Topic: Oktava MC-012 MODs

[Chuck]

I'm going to post them on another site. I'll have a link up as soon as  I can.

[Lee]

[Chuck]

I finally got my GC microphones completely modded. With much thanks and a garland of martian fire flowers to Todd for the 2SK170-BL 's. I plan to test them Sunday.

By the way, I figured out the specs on the set screws that hold the MC012's together. Look for M2.5mm x 5mm set screws if you need some to replace the stainless steel ones that break when you unscrew them. The stainless ones are more expensive, so I got the black ones with hex drive. The microphones seem a lot more "sturdy" with these. I feel confident that they won't come apart now when I pull the XLR's off of them.

I hope to have some WAV/SHN files soon that compare:
The GC un-modded MC012's using matched capsules and the
The "matched" un-modded MC012's using matched capsules
with the "modded" GC MC012's using matched capsules.

Well, I got the tests done. I just need somewhere to upload them. I've got SHN's and text files, 75 mb worth if someone would be willing to host them.

Unfortunately, the first set of tests with the GC microphones before I modded them are not included. Something in my set-up changed enough to make comparisons with those tests unreliable. This is what I did:

Oktava_MC012_PreMod
A pair of matched Oktava MC012 microphone bodies with matched cardioid capsules where used to make this recording as a reference.

Oktava_MC012_PostMod
A pair of unmatched Oktava MC012 microphone bodies with the same matched cardioid capsules as the PreMod recording were used for this recording. These microphone bodies were modified per the Scott Dorsey article, "Do It Yourself: Upgrade Your Oktava Microphone" article in Recording Magazine 09/2003.


These tests were performed in one morning using the exact same equipment set-up (except that just the microphone bodies were swapped). The microphones were oriented NOS (90 degrees - 11.7 inches apart).


Specifically, the PostMod microphone bodies were modified as follows using the parts mentioned in the article:
R1  (1) 680m resistor replaced with (2) 1000m .5 watt resistors in series
R2  (1) 680m resistor replaced with (2) 1000m .5 watt resistors in series
C1  680pf capacitor replaced with 820pf COG capacitor
C2  1uf capacitor replaced with 10uf tantalum capacitor
Q1  Transistor replaced with 2SK170-BL FET
The other up-graded components mentioned in the article were in place when the microphones were recieved. It seems the Oktava factory has been using better parts recently.

Thanks to Todd for his help in getting some of the parts needed to do this project.

calico (chuck@taperssection.com)
11-02-2003 CM

Well, I finally got the tests on a server Part 2!

This should do it. I still haven't had the time to do any critical listening yet. I did noticed a 1-2 db drop in gain after the mod. My first impression was that the microphones had a flatter sound. I'd really like to hear what everybody else thinks.

Here are the tests:

www.cs.fredonia.edu/~sisa1297/oktavamod

Many thanks to gsisak for the server space.

[Flarnet]

The difference is pretty subtle. The biggest difference is in the top end instead of (as I had read) in the low end.

I wonder what kind of noise and fidelity-improvements you could hear on tests where a real quiet source is recorded with lots of gain. I bet the freq. response-improvements are even more pronounced under such conditions.
Probably not worthwhile if 100% of the readers here are concert tapers though.

[Chuck]

So far, my impression is a subtle difference in the high end.
It seems more open. Another observation is they seem to have a 'flatter" response overall.

[Sterling]

Anyone have any of these comparisons anymore?

Sorry, found em'. Nice work Calico!

Anyone doing these mods anymore?

[Xpanding Man]

Is anybody still able to do these mods ? 

i'm totally game if someone can help, thanks

[dr.ph0b]

Is anybody still able to do these mods ? 

i'm totally game if someone can help, thanks

i could do it for you, but wont have time till Sept    ping me back then if you are still into it. or if you are handy with soldering/desoldering electronics, i can give you a how-to. but it can get tedious, and if you dont have much expirince with soldering/desoldering its easy to do some permanent damage