The "why not LDCs on stage for vocals" thread

[Immanuel]

(edit: I guess this thread should have been placed in "The Live Music Experience"? I will go ask the mods to move it)

I've not tried using an LDC mic for vocals on stage, but I have often heard and read that it is a no-go. The reasons I hear are:
1) They are too sensitive and will feed.
2) They are better at picking up stuff from far away and therefor gets more bleed.

I would like to challenge these points from a purely rationalistic viewpoint. The main reason behind this thread, however, is that I would like to really understand this on a deeper level, so if I am proven wrong, then that is good too. I might go shopping for an LDC, but I don't want to spend the cash, if I can not bring it on stage.

re 1) If a mic is too sensitive, then just turn it down. When you turn it down, you also turn down the "ambience" (in lack of better word for signal from on stage monitors etc.) . A mic's sensitivity does not alter the "direct signal" (here the singer) to ambience ration.

re 2) It doesn't matter, how far away a sound is. A microphone "measures and reports" air pressure at the location of the itself. The design of the mic can not change how much air sound sources can move from different locations.


So what are the actual reasons why we don't hear those nice big LDCs on stage? Is it because:
a) Due to proximity effect, you'd need to be farther away and thus you mess with the "direct signal" to "ambience" ration?
b) LDCs often have a more messy off axis response that gets you into trouble with feed back?

If these are the reasons, could they be remedied by using omni pattern (or maybe figure 8 for case b)?
Omni will get you more bleed, but it will take away the proximity effect. Could it actually be used in a "less loud on-stage SPL" scenario?
And how about figure 8? You will get the proximity effect, but it should often be possible to get the mic and monitors placed, so that the monitors are close to the 90¤ null.

[pounce]

very few folks could use them and get away with it.

many folks have too much volume onstage for it to work with respect to feedback and bleed.

also, it does cover your face up more, and you can't hold it and move around the stage. so that is a big negative for most acts. and you might not want to see an act where everyone just stands still.

some acts can get away with it, or at least get away with more condensers than normal if they are very naturalistic sounding, have low stage volume, and don't move too much. i thought allison krause and union station had quite a few nice ldc's in the mix live. they are an exception.

even i've been able to use things like a aea r84 ribbon mic onstage for a barbershop quartet show i work once a year. they love it, and it's a good match for them. but it's a real specific application. it would not work for a rock show.

[meLoCo_go]

Aren't it because they are too expensive and fragile to give to a crazy stoned dumbfuck every night?

[pounce]

no doubt

i wouldn't just use them with any rock band. i DO use them in orchestra pits extensively, but i don't think that's what the original post is about.

if you were the band and it fit your style you could make it work. but i wouldn't just throw em up there for any band to use.

[clicktrack]

I wouldn't say "Never" use...

Just rarely.

Very rarely.

A Piano-bass-drum-vox jazz band? Maybe. Especially if the mic fits the singer well.

In that case, positioning of the instruments can be optimized to avoid significant bleed between players and you have space to move the monitors etc.

As well, some may like the esthetic it allows for the "look" of the show.

But, as pounce says, thats a very specific circumstance.

Other than those specific circumstances, I'd choose something else than an LDC.

[Tim Armstrong]

re 1) If a mic is too sensitive, then just turn it down. When you turn it down, you also turn down the "ambience" (in lack of better word for signal from on stage monitors etc.) . A mic's sensitivity does not alter the "direct signal" (here the singer) to ambience ration.

If you turn down a mic, you reduce the volume of everything including the vocalist. But you seem to be saying that, right?

re 2) It doesn't matter, how far away a sound is. A microphone "measures and reports" air pressure at the location of the itself. The design of the mic can not change how much air sound sources can move from different locations.

Here's what I know, when I record a vocal with a dynamic mic like an SM58, I don't generally hear the dog barking down the street or the airplane flying overhead. When I record a vocal with a condenser like a KSM27, I DO also capture those sounds. The LDC mics I've used are a whole lot more sensitive and capture much more of what's going on in a larger area.

I've gotten good results using an LDC on a bluegrass band who wanted to do the old-time "one mic" thing, and I could see it working just fine for a solo or duo acoustic act. But forget about monitors!

