Will Chinese MK-012 capsules work on the Russian preamps?

Do the usual Oktava MK-012s work for the Chinese ones. I knowingly purchased a pair of Chinese Oktava MK-012s because they were super cheap (a pair for the price one new one would've cost me), and came with all the capsules (no pad though), and from what I understand the Chinese ones aren't generally any worse than an authentic one from the time would've been (since the Russian factory had poor quality control).

My question is do they respond to the common circuit mods for the older Russian ones?

Bumping because the preamps are really noisy. Would I be able to use the Chinese capsules with the Russian preamps?

I suppose they will. A capsule is a capsule, isn't it?
The best way to check is to try it... 

RuudNL said:

I suppose they will. A capsule is a capsule, isn't it?
The best way to check is to try it... 

Click to expand...

Apparently the threads are different so it won't attach to the body. I bought a pair of Chinese Oktava MK-012s but the seller made no mention of the extra noise they had, which is this wind sound that exists with all capsules on both mics, so I'm pretty sure it's the preamps. If the Russian preamps and Chinese capsules worked well together I was going to just get a pair of the new Russian pres.

I'm gonna see if I can get a partial refund from the seller, since the mics are in the same functional condition and I just stripped an already stripped screw further. If I can't, if the replacement PCBs online will fit I might try to build one of those.

Wouldn't is be the best solution to modify the amplifier body of the Chinese ones?
(The circuit is pretty simple.)

Pictures of the Chinese PCB and capsule will help.
found this
http://recordinghacks.com/fake-oktava-mk-012-photos/

Attaching pictures of the PCB. It was originally covered in some sort of protective film that clearly degraded over the years, because it flaked off and yellowed like crazy.

And here's the back.

There's a (good?) chance the circuit's actually the same - the components seem to largely match the original, on first sight.

Have you tried the China built preamps in the housing without the capsules to check the noise?
Or better with a Oktava cap pad screwed on without the capsule?

If the preamps are noisy.
Take voltage measurements at the transistor pins except the JFET gate pin. What numbers are on the transistors?
If the voltages are in the good range(search for Oktava 012 threads there should be good voltages listed in some)
Clean the PCB by the JFET.

High value resistors look good. Worst case would be changing a few parts. The JFET and PNP used are not that critical in that circuit.

The yellowish film sounds like a conformal coating that is peeling off.  The circuit does look similar to the 3 I have, although I have the old beige Russian boards with the traces that lift off if you are too aggressive with them.  They are great mics. The two I got from the now defunct Sound Room are outstanding, I bought a GC special on eBay as a test bed for modding. It’s on my list of things to do as this point. The capsule on that one isn’t of the same caliber and will be replaced.

If it were me and they fit the good Russian capsules (you could ask someone who works/worked on these a lot, like a Michael Joly (no longer modding, but a wealth of info) or a Bill Sitler,, who wants to sell mod kits), the first thing I would do is take the PCB and try to clean up the high Z portion with isopropanol, flux remover, etc to see if it makes any difference. If it is the same circuit, AND the legit capsules fit (the matched pair Russian ones I have are great), then you can consider replacing parts.

Is the mic preamp noisy without the capsule?  You may have to put a small cap (e.g., 50 pF) between the FET gate and ground to properly test that. I don’t know the capacitance of a real 102 capsule.

My only concern is that the mechanical quality of the Chinese hardware. Even if they fit, if there is not good electromechanical contact between the capsule and body, it will be a frustrating experience.  Just my opinion.

If you didn’t get what you paid for and are not in this for the long haul, you may just want to start over with the real thing

Gus said it all better than I did.

Gus said:

Have you tried the China built preamps in the housing without the capsules to check the noise?
Or better with a Oktava cap pad screwed on without the capsule?

If the preamps are noisy.
Take voltage measurements at the transistor pins except the JFET gate pin. What numbers are on the transistors?
If the voltages are in the good range(search for Oktava 012 threads there should be good voltages listed in some)
Clean the PCB by the JFET.

High value resistors look good. Worst case would be changing a few parts. The JFET and PNP used are not that critical in that circuit.

Click to expand...

