Schematic attached.

Does anybody know whose CK12 capsule is it?

dirty1_1garry said:

It use 6111 tube, 10K:600 cinemag output trx and output cap connected after output transformer primary. Same cap configuration I've seen in a couple tube Oktava's. Can anybody tell me more about that cap config?

Click to expand...

There is no "before" or "after" (the transformer) for the capacitor in this circuit. It makes no difference if the capacitor is on the plate or ground side of the transformer. This is totally the same for the current. AFAIK, this applies to AC and DC.

dirty1_1garry said:

Does anybody know whose CK12 capsule is it?

Click to expand...

As far as i know, they make their own capsules. Korby was started by Tracy Korby and Shannon Rhoades, maybe contact Shannon at micrehab.com. He could probably help.

rock soderstrom said:

There is no "before" or "after" (the transformer) for the capacitor in this circuit. It makes no difference if the capacitor is on the plate or ground side of the transformer. This is totally the same for the current. AFAIK, this applies to AC and DC.

Click to expand...

Yes, you are right. Electrically no difference as capacitor block current flow.  I mean may be a little sound advantage when signal reach transformer primary "before"? Or I'm delusional?)

wlinart said:

As far as i know, they make their own capsules. Korby was started by Tracy Korby and Shannon Rhoades, maybe contact Shannon at micrehab.com. He could probably help.

Click to expand...

Tnks!

If the backplates are brass without not acrylic or other plastic, then i can speculate that this is just another edge terminated k67.
But i don't know these capsules at all, see it first time.
4:1 voltage ratio of transformer? Then i would run the tube both half in parallel.
True cardioid input wiring would be better with smaller grid resistor 100-300M.

dirty1_1garry said:

Yes, you are right. Electrically no difference as capacitor block current flow.  I mean may be a little sound advantage when signal reach transformer primary "before"? Or I'm delusional?)

Click to expand...

No, I don´t think so. 

The capsule must be something special, if they sell this microphone for 2K$+! 
Electronics is the absolute minimum, couldn't be simpler than that.

Tim Campbell's CT12 capsule i have has also peak at about 7k, and if it's anything like elam251 it should have low end roll off.

Could it be you simply dont like this kind of mics?

Wow, I see that there is a red LED inside the headbasket!
(Makes a microphone look sooooo cheap!)

RuudNL said:

Wow, I see that there is a red LED inside the headbasket!
(Makes a microphone look sooooo cheap!)

Click to expand...

+1

This would be my first mod - Kill the LED!

Yeah, LED is horrible... Like cheap USB microphones.
Anyway 2k$ for custom made (read non imported from China) capsule and body it isn't so much these days. In this price range still common is chinese rebranded stuff, esepcialy "US made".
7k peak isn't unusual, but there's a question about rolloff, because this can be really made different way and gives different sound effect. It doesn't looks like the circuit have  that much drop - so what? Not matched transformer and impedance cause the rolloff? ...or capsule itself ? If the last one, then not good.

Rudolph - it could be even more simple and probably it could be even better

OK, you could omit a capacitor and a resistor...

ln76d said:

If the backplates are brass without not acrylic or other plastic, then i can speculate that this is just another edge terminated k67.

Click to expand...

I can not tell is it a good/not good copy, but this is CK12 capsule for sure.

kingkorg said:

Could it be you simply dont like this kind of mics?

Click to expand...

may be but... no body like it)
mic owner sad that he tried dozen of times put it as a vocal mic and all times it didn't work so last 1.5year it didn't used.

RuudNL said:

Wow, I see that there is a red LED inside the headbasket!
(Makes a microphone look sooooo cheap!)

Click to expand...

Yes, yes, yes! cheap trick!!

I have found the C12 (and a good number of tube LDC's) are extremely unforgiving of microphone placement, especially in untreated or undertreated rooms.

The ELA M251 plate cap is a good way to tame down the high-frequency response if sized correctly (in the 330pF to 470pF range), and casts the response to be more 'Neumann-esque',  however it also takes one of the strengths way from the C12 design as well.