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pressure buildup rings on Sennheiser mics



 
 
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  #1  
Old February 5th 09, 04:58 AM posted to rec.audio.pro
Ray Thomas[_2_]
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Posts: 106
Default pressure buildup rings on Sennheiser mics

I believe the 'pressure build-up' rubber rings that are supplied with the
Sennheiser MKH20 act as a sort of small-scale HF lift when the mic is used
in the diffuse field, and perhaps they also serve to increase directionality
(or modify the off axis response) slightly also ? Could the same principle
be applied usefully to any flat response omni mic used in the diffuse field,
or is it specifically applicable to the MKH RF mics....and how much lift
could one expect anyway, in real terms ?
Thanks for your advice,
Ray


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  #2  
Old February 5th 09, 09:06 AM posted to rec.audio.pro
Eberhard Sengpiel
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Posts: 5
Default pressure buildup rings on Sennheiser mics

Ray Thomas > wrote:
>I believe the 'pressure build-up' rubber rings that are supplied with the
>Sennheiser MKH20 act as a sort of small-scale HF lift when the mic is used
>in the diffuse field, and perhaps they also serve to increase
>directionality (or modify the off axis response) slightly also ? Could the
>same principle be applied usefully to any flat response omni mic used in
>the diffuse field, or is it specifically applicable to the MKH RF
>mics....and how much lift?



This pressure treble lift can also used in the direct field, when ever
you need more high frequencies. It's an acoustic equalizer.
You can use it without problems on "not flat" response omni mics,
(diffuse field equalized) if you need more treble.

Sennheiser MKH 20 omnidirectional condenser microphone:
A pressure build-up ring is included and is used to accentuate
high-frequency response.

A HF lift is used on other omni microphones in form of a sphere.
The pressure lift has nothing to do with the RF principle.

DPA sells for his 4006 omnidirectional condenser microphone
the "Acoustic Pressure Equaliser" APE L50B
http://www.dv247.com/invt/45557/

Schoeps sells for his MK2S omnidirectional condenser microphone
the "Slip-on sphere" KA 40 or KA 50.
http://www.musicians-gear.com/lin/da...oeps/ka_40.htm

Cheers Jens


  #3  
Old February 5th 09, 09:50 AM posted to rec.audio.pro
Ray Thomas[_2_]
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Posts: 106
Default pressure buildup rings on Sennheiser mics


"Eberhard Sengpiel" > wrote in message
...
> Ray Thomas > wrote:
>>I believe the 'pressure build-up' rubber rings that are supplied with the
>>Sennheiser MKH20 act as a sort of small-scale HF lift when the mic is used
>>in the diffuse field, and perhaps they also serve to increase
>>directionality (or modify the off axis response) slightly also ? Could
>>the same principle be applied usefully to any flat response omni mic used
>>in the diffuse field, or is it specifically applicable to the MKH RF
>>mics....and how much lift?

>
>
> This pressure treble lift can also used in the direct field, when ever
> you need more high frequencies. It's an acoustic equalizer.
> You can use it without problems on "not flat" response omni mics,
> (diffuse field equalized) if you need more treble.
>
> Sennheiser MKH 20 omnidirectional condenser microphone:
> A pressure build-up ring is included and is used to accentuate
> high-frequency response.
>
> A HF lift is used on other omni microphones in form of a sphere.
> The pressure lift has nothing to do with the RF principle.
>
> DPA sells for his 4006 omnidirectional condenser microphone
> the "Acoustic Pressure Equaliser" APE L50B
> http://www.dv247.com/invt/45557/
>
> Schoeps sells for his MK2S omnidirectional condenser microphone
> the "Slip-on sphere" KA 40 or KA 50.
> http://www.musicians-gear.com/lin/da...oeps/ka_40.htm
>
> Cheers Jens


Thanks Jens,

I'd seen pics of them before and wondered about their size and
construction....pretty hefty price on the DPA spheres of 57 UK pounds ! I
imagine the Schoeps items are similar in price. I was wondering if toy
balls (eg tennis balls or smoother items), or even rubber squash balls with
appropriate holes cut might function ok. I wonder if they'd need to be hard
.....like billiard/pool-table balls...or whether a softer foam or plastic or
rubber might work just fine, as I imagine it's the reflective surface
property which is decisive, rather than mass per se ? Certainly leaves a lot
of scope for experimentation.
Ray


  #4  
Old February 5th 09, 02:37 PM posted to rec.audio.pro
Jens Rodrigo
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Posts: 37
Default pressure buildup rings on Sennheiser mics

Ray Thomas > wrote:
> I'd seen pics of them before and wondered about their size and
> construction....pretty hefty price on the DPA spheres of 57 UK
> pounds ! I I imagine the Schoeps items are similar in price. I was
> wondering
> if toy balls (eg tennis balls or smoother items), or even rubber
> squash balls with appropriate holes cut might function ok. I
> wonder if they'd need to be hard ....like billiard/pool-table balls...
> or whether a softer foam or plastic or rubber might work just fine,
> as I imagine it's the reflective surface property which is decisive,
> rather than mass per se ? Certainly leaves a lot of scope for
> experimentation.



It's a good idea to build or find a small wooden ball.
The discussion about wood and its warm sound is interesting.
"Does wood really sound warm?" at rec.audio.pro
http://groups.google.com.au/group/re...24d9332d1370e5
The bigger the ball, the more the treble peak wanders to lower
frequencies.

