Grid mod is bull-shit

I did Grid mod to one of my mics(remove inner metal mesh)
Guess what?

A lot of noise.

Why?

Because the mic pick up a lot of magnetic-electrical interference.

If there is no any other electrical equipment,even power cables,then the mod is ok(which is impossible,because there are power cables in the walls.),otherwise,Grid mod is bullshit.

Who invent this mod?

I noticed in my own designs that one layer of mesh most of the time is not enough. (Depending on the openings in the mesh of course.)
Sometimes the microphone was quiet, but when I came closer to the microphone, some hum was heard.
That is why I had to add a second layer of finer mesh to obtain a better screening. (Faraday shield.)
Impedances are extremely high, so you will pick up any electrical field that is 'in the air'.
Now try to put in the mesh again that you have removed. (If possible!...)

Many headbaskets -not just Neumanns- have three layers. This can (!) be overkill, especially in this day and age where just about everyone uses popfilters for close vocals. But like Ruud said, size of the mesh matters, too. As does size of the headbasket. Three layers on a small basket is not a good idea IMO (enclosed space, standing waves and such, as well as less transparency to the source). The C12 has a small head and only one layer. But yes, when there's only one layer, RFI can become a problem (depending on the studio, too).
Personally, I'm a fan of two layers; one coarse, one fine. Brauners are like that (very transparent and very quiet). The Behringer B-2 Pro and the DIY SYT-5 body (first generation) are like that, too.

maye4

This has been covered  in this forum before.  Some of us post about not taking out a grill mesh layer(s).

There are a few things going on with the mesh(s)
One it helps as a pop filter.  It also reduces split and other nasty things from being deposited on the capsule
Two it works like a Faraday cage
There are more things going on with the mesh

IMO Always question what you read on the web.

The microphone might work OK in someones house but what happens if you take it somewhere and there is more electromagnetic noise at different frequencies than in your house.

This may be obvious, but before you throw in the towel (it is hard to put that mesh back in).... depending upon how the remaining mesh is attached, it may not be solidly grounded to the case, or the case may not be solidly grounded, or you may have disturbed one of those grounds during the removal.  So verify that.  A mesh is a pretty substantial shield, even in one layer.

Verify BOTH sides of the mesh.

(And so as to avoid taking fire... I hear the other comments that have been made, and while I have not experienced the problem I want to be clear that I am not saying that one layer is enough, but simply that it is substantial, and a noticeable EMI difference when you are not recording in a room full of DC motors and Cell phones.. well it is sort of surprising.)

I'm doubling down with bruceO, please verify you have not disturbed the continuity between the various head-basket and body pieces. 

The obvious tell is for you to have the mic passing audio, now touch around the grille, head-basket and other body parts with your hands.  Does your interference increase with relation to touching the mic anywhere specifically?  If yes, you need to establish solid continuity throughout the entire case assembly, mesh etc.

Typing with a smile...

I'v re-installed my mesh.I took good care when I pulling it out.Now it's good as new.

And more:
It helped me located a magnetic-electrical radiation source-It's a old graphical eq...
This devil effected all my equipment in the rack.Now I turned it down.

I think this is diy and life:when you thought you messed it up,there is always hope and good things come unexpected.

After all:
Leave your mesh alone.

and:
use Iron sheets to isolate your transformers.

and:
Use Iron sheets as main material of your diy box.

I am glad I read this! I am not going to be removing the inner mesh anytime soon on any mic I own! I work in an area that has "dirty"(read:noisy) power. It is close to an idustrial section so recordings are usually done saturday night and sunday when the grid is the least "dirty". I do agree that the inner mesh can sometimes effect the tone but it can not be as bad as massive hum.

Sh*t! I removed one mesh one week before
Michael Joly will be bankrupt if this news will go outside the forum

I am glad you were able to fix the noise problem, and I am impressed with how you got the mesh out (and back in!) without damaging it (mine looked like chewing gum).  You have made me think twice about removing the mesh in my next mod, so I am listening.  But I think the EMI interference problem must be more than just the removal of a layer of mesh.

I have a "Royer Mod" circuit in an MXL body.  The 5840 mini-pentode is mounted with the capsule inside the head basket (lying on it's side) which makes the grid/capsule connection short, very short.

Now maybe it is because my grid connection is short, but I never have any electrical noise problems with this mic. I use it primarily on Cello, Double Bass and sometimes on vocals. The band always has cell phones (try as I might to find them) and I have never had a problem over many sessions and locations.

I have had wind noise problems with it (and it needs a pop filter for protection / plosives on vocals). But nothing electrical on that mic.

(And I think Michael has a lot of different mods and parts, I don't know if he removes mesh or replaces it with a different single layer mesh, but I have a pair of his modified Oktava SDC's which I like at lot).

ah sh****t, i did that to one of my mics and since i removed the inner mesh i started to get some interference problems, all of a sudden i heard a radio station pretty good.. I talk to one of my Clients shortly before a recording session and as soon as I pushed the phantom power button I was like "hold up..you hear that". I allready started to doubt my cables, my preamp, all kinds of stuff but now as you mentioned it, I never thought about the inner mesh.. DAMN, i ripped it apart and its allready gone. Any idea where we can get a new mesh??  I'm in Germany.. 

I find some of these claims...surprising.

Even a very large (like 2mm) mesh size is very effective at shielding, even up to almost 1GHz (which has a wavelength of almost 30cm).  Even at common FM radio frequencies (about 100MHz), 2mm shielding is like 70-90dB effective.  At electrostatic frequencies of 120Hz it might as well be a solid ground plane.  ;D

There's a reason the C12 microphone got away with a very large mesh size...

You would think Joly would be getting a lot more returns...

-James-

If you tear out the inner mesh and the outer mesh no longer makes a positive contact to ground, guess what? Hum! To do the mod oneself, one must take precautions againt building an antenna instead of a faraday cage. Some soldering could be neccesary to make a positive connection to ground. There is a reason Michael Joly's basket mod doesn't hum, he clearly knows what he is doing which is more than I can say for myself!

I completely agree. I had a 990 that I built a new headbasket grill for. I did it in perforated metal. I, at first, thought the hum was caused by the larger holes of the perforated metal, but upon inspection realized that the grill was not making proper contact to the mic body. I have had no problems with hum since I fixed it.

-James-

I pulled the inner mesh out of my old MXL 990 head basket. Never caused any problems for me, and I have a dirty humming bastard of a recording space.

I've pulled a few baskets, no hum problems here

Just because the inner mesh(s) have been pulled do not mean you will automatically have hum. In some mics when the inner mesh is pulled, the outer mesh no longer contacts the mic body for a positive ground connection. It is nothing a little soldering couldn't take care of though. Either way, it is best to try this on a mic you do not care as much about. That way if you do get hum, you can trouble shoot the mic without a major freak out as if it were an expensive one!

mabell313 said:

That way if you do get hum, you can trouble shoot the mic without a major freak out as if it were an expensive one!

Click to expand...

So I guess I shouldn't pull any mesh out of this C12?