[[email protected][_2_]]

I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

Is there an LDC shock mount that is actually designed by someone who
understands the mechanical circuit, and has optimized the relevant
parameters?

Sean Broderick

[Don Pearce[_3_]]

On Sat, 7 Jul 2012 22:13:01 -0700 (PDT),
" wrote:

I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

Is there an LDC shock mount that is actually designed by someone who
understands the mechanical circuit, and has optimized the relevant
parameters?

Sean Broderick

The parameters are easy enough to understand, and you can judge the
isolation efficiency for yourself with a quick calculation.

The system is actually a second order lowpass filter (12dB per
octave), and the turnover frequency is determined by the mass of the
microphone and the stiffness of the elastic.The -3dB frequency is

1 / (2 * pi) * sqrt (stiffness / mass)

A second figure also comes out of those - the preload. That is how far
the elastic stretches when you hang the microphone on it. Measure that
and you can use a simple rule of thumb.

To get a -3dB of 1Hz, you need a preload of 9.8 inches. The coupling
response is then -15 dB at 2Hz, -27dB at 4Hz etc.

So measure the preload you get hanging the mic on the band (with the
same number of strands as it will have when installed in the shock
mount) and measure how far the band stretches.

9.8 inches divided by the stretch gives the corner frequency. From
that frequency onwards, it is a simple -12dB per octave calculation.

In short, the floppier, the better.

Armed with that last calculation, you can evaluate shock mounts
accurately independent of manufacturers' claims.

d

[Scott Dorsey]

wrote:
I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

Is there an LDC shock mount that is actually designed by someone who
understands the mechanical circuit, and has optimized the relevant
parameters?

There are a bunch of them out there. Unfortunately they are designed
for specific microphones. Change the mass of the microphone, you need
to change the springs.

Your problems are made worse by the microphone itself having a whole
bunch of internal body resonances... excite one and it's a problem.

I'd suggest that you try replacing the bands with softer ones, say the
ones intended for hair barettes.... or you try adding mass to the
microphone body itself to try and bring the total system resonance point
down.

Those mikes look like an U87, but they weigh a whole lot less than a U87
and some of the internal resonance issues come from that as well.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Don Pearce[_3_]]

On Sun, 8 Jul 2012 10:42:46 -0400, "Soundhaspriority"
wrote:



wrote in message
...
I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

Is there an LDC shock mount that is actually designed by someone who
understands the mechanical circuit, and has optimized the relevant
parameters?

Sean Broderick

Sean,
I don't know a single shock mount design that can take it all out. A
mix of approaches can work very well. Combinations of different materials
and different geometries work better than a single approach.

Put something under the mike stand. If you're using a fold-up stand, go
to the market and buy a three-pack of plastic pot scrubbers, pads of
polypropylene plastic mesh. If you're using a stand with a cast base use a
slab of foam, or carpet fragment, or the pot scrubbers.

Bob Morein
(310) 237-6511

Actually I've been investigating rumble recently, and for a great deal
of it the stand and shock mount make no difference; it goes straight
along the cable. The cure for this, in a rumbly location, is to
terminate the main mic cable on the stand itself, then connect the
last few feet with some really thin, flexible cable - the stuff from
ear buds is good. Then for the mic suspension itself, put the boom
high and use a long, floppy rubber band that extends a good long way
under the weight. This will guarantee rumble-free recordings.

I don't know anything else that will, apart from moving far from roads
and railways, particularly the underground kind.

d

[Mike Rivers]

wrote:

I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

You should look at the one from Rycote (the blimp wind
screen folks)
http://www.rycote.com/products/invision_studio/

The good news is that it costs less than your V76T mic. At
about $120, it might not cost much less, though.



--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Scott Dorsey]

Don Pearce wrote:

Actually I've been investigating rumble recently, and for a great deal
of it the stand and shock mount make no difference; it goes straight
along the cable. The cure for this, in a rumbly location, is to
terminate the main mic cable on the stand itself, then connect the
last few feet with some really thin, flexible cable - the stuff from
ear buds is good. Then for the mic suspension itself, put the boom
high and use a long, floppy rubber band that extends a good long way
under the weight. This will guarantee rumble-free recordings.

It's normal practice to make a loop of cable and gaff the end down in order
to provide some isolation. Lighter and more flexible cable is needed if
you're doing something like booming, though, where isolation from cable
handling noise is really important.

