Difference between LDC and SDC mics

[Grungegod67]

What is the difference between a LDC and a SDC mics? And what are the differences in sound....and which one would be better for mic'ing a kick drum?

 

[DJL]

What is the difference between a LDC and a SDC mics? And what are the differences in sound....and which one would be better for mic'ing a kick drum?

Hi Grungegod67, welcome to hr.com. When you get a chance, you should read the big sticky thread at the top of the mic forum http://www.homerecording.com/bbs/showthread.php?t=27030 it's a long read... but well worth it.

But in a nutshell... neither a LDC or SDC mic is better... dynamic mics are better for miking a kick drum IMO. Also most LDC mics or more colored than SDC mics... and SDC mics are normally more accurate than LDC mics. Anyway, I hope that helps you. Don

 

[PhilGood]

DJL really nailed it here, but I'd like to clarify a couple of things.

LDCs are mics with at least 1" condenser diaphram. "Pencil" mics are usually considered small diaphram, but that isn't always true. Any back electret mic is a true SDC. The diaphram can be anywhere from 6mm or smaller up to 14mm. The rest are actually medium condenser mics. Oktava MC012, MXL 603s, Neumann KM183, 184, 185 and the like are medium diaphrams. 14mm to about 25mm are medium.

I know that's splitting hairs but the reason is the smaller the diaphram, the quicker in responds to transient frequencies. The total scope of sound reacts more in unison on smaller diaphrams. The larger you go with the diaphram, the better the bass response. At least in theory. Then again, I just got home after a binge.

mshilarious, marik, Blue sound and DJL can probably give better technical explanations.

 

[Harvey Gerst]

LDCs are mics with at least 1" condenser diaphragm. "Pencil" mics are usually considered small diaphragm, but that isn't always true. Any back electret mic is a true SDC. The diaphragm can be anywhere from 6mm or smaller up to 14mm. The rest are actually medium condenser mics. Oktava MC012, MXL 603s, Neumann KM183, 184, 185 and the like are medium diaphrams. 14mm to about 25mm are medium.

I know that's splitting hairs but the reason is the smaller the diaphram, the quicker in responds to transient frequencies. The total scope of sound reacts more in unison on smaller diaphragms. The larger you go with the diaphram, the better the bass response.

AAAARRRGGGHHHHH !!!!!!!!

 

[chessrock]

Uh oh.

I think you made him angry.

 

[Harvey Gerst]

Uh oh.

I think you made him angry.

No, I just don't know where to begin as far as correcting him, so I just didn't bother. But I thought I should at least post a warning.

 

[punkin]

Give it to us Harvey...come on...rip into it!

 

[boingoman]

AAAARRRGGGHHHHH !!!!!!!!

Perhaps Phil should do a little reading as well.

 

[mshilarious]

mshilarious . . . can probably give better technical explanations.

Huh? I'm not a technical expert, more of an experienced hacker.

That bit about electret=SDC, that's wrong though.

 

[XLR]

If you get a chance to compare the fantastic low freq response of a DPA or similar quality small diaphragm omni with the low freq response of a comparable large diaphragm condenser, I think you'd agree that the size of the diaphragm isn't the issue. But it's something that you see frequently in retail catalog copy writing.

A big benefit of a small diaphragm is the potential for better off-axis response, a critical factor in stereo configurations. Many years ago large diaphragm condensers had lower self noise than small diaphragms, but not so today. But the retailers know that bigger means better in the consumer's mind, so they play that up, just like the "warmer" thing.

Tim

 

[PhilGood]

!~!!!!

AAAARRRGGGHHHHH !!!!!!!!

OK, Let me have it!! This is the way it was explained to me a long time ago. ALL of the pencil mics I have before getting the MXL style are electret mics.

Shure SM94: electret.
Carvin C90E: electret.
AKG C1000: Electret.
Realistic: Electret. (I was young!)
CAD ICM417: Electret.

Guess what?! ANY mic which can be operated on batteries IS AN ELECTRET!!!!!!!!!

If you've ever had a pencil mic that took a nine volt or AA. ELECTRET!!

