Ringing mics (housing, etc)

Archived from groups: rec.audio.pro (More info?)

I've been playing with a couple of MXL63M mics just for fun and
experimentation. Trying to find out more all the time.

I changed the .22uf ceramic and a .001uf ceramic to .47uf metal film and
the .001uf to a Styroflex ploystyrene cap. It's the Scheops similar
circuit and one that Scott has championed. Dan Kennedy suggested the
polystyrene for the gate of the FET. The change to metal film is
supposed to help clean up the top end. This particular mic already has
the two 1G resistors. I can't add another is series until Digi-key gets
some more in the middle of March.

The ringing is very pronounced and is not limited to the shell. In
fact, with the board suspended in the air, the board acts like a
microphonic tube when you thump it. The whole mic is now microphonic,
including the frame. I cleaned the board with Chemtronics Flux-off
2000, which is what I usually use.

There were a couple suggestions on Google for lining the shell with Gaf
tape, felt, silicon and velcro to eliminate the ringing.

My question has to do with the possibility of the ringing coming from
the board and the microphonics.

Any comments??

Wayne

Archived from groups: rec.audio.pro (More info?)

In article <37epqtF5cbtirU1@individual.net>, Wayne <ybstudios@aol.com> wrote:
>
>The ringing is very pronounced and is not limited to the shell. In
>fact, with the board suspended in the air, the board acts like a
>microphonic tube when you thump it. The whole mic is now microphonic,
>including the frame. I cleaned the board with Chemtronics Flux-off
>2000, which is what I usually use.
>
>There were a couple suggestions on Google for lining the shell with Gaf
>tape, felt, silicon and velcro to eliminate the ringing.
>
>My question has to do with the possibility of the ringing coming from
>the board and the microphonics.

Could be. Short the FET input to ground and see if it's still there.
Then lift the capsule from the FET input and see what happens.

Look for ceramic capacitors.

Apply power with the thing apart and start tapping on things with a
pencil and you will probably find some things that are more microphonic
than you'd like.

I'd worry more, though, about body resonances than any of that stuff.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

Well, I'd never figured a cold solder joint would cause ringing but it
did. Good news is - it wasn't one of my joints, bad news - it's was on
one of my mics.
The trace where the component pushes through had broken from the flat
trace. Looked ok, but no continuity.

Thanks, for the help,

Wayne



Scott Dorsey wrote:
> In article <37epqtF5cbtirU1@individual.net>, Wayne
<ybstudios@aol.com> wrote:
> >
> >The ringing is very pronounced and is not limited to the shell. In
> >fact, with the board suspended in the air, the board acts like a
> >microphonic tube when you thump it. The whole mic is now
microphonic,
> >including the frame. I cleaned the board with Chemtronics Flux-off
> >2000, which is what I usually use.
> >
> >There were a couple suggestions on Google for lining the shell with
Gaf
> >tape, felt, silicon and velcro to eliminate the ringing.
> >
> >My question has to do with the possibility of the ringing coming
from
> >the board and the microphonics.
>
> Could be. Short the FET input to ground and see if it's still there.
> Then lift the capsule from the FET input and see what happens.
>
> Look for ceramic capacitors.
>
> Apply power with the thing apart and start tapping on things with a
> pencil and you will probably find some things that are more
microphonic
> than you'd like.
>
> I'd worry more, though, about body resonances than any of that stuff.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."