Here is a Neumann pressure microphone with
spherical acoustic surface M50:
http://www.neumann.com/download.php?...d=lect0010.PDF
Look how the frequency response changes
with objects of different shapes.

Cheers Jens


  #5  
Old February 5th 09, 03:19 PM posted to rec.audio.pro
[email protected]
external usenet poster
 
Posts: 611
Default pressure buildup rings on Sennheiser mics

x-no-archive:

Jens Rodrigo wrote:
> Ray Thomas > wrote:
> > I'd seen pics of them before and wondered about their size and
> > construction....pretty hefty price on the DPA spheres of 57 UK
> > pounds ! I I imagine the Schoeps items are similar in price. I was
> > wondering
> > if toy balls (eg tennis balls or smoother items), or even rubber
> > squash balls with appropriate holes cut might function ok. I
> > wonder if they'd need to be hard ....like billiard/pool-table balls...
> > or whether a softer foam or plastic or rubber might work just fine,
> > as I imagine it's the reflective surface property which is decisive,
> > rather than mass per se ? Certainly leaves a lot of scope for
> > experimentation.

>
>
> It's a good idea to build or find a small wooden ball.
> The discussion about wood and its warm sound is interesting.
> "Does wood really sound warm?" at rec.audio.pro
> http://groups.google.com.au/group/re...24d9332d1370e5
> The bigger the ball, the more the treble peak wanders to lower
> frequencies.
>
> Here is a Neumann pressure microphone with
> spherical acoustic surface M50:
> http://www.neumann.com/download.php?...d=lect0010.PDF
> Look how the frequency response changes
> with objects of different shapes.
>
> Cheers Jens


> http://www.neumann.com/download.php?...d=lect0010.PDF


was interesting...

this mic, that many consider to be an excellent mic, has +6dB boost
at 10 kHz

Mark


  #6  
Old February 5th 09, 03:31 PM posted to rec.audio.pro
Don Pearce[_2_]
external usenet poster
 
Posts: 100
Default pressure buildup rings on Sennheiser mics

On Thu, 5 Feb 2009 06:19:57 -0800 (PST), wrote:

>x-no-archive:
>
>Jens Rodrigo wrote:
>> Ray Thomas > wrote:
>> > I'd seen pics of them before and wondered about their size and
>> > construction....pretty hefty price on the DPA spheres of 57 UK
>> > pounds ! I I imagine the Schoeps items are similar in price. I was
>> > wondering
>> > if toy balls (eg tennis balls or smoother items), or even rubber
>> > squash balls with appropriate holes cut might function ok. I
>> > wonder if they'd need to be hard ....like billiard/pool-table balls...
>> > or whether a softer foam or plastic or rubber might work just fine,
>> > as I imagine it's the reflective surface property which is decisive,
>> > rather than mass per se ? Certainly leaves a lot of scope for
>> > experimentation.

>>
>>
>> It's a good idea to build or find a small wooden ball.
>> The discussion about wood and its warm sound is interesting.
>> "Does wood really sound warm?" at rec.audio.pro
>>
http://groups.google.com.au/group/re...24d9332d1370e5
>> The bigger the ball, the more the treble peak wanders to lower
>> frequencies.
>>
>> Here is a Neumann pressure microphone with
>> spherical acoustic surface M50:
>> http://www.neumann.com/download.php?...d=lect0010.PDF
>> Look how the frequency response changes
>> with objects of different shapes.
>>
>> Cheers Jens

>
>> http://www.neumann.com/download.php?...d=lect0010.PDF

>
>was interesting...
>
>this mic, that many consider to be an excellent mic, has +6dB boost
>at 10 kHz
>
>Mark
>


As long as you know that, it is not a problem. If you need a flat mic
response, just use a parametric equalizer to remove the 10kHz peak.

d
  #7  
Old February 5th 09, 04:09 PM posted to rec.audio.pro
Scott Dorsey
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Posts: 16,688
Default pressure buildup rings on Sennheiser mics

Ray Thomas > wrote:
>I believe the 'pressure build-up' rubber rings that are supplied with the
>Sennheiser MKH20 act as a sort of small-scale HF lift when the mic is used
>in the diffuse field, and perhaps they also serve to increase directionality
>(or modify the off axis response) slightly also ?


Yes.

>Could the same principle
>be applied usefully to any flat response omni mic used in the diffuse field,
>or is it specifically applicable to the MKH RF mics....and how much lift
>could one expect anyway, in real terms ?


DPA sells ball-shaped "Acoustic Pressure Equalizers" that do similar things,
and you can make your own too. They come with frequency response plots
showing on-axis and 90' off-axis response changes. If you copy DPA's design
and make solid rubber 1" and 2" diameter balls, they should match the same
plots that DPA shows for their 1" and 2" balls. They should work with any
omni mike.
--scott



--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #8  
Old February 5th 09, 04:25 PM posted to rec.audio.pro
Scott Dorsey
external usenet poster
 
Posts: 16,688
Default pressure buildup rings on Sennheiser mics

> wrote:
>was interesting...
>
>this mic, that many consider to be an excellent mic, has +6dB boost
>at 10 kHz


If you're talking about the M-50.... that's +6dB on axis, but it falls
way off once you get off axis. Consequently when you pull it back into
the far field, the _overall_ far field response mixing up sounds from all
directions is about flat.

I'm no fan of the M-50, but it's a useful tool for some things. It's an
omni that's designed not to be omni at all at high frequencies. It gives
you the low frequency response of an omni capsule while still retaining
directionality to create stereo imaging.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 




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