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Cardioid dynamic microphone construction Modular Synthesizers
Old 1st September 2011
  #1
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb Cardioid dynamic microphone construction

Folks,

I'm interested in learning about the internal construction of directional dynamic microphones. Most of the info I've seen shows slots along the body, and mentions an "acoustic phase shift" network that delays sound arriving from the rear. I don't have such a mic to take apart, so I'm hoping one of the technical experts here can tell me specifically how this is done. An article at the Sound on Sound magazine web site shows a series of baffles, like a labyrinth, and maybe that's correct. But I'm hoping for positive confirmation.

Thanks.

--Ethan
Old 1st September 2011
  #2
Lives for gear
 
MicDaddy's Avatar
 

Dig through the older patents, there's a ton of info
Old 1st September 2011
  #3
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

^^^ Thanks. I've done that, but I wasn't able to find exactly what I'm looking for in the form of a clear drawing or photo of a directional microphone disassembled. If you have a direct link, I'd sure be grateful.

--Ethan
Old 1st September 2011
  #4
Lives for gear
 

When I read about this stuff close to 45 years ago, I'm thinking that it was a paper from EV. Not sure, and not sure if it is still available, but 'venting' was a big part of the performance of the whole "RE" line of microphones... notably the 11, 15, 18, and of course, the RE20.
Old 1st September 2011
  #5
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

^^^ Right Bill, but trying to find photos of the innards, to see how they actually do it, has proven very difficult!

--Ethan
Old 1st September 2011
  #6
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JohnRoberts's Avatar
 

If just trying to figure out how it works maybe search for old original patents on the technology when it was new.

No pictures but drawings and a description of what it is doing.

JR
Old 2nd September 2011
  #7
Lives for gear
 

i recall having seen two methods
sound goes past the mike
and enters via slots
which delays each signal path

another has various circuits inside
doing similar things
can be mechanical
but i vaguely recall seeing one that was electrical

shoot an email to bruce bartlett
i bet he can tell you for sure

try asking on the shure site
they may have some papers that explain it
Old 2nd September 2011
  #8
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

Quote:
Originally Posted by oldeanalogueguy View Post
shoot an email to bruce bartlett
i bet he can tell you for sure
I emailed Bruce yesterday (before seeing this post), and he replied with some helpful advice. MicDaddy also PM'd me, and maybe he can add more.

Thanks to all.

--Ethan
Old 3rd September 2011
  #9
Lives for gear
 

Besides the fixed venting found on most dynamics, I thought that I would mention an interesting feature on one of my old Telefunken condensers, probably made by Schoeps. It has little louvers in the back hidden inside the grille, moving the pattern control switch is like opening and closing Venetian blinds.

What about David S.?
Old 3rd September 2011
  #10
Gear Guru
 
Ethan Winer's Avatar
 

Lightbulb

^^^ Interesting Bill. I like mechanical filters and louvers!

I've been back and forth a few times now with Bruce Bartlett, and he's been very helpful and accommodating. So I'm pretty much done now with my mics chapter. I even learned some good stuff! heh

--Ethan
Old 4th September 2011
  #11
Gear Maniac
 
fredv's Avatar
 

Learning is good. I've been work on ribbon motors and preamps. The thing that is kicking my butt is trying to find fab shops that can make the parts for the design I want.
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