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Voxman · Posted: Sat Jan 28, 2012 5:38 pm Post subject: Single or Dual Diaphragm

The following is an excerpt from a 'Sound On Sound' article. I would be interested on your comments.

"It has long been known that single- and dual-diaphragm microphones 'sound' different to one another, and it has become almost traditional to employ dual-diaphragm capsules for vocal applications, where the inherent bass characteristics work well. Strangely, it seems that the reasons for the sonic differences were not fully understood until Guy Torio reported on the subject in a paper at the 109th AES convention in 2000.
It's quite easy to demonstrate that different diaphragm arrangements alter low-frequency polar response with proximity, as well as the amount of proximity effect, the combination of which has a knock-on effect on off-axis coloration. Put simply, for a given mic-to-source distance, a dual-diaphragm capsule tends to have a polar response that is less directional than its single-diaphragm equivalent. When used close to a sound source, a single-diaphragm cardioid has a polar pattern that tends to bulge towards omni around mid frequencies and more towards a loose figure-of-eight shape at low frequencies. Dual-diaphragm mics, when used close to a source, tend more towards a hypercardioid pattern at low frequencies, complete with the characteristic tail. At greater mic-to-source distances, a dual-diaphragm mic often has a noticeably slacker cardioid pattern, which widens even further towards omni at low frequencies. It's also worth noting that a dual-diaphragm capsule generally suffers less proximity effect and is less susceptible to plosive popping. These characteristics become important when selecting a mic for different applications.
For example, if you're miking in the far-field — a crossed pair in front of a choir or orchestra, say — a single-diaphragm capsule will provide a more accurate polar response, rejecting low-frequency sound from behind more effectively. It will also have a more accurate on-axis response, with less off-axis coloration. Conversely, if you're close miking, polar response at low frequencies is generally better with a dual-diaphragm capsule, particularly if the unwanted rearward sound sources are also in the near field".

My own mic is a Violet Amethyst Standard, and has a single diaphragm. I really have to wonder whether dual diaphragm mics are the way to go for voiceover? and whether dual ones could be slightly more forgiving with room acoustics. It's something which never seems to get raised.

Also, who out there with a single diaphragm mic gets great results, and with which mic???

Cheers
Peter

Frank F · Posted: Sat Jan 28, 2012 8:33 pm Post subject:

There are several "dual" diaphragm mic on the market, and some folks actaully use them for VO. One most notable microphone is the MKH 416, also known as a lo-bar pattern microphone.

Several manufacturers use a "dual" diaphragm in their mic as each side works together to form an omni patterned microphone (you might see this labeled as "multi-pattern" or some other marketing dribble); when only one side is active and the other is stabilized or inert, the pattern will become uni-directional or cardioid. Depending upon the bias of the capsule and FET in the circuit and the polarization - the lobes of the pattern will either enlarge or decrease in size in the near field

So without further dribble, a nice cardioid patterned mic. with a smooth single or dual diaphragm, proximity valid, low sibilance'd, warm lows, yet solid sounding microphone is good for VOists.

A ribbon microphone is a good example of a single "diaphragm", dual sided. omni patterned microphone.

Frank F
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Be thankful for the bad things in life. They opened your eyes to the good things you weren't paying attention to before. email: thevoice@usa.com

Voxman · Posted: Sat Jan 28, 2012 9:09 pm Post subject:

Thanks for that Frank

In saying 'dual diaphragm' I'm not referring to a multi pattern mic, rather a single pattern mic with a dual diaphragm like the Rode NTK or the Violet Amethyst Vintage.

Rob Ellis · M&M Joined: 01 Aug 2006 Posts: 2385 Location: Detroit

okay you guys are getting way too technical for me

Frank F · Posted: Sat Jan 28, 2012 11:29 pm Post subject:

Rob, I know, I know...

To keep it simple, a dual diaphragm capsule has both sides of the coin shape capsule (i.e.: front and back) as potentially active elements, although when used in the cardioid pattern only one side "works".

Many manufacturers buy a capsule with only one side of the capsule "active". the other side is simply a place holder - inert, non powered, dead. This concept design leaves a "hole" or "dead-space" behind the active side. There are pro's and con's of having an inert side or a non-polarized active element on the back of the capsule, the biggest pro for the manufacturer is cost - about $15.00 USD more for dual element capsules.

The Rode or Violet are good examples of dual active elements with only one side being used.

Frank F
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Be thankful for the bad things in life. They opened your eyes to the good things you weren't paying attention to before. email: thevoice@usa.com

georgethetech · Posted: Mon Jan 30, 2012 1:11 pm Post subject:

Peter, what are you missing in the sound you record with your current setup that you are trying to achieve, or are you just chasing the "perfect mic" legend?

There is rarely a reason for VO to consider a dual diaphragm mic, which usually has switchable patterns. Neumann TLM102 and TLM103, TLM67 are a single (to the best of my knowledge). So is the Mohave MA201FET, an awesome mic, and the CharterOak E700, another new one to the scene with amazing quality and extremely low noise.

Most ribbon microphones are actually a "figure 8" pattern, with a very high amount of side rejection and equal but out of phase pickup on either the front or back.
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If it sounds good, it is good.
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GeorgeThe.Tech
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Voxman · Posted: Mon Jan 30, 2012 2:31 pm Post subject:

Actually George, probably all of the above. The Sound On Sound article I was quoting from, appeared in with the review of the Violet Amethyst Standard and Vintage mics. I found it interesting and really wondered whether I would have been better to have gotten the Vintage model which has a dual diaphragm fixed cardioid instead of the Standard model which has the single diaphragm. I drew from the article that maybe a dual diaphragm fixed carioid might produce a cleaner more focused low end on my sometimes boomy voice and just be maybe more forgiving in this region. My recording space is a fairly well treated booth with bass traps and a slat resonator, I would rather have a larger recording space. I go through a GAP73 into a Duet1. I do wonder whether the Amethyst Standard mic is the best mic for me. The only other mic I've had was a Rode NTK but then my space then wasn't as well treated. How great it would be, to be able to bring home say 20 mics and try them all out........ microphone heaven.

georgethetech · Posted: Tue Jan 31, 2012 2:54 pm Post subject:

Wondering how others with good ears think you sound? Post a clip!
I have a Dropbox just for this sort of thing, if you'd like my opinion.
_________________
If it sounds good, it is good.
George Whittam
GeorgeThe.Tech
424-226-8528
VOBS.TV Co-host
TheProAudioSuite.com Co-host
TriBooth.com Co-founder

Marik · Joined: 31 Jan 2012 Posts: 9 Location: SLC

The description in S on S article is quite generalized, but here is the original article from Guy Torio buried on Shure website. Since Shure changed their site layout it is impossible to find it there, so here is the link:

http://www.shure.com/idc/groups/public/documents/webcontent/pdf_ea_dual_diaphragm_mics.pdf

It is a must reading for anybody interested in microphones and their operation.

Best regards, M
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Mark Fouxman
Samar Audio & Microphone Design

www.samaraudiodesign.com

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