What OEM mic is this? (is it worth modding?)

I've got this JJlabs mic laying around and I want to know if it is worth modding. I know the mic is a rebranded chinese OEM mic, but which? Based on the images, do you think it is worth modding? The current sound is typical budget hyped mid-range, I would like something more flat (or close to the original U87 which I guess this mic is based on).

Check out:

http://www.groupdiy.com/index.php?topic=6582.0

telefunk said:

Check out:

http://www.groupdiy.com/index.php?topic=6582.0

Click to expand...

Thanks!
It looks rather similar to the ADK-51 mentioned in the thread (and thus also similar to the MXL 2001).
The ADK has two more resistors, thats about the difference it seams.

So if I want this thing to have a more neumann-esque sound (say U87 or U67), do I just change the capsule to k87 ( or k67) and the output transformer (and obviously change the terrible grille)?

No, the capsule is already "K67-esque"

The main problem is that it is an awfully over-bright mic.

Because U87 has a circuit that balances the freaquency response of the capsule, to make that mic anything even resembling the U87, you would have build the circuit completely from the scratch. It is much better to try to use some more linear capsule type, like the K47, together with some more transparent transformer, me thinks.

It is actually MXL 2003, for example. Ha det bra!

Keith "SSL-tech" once suggested to increase or even double the value of C3 in these mic's, to make them more agreeable..it works..
also, check what voltage you have on the drain. sometimes they are way off. ~10volt would be a good starting point, as that is the aimed for value in the circuit they copied. if it is way off, try adjusting the source resistor bypassed by that yellow tantalium cap.(R7)

without checking these things, you have a treble boost that might even be distorting due to miss-bias and it might be hard to tell that is what is happening, just thinking they suck on most courses ( ...what is the second harmonic on a 12kHz note when distorting?  )

all in all a 10 minute operation and pennies in parts...worth a try?

J

EDIT: schematic. http://www.xaudia.com/omnip/Mics/MicSchLib/mxl2001.gif

This mic look like the ADK mics. All of these mics share the same or similar circuit as the A51, V67g, 2001, Hamburg ETC. The front end of the mic circuit driving the Fet, has the same circuit as the U87 including the .47uf capacitor C5 that adds feedback into the circuit. There are several U87 schematics that I have seen that have a variety of capacitor values for C1 & C3. For C1 I have seen values of .01uf to .047uf. For C3 I have seen 100pf to 870pf. The capacitors C1 & C3 can be used to change the top end of the mic. You can use these values to tune these circuits to the capsules.

I saw one schematic from a vintage U87 (not on the web) that had C1 .015uf and C3 870pf Early 80,s build. (not U87ai)

Jim Jacobsen
JJ Audio

dumb question, would it be worth putting a variable capacitor in there to be able to "fine tune" the thing?

Yep it was a dumb question.... lol sorry.  The VC's look only to be in the PF range not the uf range.

Ok, so the short answer is: Mod it if you want to play with a low end mic.
I'll probably just invest in something better then...

How about a Black Knight? Heard great things about it.
My main use would be male vocals. For the moment I have a lightly modded Oktaka 319 (removed one layer of grille, added a thin copper mesh, and removed the discs on top of the capsule). I'm looking for something very flat and detailed.