On Mon, 14 Jun 2004 02:02:12 +0200, (Jazzman) wrote:

I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

I've been known to heckle at my bandmates when they do it, but I'd like
to know the real entity of the damage.

Most mics, especially vocal mics like the SM58, need much more than a
little tap to damage them. I've taken some big dents out of SM58
grills, and the mic's sound did not change before or after the dent
happened.
There COULD be some very fragile ribbon microphones, or condenser/tube
microphones. Anyone else have any experience of a microphone damaged
by tapping on it?
Mike T.

"Mike Tulley" wrote in message ...

Anyone else have any experience of a microphone damaged
by tapping on it?


Never, with a dynamic.... But I'd be very careful as to where and
how I might 'tap' a condenser or ribbon of any sort.

--
David Morgan (MAMS)
http://www.m-a-m-s DOT com
Morgan Audio Media Service
Dallas, Texas (214) 662-9901
_______________________________________
http://www.artisan-recordingstudio.com

"Jazzman"

I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

I've been known to heckle at my bandmates when they do it, but I'd like
to know the real entity of the damage.


** No damage can result from finger nail tapping - the diaphragm is way
inside and not touchable.

Now, blowing on a mic is another matter !




............ Phil

David Morgan (MAMS) wrote:

"Mike Tulley" wrote in message ...


Anyone else have any experience of a microphone damaged
by tapping on it?



Never, with a dynamic.... But I'd be very careful as to where and
how I might 'tap' a condenser or ribbon of any sort.


Yes for the ribbon because of its high compliance and
relatively large element mass but I've a hard time seeing
how tapping a condenser would hurt it. The mass of a
diaphram is so small that impact on the body would hardly
displace it unless accompanied by large displacement. Even
if it did move in and hit the the back plate, so what.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Jazzman" wrote in message
...
I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

I've been known to heckle at my bandmates when they do it, but I'd like
to know the real entity of the damage.

Out of habit from being in a studio and handling condensers, I always
lightly tap on the side of the barrel. It gets the point across.

"Bob Cain" wrote in message ...

David Morgan (MAMS) wrote:

Never, with a dynamic.... But I'd be very careful as to where and
how I might 'tap' a condenser or ribbon of any sort.

I've a hard time seeing
how tapping a condenser would hurt it. The mass of a
diaphram is so small that impact on the body would hardly
displace it unless accompanied by large displacement. Even
if it did move in and hit the the back plate, so what.

I suppose I'm more aware of my control room 'reaction'. Ever have
an acoustic guitar player cough or even exhale strongly toward, say
a KM-84 with no wind screen, and then reach down and touch it as
he apologizes? It's hard to imagine 'tapping' on the front of such a
mic.... body, no problem, front though? Scary.... I can't help but to
cringe as the TADs bottom out in the control room after 94dB of 10hz
rearranges the molecules in the walls and reminds you of the days
before 'sonic booms' were frowned upon. I should agree though,
there's no imminent danger to a condenser, either.

--
David Morgan (MAMS)
http://www.m-a-m-s DOT com
Morgan Audio Media Service
Dallas, Texas (214) 662-9901
_______________________________________
http://www.artisan-recordingstudio.com

In article writes:

I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

No harm if you don't use a very large hammer. It's much better to tap
on a mic than to blow into it, which is the usual stealth approach
when they don't want to say "Is this mic on?" or "Check one two".


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

"Mike Rivers" wrote in message
news:znr1087176307k@trad...

In article
writes:

I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

No harm if you don't use a very large hammer. It's much better to tap
on a mic than to blow into it, which is the usual stealth approach
when they don't want to say "Is this mic on?" or "Check one two".

Snapping your fingers an inch or two in front of the grille would
seem to be safe for any mic. Produces a nice sharp wavefront
that will attract attention, bounce a VU display or test the reverb,
etc.

In article writes:

Snapping your fingers an inch or two in front of the grille would
seem to be safe for any mic.

Well, yes, but that takes talent. And if you do it wrong, you could
produce a pretty good puff of air that might be harmful to the
diaphragm.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Ever have
an acoustic guitar player cough or even exhale strongly toward, say
a KM-84 with no wind screen, and then reach down and touch it as
he apologizes?

Or better yet, when they get up to come in & listen & hit the mic with the
guitar. Tiny little click out in the studio, big crash in the control room.

Scott Fraser

On Mon, 14 Jun 2004 02:02:12 +0200, (Jazzman) wrote:
I'm referring to the common gesture for trying if a mic is open: is it a
real bad thing to tap a dynamic mic's capsule? What about a condenser?

I've been known to heckle at my bandmates when they do it, but I'd like
to know the real entity of the damage.

TIA.

In drunken weddings/functions etc I've witnessed people picking up the
mic & holding it up to their ear like a telephone to hear if it's
on...

I've heard that if the diaphragm "bottoms out" for any reason on a phantom
powered condenser, there is the danger of minute spot welds forming.

I haven't attempted to verify this myself :-)

Ryan

Ryan Mitchley wrote:

I've heard that if the diaphragm "bottoms out" for any reason on a phantom
powered condenser, there is the danger of minute spot welds forming.

I haven't attempted to verify this myself :-)


Unlikely because of the huge resistance in series and the
small amount of charge that could be stored in that small a
capacitance.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Bob Cain wrote:
Ryan Mitchley wrote:

I've heard that if the diaphragm "bottoms out" for any reason on a phantom
powered condenser, there is the danger of minute spot welds forming.

I haven't attempted to verify this myself :-)

Unlikely because of the huge resistance in series and the
small amount of charge that could be stored in that small a
capacitance.