Bottom line: Electrets ARE condenser mics. Electrets ARE small diaphram. Electrets HAVE to be small diaphram. Therefore: Electret = SDC!!

These are all smaller than 19mm, right? I understand that the Neumann KM184 style mics are called small diaphrams and I'm fine with that. In reality though, you don't go staight from small to large. do you? I was told by a rep. at NAMM that these were actually medium diaphrams. I repeat what I learn, same as you, and yes I have read this stuff about electrets. I've made electret mics!!


AAAAAAAARRRRRRRGGGGHHHHH!!!!!! is RIGHT!!!

 

[PhilGood]

Perhaps Phil should do a little reading as well.

from:

http://www.epanorama.net/circuits/microphone_powering.html#electretintro


Introduction to electret microphones

An electret MIC is the best value for money omnidirectional microphone you can buy. Electret microphone can be very sensitive, very durable, extremely compact in size and has low power requirements. Electret microhones are used in very many applications where small and inexpesive microphones with good performance characteristics are used. Electret microphone occupies (at a rough guess) the lower 90% of applications, quality wise. Most lavalier (tie-clip) microphones, consumer video camera microphones and microphones used with computer soundcards are electret microphones.

The electret is a modified version of the classic capacitor (or condensor) microphone, which exploits changes in capacitance due to mechanical vibrations to produce voltage variations proportional to sound waves. Whereas the condensor MIC needs an applied (phantom) voltage, the electret has a built in charge, and the few volts needed are to power the built-in FET buffer, not to create an electric field.

Typical electret condenser microphone capsule is a 2 terminal device (there are also 3 pin capsules) which approximates to a current source when biassed with around 1-9 volt and routinely consumes less than half a milliamp. This power is consumed by a very small preamplifier built into the microphone capsule which makes the conversion of very high impedance source of the electret element itself and the cable which needs to be driven. Be aware that this impedance is swamped at signal frequencies by cable capacitance so that at 1kHz the assembly will exhibit an impedance of a few 10's of K.

The electret is a modified version of the classic capacitor (or condensor) microphone

 

[PhilGood]

I even remember reading about the AKG C2000 when it first came out being listed as a "medium diaphram side adress microphone", since it was one of the first trying to compete with large diaphram mics.

 

[Harvey Gerst]

OK, Let me have it!! This is the way it was explained to me a long time ago. ALL of the pencil mics I have before getting the MXL style are back electret mics.

Shure SM94: electret.
Carvin C90E: electret.
AKG C1000: Electret.
Realstic: Electret.
CAD ICM417: Electret.

Guess what?! ANY mic which can be operated on batteries IS AN ELECTRET!!!!!!!

So, by your reasoning, the original Neumann U87 (which had batteries) was actually an electret mic? Because all of the particular "pencil" mics you have are electrets, you extend it to say that all "pencil" mics are electrets?

I have a pair of really obscure 1/2" Akai "pencil" cardioid mics that have a nice 12au7 inside them. I had a pair of nice 1/2" omni Capps pencil mics back in the 60's that used 12ax7's.

I also have a nice pair of Fairchild F-22's which runs off batteries - also a 1" diaphragm, and also not an electret.

If you've ever had a pencil mic that took a nine volt or AA. ELECTRET!!!!

These are all smaller than 19mm, right? I understand that the Neumann KM184 style mics are called small diaphrams and I'm fine with that. In reality though if you don't go staight from small to large. do you? I was told by a rep. at NAMM that these were actually medium diaphrams.

Sue me!

25mm is what most engineers would call a large diaphragm mic.

You also said:

Any back electret mic is a true SDC.

Explain my Sony ECM370 which is a 1" electret, an LDC.

And you also said:

The total scope of sound reacts more in unison on smaller diaphragms. The larger you go with the diaphram, the better the bass response.

Again, wrong on several counts. The "total scope of sound reacts more in unison on smaller diaphragms" statement is just bullshit. It's because there's a smaller area to prevent disturbing the sound field, and that gives SDC's the advantage in off axis response over LDC's.

As far as the "LD=more bass", the best low frequency extension you can get is with really good acoustical measurement mikes, like the B&K - all SDC's.

