Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #20 on: August 05, 2019, 10:07:13 AM »
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!  :P )
The FETs don't have any visible writing I can see, so I'm guessing they're pretty cheap. I haven't tested with a capacitor because I'm pretty bad at soldering. I don't have the steadiest hands.


Khron

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #21 on: August 05, 2019, 10:17:02 AM »
Rest your wrist(s) on the edge of the table / desk? Maybe aid positioning with your pinky? That's what i usually do.

I don't have one of those alligator-clip-equipped "helping hands" thing, but i have a small "machinist vise" that came with the press-stand for my "dremel" that i use for holding small PCBs in one place.

https://images.homedepot-static.com/productImages/10329769-30b7-42e0-8a6c-4a6f0748430b/svn/proxxon-vises-28132-64_1000.jpg

The FETs don't have any visible writing I can see, so I'm guessing they're pretty cheap. I haven't tested with a capacitor because I'm pretty bad at soldering. I don't have the steadiest hands.
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #22 on: August 05, 2019, 04:46:51 PM »
Dont mean to be a partybreaker, and start raving about capsules again, but chinese and russian capsules are nothing alike.

The chinese one has the same exact construction as MXL601, and bunch of others. The only difference might be the front grille. All of that = sharp spike, or 10db dip at about 8K.

You might just buy Takstar CM60 for about 25$ which has the same capsule, and is rather quiet.

Russian capsules have way more bottom end, and are less bright. Bad QC of russian capsules is usual BS, and a rumor that comes from usual sources.

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #23 on: August 06, 2019, 11:56:03 PM »
Finally got that stripped screw out. Took quite a bit of drilling but it's finally out. The transistors on this one actually do have writing on them. I'll see if I can make it out.

The first one close to the capsule connector says "2N 5457 414" and the second one says "2N 5401 Y-309"
« Last Edit: August 07, 2019, 12:02:20 AM by Icantthinkofaname »

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #24 on: August 07, 2019, 01:45:46 AM »
Cleaning the PCB didn't do anything. Interestingly enough I actually do get sound without the capsules connected. It's a hiss like you'd normally expect from preamp and mic noise, and it's still quite loud, but it's seperate from that wind sound I'm getting, so maybe the capsules are the issue. I didn't solder a capacitor to test though, I just listened to the white noise the preamp had, which was seperate from my interface preamp's white noise.

I actually came up with an interesting test. I don't know if this proves anything but I touched the pin of one of my 3U Audio capsules to the connector of the MK-012 and while it didn't work too well (because it wasn't a tight/proper connection) there was a lot of buzz, but it got some signal. Very little, I actually had to turn my preamp all the way up ti get it to clip, but there was nowhere near as much noise as the Chinese made MK-012 capsules. I don't know if this actually proves the Chinese capsules are faulty, but I'm a lot more confident in the preamps now. I'm actually gonna order the hyper cardioid Russian capsules from Thomann. I'm actually only interested in the hyper cardioid capsules anyway (I already have a pretty decent pair of cardioid SDCs in the iSK Pearls, and when my iSK Little Gems come those should be decent with the omni capsules), I just bought the set because it was only $300 USD. Ironically the only capsules that have decent output but still noise that came with the MK-012s is the cardioid set of capsules.
« Last Edit: August 07, 2019, 05:45:28 AM by Icantthinkofaname »

Gus

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #25 on: August 07, 2019, 05:58:05 AM »
Question about the photos the first is blurry is there a input cap present?

Can you take a better photo?

transistor numbers look good

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #26 on: August 07, 2019, 06:47:39 AM »
Question about the photos the first is blurry is there a input cap present?

Can you take a better photo?

transistor numbers look good
I  can try to. I really just have my phone's camera. I'll try manually adjusting some settings.

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #27 on: August 07, 2019, 06:53:30 AM »
Here's the front, hopefully this is a better picture.
« Last Edit: August 07, 2019, 06:59:37 AM by Icantthinkofaname »

Gus

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #28 on: August 07, 2019, 07:11:41 AM »
Looks like a SMD ceramic input cap hopefully a C0G.

Is there any flux on the caps?

Re: Will Chinese MK-012 capsules work on the Russian preamps?
« Reply #29 on: August 07, 2019, 07:25:14 AM »
Looks like a SMD ceramic input cap hopefully a C0G.

Is there any flux on the caps?
I don't see any flux, but I did clean the PCBs. There was something on the one, but even after cleaning it the noise levels remained the same.

The transistors in both mics are identical. I opened up the first one and used a flashlight, the writing is the same.

I'm thinking I'm gonna order some of the newer Russian hyper cardioid caps from Thomann and see if the noise is there with those capsules. If not I know there's something wrong with the Chinese ones I have. I'm just surprised that they all have the same issues and output level if some of them are defective.


 

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