Yes, the polarization resistor is so high valued that it would not be much
to worry about. And it would have nothing to do with phantom power anyway.

It _is_ possible for big electrostatic loudspeakers to arc over if they
bottom out, but they have substantially larger area, greater distance between
the backplate and the diaphragm, and therefore enormously greater charge
involved. Even so, this can be prevented by careful engineering.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Fri, 18 Jun 2004 10:36:21 -0700, Bob Cain
wrote:



Ryan Mitchley wrote:

I've heard that if the diaphragm "bottoms out" for any reason on a phantom
powered condenser, there is the danger of minute spot welds forming.

I haven't attempted to verify this myself :-)


Unlikely because of the huge resistance in series and the
small amount of charge that could be stored in that small a
capacitance.


Bob

When the diaphragm bottoms out, there is no resistor at all in the
current path. The capacitor in a microphone is of a very high grade,
with virtually no losses, and there will indeed be a very high current
flow momentarily (English meaning of this word - ie for a moment, not
sometime soon) as the diaphragm hits the back plate. While I wouldn't
expect it to actually cause attachment, it would not surprise me if it
blew a tiny pinhole. Accumulate a few of those and you could well do
audible damage.

d
Pearce Consulting
http://www.pearce.uk.com

Ryan Mitchley wrote:

I've heard that if the diaphragm "bottoms out" for any reason on
a phantom powered condenser, there is the danger of minute spot
welds forming.

I haven't attempted to verify this myself :-)

You can't "verify" it with any modern microphone, since it isn't true.
Mylar film, which has been almost universally used as the diaphragm
material in most studio condenser microphones since the 1960s, is a
very effective insulator. Even if the diaphragm hits the backplate, no
current will flow--the gold layer is on the _other_ side of the Mylar.

With old-fashioned all-metal diaphragms this could be an issue according
to some folks; they say that little pinholes can be burnt. I've never
seen this myself, though. And it has nothing directly to do with phantom
powering. The issue is whether the capsule is externally polarized or an
electret.

--best regards

Don Pearce wrote:


When the diaphragm bottoms out, there is no resistor at all in the
current path.

I was discounting phantom as a source of current.

The capacitor in a microphone is of a very high grade,
with virtually no losses, and there will indeed be a very high current
flow momentarily (English meaning of this word - ie for a moment, not
sometime soon) as the diaphragm hits the back plate. While I wouldn't
expect it to actually cause attachment, it would not surprise me if it
blew a tiny pinhole. Accumulate a few of those and you could well do
audible damage.

Ok, then will you buy an energy argument? I'm too lazy to
plug in the numbers right now but I can't believe there's
enough energy on that little capacitor at 48 volts to
measurably raise the temperature of a mouse tear.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Bob Cain"


Ok, then will you buy an energy argument? I'm too lazy to
plug in the numbers right now but I can't believe there's
enough energy on that little capacitor at 48 volts to
measurably raise the temperature of a mouse tear.



** The formula is: V squared times C/2

If V = 48 volts ( often it is more) and C = 60 pF then the stored energy
is 69 nJ.



............... Phil

On Fri, 18 Jun 2004 22:17:31 -0700, Bob Cain
wrote:



Don Pearce wrote:


When the diaphragm bottoms out, there is no resistor at all in the
current path.

I was discounting phantom as a source of current.

When a microphone is in use the back plate is at a high DC voltage,
whatever the source of current.

The capacitor in a microphone is of a very high grade,
with virtually no losses, and there will indeed be a very high current
flow momentarily (English meaning of this word - ie for a moment, not
sometime soon) as the diaphragm hits the back plate. While I wouldn't
expect it to actually cause attachment, it would not surprise me if it
blew a tiny pinhole. Accumulate a few of those and you could well do
audible damage.

Ok, then will you buy an energy argument? I'm too lazy to
plug in the numbers right now but I can't believe there's
enough energy on that little capacitor at 48 volts to
measurably raise the temperature of a mouse tear.


Bob

No. The energy is 1/2 C V^2. I know it is not huge, but the incredibly
high quality of the capacitor means that when the diaphragm touches,
the power released is quite large. This is because the capacitor
discharges very quickly. The diaphragm is very thin, for obvious
reasons, and it is quite possible that there would be local ablation
of the metallisation where the touch occurred. You would probably need
a microscope to find it though.

d
Pearce Consulting
http://www.pearce.uk.com

Tapping the capsule does not cause the diaphragm to bottom out. That would
represent an SPL near or even past the mic's peak SPL-handling level. Which for
most mics is over 110dB. Unless you hit the mic with a sledgehammer, the thunk
isn't even remotely that loud.

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On 2004-06-14 (ScotFraser) said:
Ever have
an acoustic guitar player cough or even exhale strongly toward, say
a KM-84 with no wind screen, and then reach down and touch it as
he apologizes?
Or better yet, when they get up to come in & listen & hit the mic
with the guitar. Tiny little click out in the studio, big crash in
the control room.
Yah, had that happen with all sorts of instrumentalists, or the
drummer who uses the floor tom to hold his sticks and drops them on
the drum as he gets up to come in and have a listen.

Anybody who's recorded with me knows that I have a certain little
trip for the ring out of a last chord. I"ll hit the talkback and do
something like "shhhh, don't anybody move," and then when channels are
muted etc. and we're sure the last note has been allowed to ring out
and decay cleanly then I'll say something.


tHen there's the doofus who thinks the mic is a handy place to hang
his phones g.



Richard Webb, amateur radio callsign nf5b
active on the Maritime Mobile service network, 14.300 mhz
REplace anything before the @ symbol with elspider for real email

--



Amazing how much tape is on a 10" reel, when it's not, isn't it?