The problem is that you've taken a few isolated examples of "some things", and extended it to include "all things".

Your last post (showing a quote from some place), while interesting and quite factual, has nothing to do with your statement errors. Small omni electrets ARE a great value, and I've been hawking the use of the Behringer ECM8000's here for a long time, exactly for that reason.

You wanna keep this going? Fine with me. Your statements were wrong and that's all there is to it. There's nothing to debate here. You want some more proof, or shall we talk about credentials? Wanna take this over to Klause Heyne's forum, where a lot of the major mic designers hang out? The choice is yours; cling to what you believe, or actually learn something useful.

I'm not trying to dis you Phil, but I've been fighting misinformation for years.

 

[PhilGood]

Guess I'll post the answer here in case you missed the other post:

A more direct answer: (from previous post)

"Whereas the condensor MIC needs an applied (phantom) voltage, the electret has a built in charge, and the few volts needed are to power the built-in FET buffer, not to create an electric field."


In most cases of electrets the diaphram is small. I guess Sony figured out how to make a 1" that has a built in charge. It still has the FET if it's an electret.

 

[PhilGood]

The problem is that you've taken a few isolated examples of "some things", and extended it to include "all things".

OK, I see where we have the problem here. I thought by using the words "can" and "usually" in my original post I was making clear that this is not always the case and only applied to some instances, but I can see I was misunderstood.

 

[PhilGood]

Alright. Let's clean this up. I don't want a bad rep for being misunderstood and I don't want a fight with Harvey. I know your credentials and don't claim to come anywhere near them.

So, by your reasoning, the original Neumann U87 (which had batteries) was actually an electret mic? Because all of the particular "pencil" mics you have are electrets, you extend it to say that all "pencil" mics are electrets?

No, the U87 is a condenser. There's a difference. I don't understand how you think that was my reasoning. I meant that older pencil mics were "usually" electrets unless they were expensive esoteric mics.

I have a pair of really obscure 1/2" Akai "pencil" cardioid mics that have a nice 12au7 inside them. I had a pair of nice 1/2" omni Capps pencil mics back in the 60's that used 12ax7's.

I also have a nice pair of Fairchild F-22's which runs off batteries - also a 1" diaphragm, and also not an electret.

I didn't imply that all pencils were electret. If a mic can bias the diaphram and power the head amp off a battery, great!! "Usually" this would be an electret since it requires only 1-9v.

I should not have said if it runs off batteries - electret! This is not always true. In my defense, MOST of the time it is.

25mm is what most engineers would call a large diaphragm mic.

Here's where you should be getting on companies like Marshall. They say a 25mm is a 1". Some companies say a 32mm is 1".

Didn't I say 1" is LDC??

Explain my Sony ECM370 which is a 1" electret, an LDC.

If Sony can make a 1" capsule that can have it's own charge it's electret. Yes, this would negate my statement about electrets HAVING to be small, but in my defense again, this isn't usually the case.

Your last post (showing a quote from some place), while interesting and quite factual, has nothing to do with your statement errors. Small omni electrets ARE a great value, and I've been hawking the use of the Behringer ECM8000's here for a long time, exactly for that reason.

I agree! I've made some really nice sounding mics from cheap capsules. I bought the ECM8000s on your recommendation.

I'm not trying to dis yu Phil, but I've been fighting misinformation for years.

I understand that. I respect that. If I had phrased things a little better, it probably wouldn't have been interpreted that way.

I apologize.

 

[Harvey Gerst]

If you had said "usually" and "most of the time", or "some of the time", we wouldn't be having this discussion (except for the LD=more bass statement).

1" = 25.4mm. A 25mm diameter diaphragm would be considered a LD mic by engineers, not a "medium diameter" mic as you stated.

 

[PhilGood]

Thanks! Now I know!

 

[Marik]

Without getting deep into technical details, it is probably worthwhile to mention that their off-axis response different not only on HF, but also (due to the difference in their capsule construction) MOST OFTEN LD vs. SD mics exhibit different patterns vs. distance, on low end. Once again, here I have to stress "most often", as there are some exceptions.