Mic grill material -- perforated metal or mesh

[David Curtis]

Hi all,

I'm working on improvements to my Oktava ML52. I've read all of the
relevant past posts I could find. In particular, I found Michael
Joly's and Scott Dorsey's posts about their experiences helpful. The
consensus indicates replacement of the grill (among other things). I
can see/hear why -- it rings like a bell.

My plan (criticisms/suggestions welcome):

1) remove the hemispherical top and discard
2) cut away the narrow vertical fins in front and back of the shell
3) roll a grill from appropriate material and glue/fasten it in place
inside the modified shell
4) cut a disk of grill material and glue/fasten it in the top ring of
the shell
5) apply some dampening material (e.g., RTV) to the top ring (and
anything else that needs it)

My question is this: should I use wire mesh/cloth or perforated metal?
All of the DIY grills I've seen use wire mesh. On the other hand, I
note that many of the classic ribbon mics (RCA 44 and 77 among others)
use perforated metal plus silk. I haven't heard anyone suggest that
the grills on old RCAs should be replaced to improve the sound, and I
note that modern re-creations like AEAs stick with the perforated
metal. Perhaps this is because the perforated metal is important to
the authentic sound. Or, it could be because perforated metal is a
reasonable choice (assuming the right material, gauge, hole size and
spacing).

Does anyone have advice on this topic? Also, if perforated metal is a
good choice, does anyone have suggestions regarding material,
thickness, hole size and spacing? If I had a 77DX handy, I'd just
measure the hole pattern, but alas...

McMaster lists open area percentage for their perforated metals. I
assume that greater open area is better (more transparent). Is there a
minimum acceptable open area percentage?

Thanks,
Da5id

[Scott Dorsey]

David Curtis > wrote:
>
>My question is this: should I use wire mesh/cloth or perforated metal?
>All of the DIY grills I've seen use wire mesh. On the other hand, I
>note that many of the classic ribbon mics (RCA 44 and 77 among others)
>use perforated metal plus silk. I haven't heard anyone suggest that
>the grills on old RCAs should be replaced to improve the sound, and I
>note that modern re-creations like AEAs stick with the perforated
>metal. Perhaps this is because the perforated metal is important to
>the authentic sound. Or, it could be because perforated metal is a
>reasonable choice (assuming the right material, gauge, hole size and
>spacing).

You want it so that it doesn't ring. You should be able to tap it with
a pencil and hear a dull thunk. If you can do this effectively with
perfed metal, go for it. The problem with perfed metal is that it is
a custom job to get almost anything reasonable made. The old 77DX cover
is a great design and does not ring much at all, but if you go to Grainger
and pick up some perfed steel and roll it by hand, your chances are much
poorer. And your choices for perfed metal today are very limited; unless
you want a custom run you have only a limited number of patterns to choose
from.

>Does anyone have advice on this topic? Also, if perforated metal is a
>good choice, does anyone have suggestions regarding material,
>thickness, hole size and spacing? If I had a 77DX handy, I'd just
>measure the hole pattern, but alas...
>
>McMaster lists open area percentage for their perforated metals. I
>assume that greater open area is better (more transparent). Is there a
>minimum acceptable open area percentage?

Depends on what you can tolerate. You want the largest open area without
ringing.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

David Curtis > wrote:
>
>My question is this: should I use wire mesh/cloth or perforated metal?
>All of the DIY grills I've seen use wire mesh. On the other hand, I
>note that many of the classic ribbon mics (RCA 44 and 77 among others)
>use perforated metal plus silk. I haven't heard anyone suggest that
>the grills on old RCAs should be replaced to improve the sound, and I
>note that modern re-creations like AEAs stick with the perforated
>metal. Perhaps this is because the perforated metal is important to
>the authentic sound. Or, it could be because perforated metal is a
>reasonable choice (assuming the right material, gauge, hole size and
>spacing).

You want it so that it doesn't ring. You should be able to tap it with
a pencil and hear a dull thunk. If you can do this effectively with
perfed metal, go for it. The problem with perfed metal is that it is
a custom job to get almost anything reasonable made. The old 77DX cover
is a great design and does not ring much at all, but if you go to Grainger
and pick up some perfed steel and roll it by hand, your chances are much
poorer. And your choices for perfed metal today are very limited; unless
you want a custom run you have only a limited number of patterns to choose
from.

>Does anyone have advice on this topic? Also, if perforated metal is a
>good choice, does anyone have suggestions regarding material,
>thickness, hole size and spacing? If I had a 77DX handy, I'd just
>measure the hole pattern, but alas...
>
>McMaster lists open area percentage for their perforated metals. I
>assume that greater open area is better (more transparent). Is there a
>minimum acceptable open area percentage?

Depends on what you can tolerate. You want the largest open area without
ringing.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[David Curtis]

First: many thanks for the help, Scott.