The key to low rumble, though, is the internal design of the microphone.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[hank alrich]

Don Pearce wrote:

On Sat, 7 Jul 2012 22:13:01 -0700 (PDT),
" wrote:

I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

Is there an LDC shock mount that is actually designed by someone who
understands the mechanical circuit, and has optimized the relevant
parameters?

Sean Broderick

The parameters are easy enough to understand, and you can judge the
isolation efficiency for yourself with a quick calculation.

The system is actually a second order lowpass filter (12dB per
octave), and the turnover frequency is determined by the mass of the
microphone and the stiffness of the elastic.The -3dB frequency is

1 / (2 * pi) * sqrt (stiffness / mass)

A second figure also comes out of those - the preload. That is how far
the elastic stretches when you hang the microphone on it. Measure that
and you can use a simple rule of thumb.

To get a -3dB of 1Hz, you need a preload of 9.8 inches. The coupling
response is then -15 dB at 2Hz, -27dB at 4Hz etc.

So measure the preload you get hanging the mic on the band (with the
same number of strands as it will have when installed in the shock
mount) and measure how far the band stretches.

9.8 inches divided by the stretch gives the corner frequency. From
that frequency onwards, it is a simple -12dB per octave calculation.

In short, the floppier, the better.

Armed with that last calculation, you can evaluate shock mounts
accurately independent of manufacturers' claims.

d

A truly effective LDC shockmount probably costs as much or more than
that mic.

--
shut up and play your guitar * http://hankalrich.com/
http://www.youtube.com/walkinaymusic
http://www.sonicbids.com/HankandShaidri

[Don Pearce[_3_]]

On Mon, 9 Jul 2012 17:21:17 -0400, Ty Ford
wrote:

On Sun, 8 Jul 2012 11:00:28 -0400, Don Pearce wrote
(in article ):

Actually I've been investigating rumble recently, and for a great deal
of it the stand and shock mount make no difference; it goes straight
along the cable. The cure for this, in a rumbly location, is to
terminate the main mic cable on the stand itself, then connect the
last few feet with some really thin, flexible cable - the stuff from
ear buds is good. Then for the mic suspension itself, put the boom
high and use a long, floppy rubber band that extends a good long way
under the weight. This will guarantee rumble-free recordings.

I don't know anything else that will, apart from moving far from roads
and railways, particularly the underground kind.

d

Uh-oh, Don and I agree again! I was doing location audio in a car. I had the
mic rigged in the visor. As I situated myself in the rear of the car I
flopped the mic cable and heard it in the headphones.

I think some cables are more prone to it than others. I swapped out to a
length of Gotham GAC-3 and the vibration was greatly decreased.

Regards,

Ty Ford


Ty, we always agree when you are right. ;-)

d

[James Perrett]

On Sun, 08 Jul 2012 17:49:31 +0100, Mike Rivers
wrote:


wrote:

I'm looking for a real shock mount for an MXL V76t mic. All the shock
mounts I have seen don't actually decouple the mic from vibrations.
They all have elastic bands tensioned too high, and way too high a
mechanical resonant frequency. The rumble marches right on through.

You should look at the one from Rycote (the blimp wind screen folks)
http://www.rycote.com/products/invision_studio/

The good news is that it costs less than your V76T mic. At about $120,
it might not cost much less, though.



I'm surprised no-one else came up with that recommendation Mike - Rycote
have done quite a bit of R&D in order to get those shock mounts right and
they deserve some wider publicity.

James.

--
http://www.jrpmusic.net

[geoff]

Don Pearce wrote:

Actually I've been investigating rumble recently, and for a great deal
of it the stand and shock mount make no difference; it goes straight
along the cable. The cure for this, in a rumbly location, is to
terminate the main mic cable on the stand itself, then connect the
last few feet with some really thin, flexible cable - the stuff from
ear buds is good. Then for the mic suspension itself, put the boom
high and use a long, floppy rubber band that extends a good long way
under the weight. This will guarantee rumble-free recordings.

I don't know anything else that will, apart from moving far from roads
and railways, particularly the underground kind.

Hanging a loop of the (one) mic cable takes a lot of it out. Certainly a
rigid, or simply laid, cable connection to the mic or stand transmits the LF
stuff very well.

geoff

[geoff]

Soundhaspriority wrote:

1. The legs of the mike stand were suspended above the floor by
plastic pot scrubbers.


I also often pop blocks of simple foamed rubber (urethane ?) under mic-stand
feet.

geoff