I don't get much if any sound if I just test the preamp. I've tried it with both. The reason I figured it was the preamps was because all of the capsules have the same noise and output level, and I had heard that the Chinese capsules were decent. I haven't actually added any components to the PCBs though if that's important to test. I still can't get the one screw out. I ordered a 3/64 of an inch drill bit, I'm going to try slowly drilling into the screw and wearing it down enough that I can get the PCB of that body out.

Are you sure the screws come out? On some microphones you screw them in until the body slides off.

If the electronics with the capsules off are low noise it most likely is the capsules.

Do the China Oktava capsules screw on the MXL603 type bodies?
The inside picture of the China microphone in the recording hacks link looks like  China built SD internals in a Oktava casing.

Gus said:

Are you sure the screws come out? On some microphones you screw them in until the body slides off.

If the electronics with the capsules off are low noise it most likely is the capsules.

Do the China Oktava capsules screw on the MXL603 type bodies?
The inside picture of the China microphone in the recording hacks link looks like  China built SD internals in a Oktava casing.

Click to expand...

These bodies the screws are 1mm thick 3mm long phillips screws that come out. These bodies are very different than the Russian bodies. You actually push the entire PCB out by applying pressure from the xlr connectors.

According to this, the capsules are interchangeable

https://www.gearslutz.com/board/low-end-theory/33881-real-oktava-vs-fake-oktava.html

According to the recordinghacks link earlier, Oktava commissioned the Chinese ones!

Interestingly enough Bill Sitler says the Chinese capsules won't work on a Russian preamp. The guy on Gearslutz says they do and Russian ones work on the Chinese ones. I'm considering getting the Russian capsules if the preamps I have are fine, but if the capsules are good and the preamps are bad, I'd get the Russian preamps. The capsules all have the same output as well which is why I think it's the preamps (though the omni and hyper cardioid have really low output, and the cardioid has pretty normal output but still the same noise as the others).

Well, one could ask: what could be the cause of the noise in the amplifier?
The PNP transistor doesn't do any amplification, so it does not contribute much to the sound and/or noise.
The main suspect is the FET. Knowing the Chinese, they use anything that they have available...
What is the type number of the FET? I would first substitute the FET and also check the values of the polarisation and gate resistors. (Usually 680 M.ohm or 1 G.ohm.)

By the way: did you do the test with a (68 pF or so) capacitor instead of the capsule?
If the noise level is still high, it is clear that the amplifier body is the problem.

(I am almost tempted to buy a 'Chinese' MK-012 and see how we can improve things!  )

Question about the photos the first is blurry is there a input cap present?

When you say the microphone are noisy what are you comparing them to?

SD will often have more noise than a LD condenser

Do you have other SD microphones to compare the noise?

Do you know  that the audio interface or preamps has good P48 power?

How humid is it were you are testing the microphones?

You are not giving us the information we need to help. Voltages, do the capsules fit other microphones to test them, what part numbers on the transistors ?

Parts changes (mods) to the 012 are overrated on the web IMO. I have change parts in mine and compared them to others 012 and sometime the ones left stock are better for what is it used for.

I'm actually pretty bad at soldering, so I don't know how well me attempting to add or replace components will go. I'm actually trying to find someone to do repairs or mods on the Chinese versions, but none of the well known modders will touch it because it's a totally different microphone.

Gus said:

Question about the photos the first is blurry is there a input cap present?

When you say the microphone are noisy what are you comparing them to?

SD will often have more noise than a LD condenser

Do you have other SD microphones to compare the noise?

Do you know  that the audio interface or preamps has good P48 power?

How humid is it were you are testing the microphones?

You are not giving us the information we need to help. Voltages, do the capsules fit other microphones to test them, what part numbers on the transistors ?

Parts changes (mods) to the 012 are overrated on the web IMO. I have change parts in mine and compared them to others 012 and sometime the ones left stock are better for what is it used for.

Click to expand...

Comparing them to mics with similar noise levels. I have a SDC from 3U Audio with the same self noise and sensitivity and it is much quieter (self noise wise) and the capsules on it have much better output. Also compared the Oktavas to my iSK Pearls which were also much quieter (but they have a lower self noise @ 16 dBA)