(Scott Dorsey) wrote in message >...
> The old 77DX cover
> is a great design and does not ring much at all, but if you go to Grainger
> and pick up some perfed steel and roll it by hand, your chances are much
> poorer. And your choices for perfed metal today are very limited; unless
> you want a custom run you have only a limited number of patterns to choose
> from.

McMaster seems to have a pretty broad selection. I'm going to give it
a try. I'll let you know how it turns out, if you're interested.

--Da5id

[David Curtis]

First: many thanks for the help, Scott.

(Scott Dorsey) wrote in message >...
> The old 77DX cover
> is a great design and does not ring much at all, but if you go to Grainger
> and pick up some perfed steel and roll it by hand, your chances are much
> poorer. And your choices for perfed metal today are very limited; unless
> you want a custom run you have only a limited number of patterns to choose
> from.

McMaster seems to have a pretty broad selection. I'm going to give it
a try. I'll let you know how it turns out, if you're interested.

--Da5id

[Paul Stamler]

"David Curtis" > wrote in message
om...
> First: many thanks for the help, Scott.
>
> (Scott Dorsey) wrote in message
>...
> > The old 77DX cover
> > is a great design and does not ring much at all, but if you go to
Grainger
> > and pick up some perfed steel and roll it by hand, your chances are much
> > poorer. And your choices for perfed metal today are very limited;
unless
> > you want a custom run you have only a limited number of patterns to
choose
> > from.
>
> McMaster seems to have a pretty broad selection. I'm going to give it
> a try. I'll let you know how it turns out, if you're interested.

I've found that terminating the edges of a metal grille with something like
3M Strip-Calk helps cut down ringing, sometimes quite substantially.

Peace,
Paul

[Paul Stamler]

"David Curtis" > wrote in message
om...
> First: many thanks for the help, Scott.
>
> (Scott Dorsey) wrote in message
>...
> > The old 77DX cover
> > is a great design and does not ring much at all, but if you go to
Grainger
> > and pick up some perfed steel and roll it by hand, your chances are much
> > poorer. And your choices for perfed metal today are very limited;
unless
> > you want a custom run you have only a limited number of patterns to
choose
> > from.
>
> McMaster seems to have a pretty broad selection. I'm going to give it
> a try. I'll let you know how it turns out, if you're interested.

I've found that terminating the edges of a metal grille with something like
3M Strip-Calk helps cut down ringing, sometimes quite substantially.

Peace,
Paul

[Ben Bradley]

On 28 May 2004 20:23:35 -0700, (David Curtis)
wrote:

>Hi all,

>...

>My question is this: should I use wire mesh/cloth or perforated metal?
>All of the DIY grills I've seen use wire mesh.

Where have you seen these? I recall seeing pics of a homemade
grille on the Tech Talk forum of recording.org in the last year or
two, it looked pretty neat. ISTR it was wire mesh.

-----
http://mindspring.com/~benbradley

[Ben Bradley]

On 28 May 2004 20:23:35 -0700, (David Curtis)
wrote:

>Hi all,

>...

>My question is this: should I use wire mesh/cloth or perforated metal?
>All of the DIY grills I've seen use wire mesh.

Where have you seen these? I recall seeing pics of a homemade
grille on the Tech Talk forum of recording.org in the last year or
two, it looked pretty neat. ISTR it was wire mesh.

-----
http://mindspring.com/~benbradley

[David Curtis]

"Ben Bradley" > wrote in message
...
> >My question is this: should I use wire mesh/cloth or perforated metal?
> >All of the DIY grills I've seen use wire mesh.
>
> Where have you seen these? I recall seeing pics of a homemade
> grille on the Tech Talk forum of recording.org in the last year or
> two, it looked pretty neat. ISTR it was wire mesh.

Here are two of the best examples I've seen, where actual construction
techniques are discussed in detail:

http://www.omnipressor.com/Other/G7mics/Z-mesh.html
http://www.timcampbell.dk/micfab.htm

The second link wasn't up just now, but it was up earlier today. If it's
unavailable the first time you try, wait a day and try again. It's worth it.

--Da5id

[David Curtis]

"Ben Bradley" > wrote in message
...
> >My question is this: should I use wire mesh/cloth or perforated metal?
> >All of the DIY grills I've seen use wire mesh.
>
> Where have you seen these? I recall seeing pics of a homemade
> grille on the Tech Talk forum of recording.org in the last year or
> two, it looked pretty neat. ISTR it was wire mesh.

Here are two of the best examples I've seen, where actual construction
techniques are discussed in detail:

http://www.omnipressor.com/Other/G7mics/Z-mesh.html
http://www.timcampbell.dk/micfab.htm

The second link wasn't up just now, but it was up earlier today. If it's
unavailable the first time you try, wait a day and try again. It's worth it.

--Da5id