Cheers, Tim

[Jasco]

Aren't it because they are too expensive and fragile to give to a crazy stoned dumbfuck every night?

My thoughts exactly.

[Bob Olhsson]

Bluegrass musicians gather around a LDC or two a lot!

It means low level, in-ear or NO stage monitors and the house can't be set on "stun." It can still be lots louder than most people seem to assume. It also requires minimal mixing and can easily be split off for a live netcast.

I happen to think this approach serves music way better than 90% of what I run into in most venues today. When is the last time you heard a member of the audience complain about the music not being loud enough as opposed to just the vocals?

[pounce]

no doubt

the ribbon mic i use on the barbershoppers sounds fantastic! you just can't do that very often.

[ggunn]

Here's how I understand it, and if I'm not technically correct, I'm sure someone will tell us.

Every mic has a linear range where the voltage output is directly proportional (or logarathmically proportional, whatever) to the SPL at the diaphragm. Above the linear range (in SPL) the mic is in saturation and no matter how loud things get, the mic can't push any more voltage. Below the mic's threshold (the low end of the linear range), the signal produced by the mic falls away much faster than does the SPL. The thing about LDC mics is that they have a very low threshold, so they pick up and generate signal for stuff that a dynamic mic won't hear very well, including the sound from a monitor speaker. Hence, they have a great propensity to generate feedback.

When they say a mic will pick up sound from farther away, of course that's rubbish; a mic doesn't know or care how far away a sound wave was generated (excluding proximity effect). What they really mean is that the mic has a low threshold, i.e., more sensitivity at low SPL.

[Tim Armstrong]

When they say a mic will pick up sound from farther away, of course that's rubbish; a mic doesn't know or care how far away a sound wave was generated (excluding proximity effect). What they really mean is that the mic has a low threshold, i.e., more sensitivity at low SPL.

Gordon, thanks for that explanation! Now I can more accurately describe what's happening. :D

:Thumbsup:

Cheers, Tim

[Immanuel]

If you turn down a mic, you reduce the volume of everything including the vocalist. But you seem to be saying that, right?

Yes, but then that is because I get more vocal signal in the first place anyway because the mic is more sensitive.

[Immanuel]

Here's what I know, when I record a vocal with a dynamic mic like an SM58, I don't generally hear the dog barking down the street or the airplane flying overhead. When I record a vocal with a condenser like a KSM27, I DO also capture those sounds. The LDC mics I've used are a whole lot more sensitive and capture much more of what's going on in a larger area.

Here's how I understand it, and if I'm not technically correct, I'm sure someone will tell us.

Every mic has a linear range where the voltage output is directly proportional (or logarathmically proportional, whatever) to the SPL at the diaphragm. Above the linear range (in SPL) the mic is in saturation and no matter how loud things get, the mic can't push any more voltage. Below the mic's threshold (the low end of the linear range), the signal produced by the mic falls away much faster than does the SPL. The thing about LDC mics is that they have a very low threshold, so they pick up and generate signal for stuff that a dynamic mic won't hear very well, including the sound from a monitor speaker. Hence, they have a great propensity to generate feedback.

When they say a mic will pick up sound from farther away, of course that's rubbish; a mic doesn't know or care how far away a sound wave was generated (excluding proximity effect). What they really mean is that the mic has a low threshold, i.e., more sensitivity at low SPL.

Thanks for the explanation. As it is hard to argue against people's practical experience (here the one of Tim), it just never made sense to me. :Thumbsup:

[pounce]

with something like an ldc, if you had any sort of "rock band" then certainly everytime you wanted to turn up the vocals you'd also be turning up the guitars and drums and such as an ldc would pick it all up. so you'd never have as much control as you'd like in that respect. the band would have to be pretty balanced on their own for this to make sense. i'm not against the idea, but it's for specific situations.

[Bob Olhsson]

Proximity effect actually goes on forever!!

The LF response of the velocity (aka figure-8) component below the diaphragm resonance always declines with distance. A cardioid is 50/50 velocity vs. pressure. A figure-8 is 100% velocity and an omni ia all pressure and has no proximity effect.

Another factor seems to be the mass and rigidity of the moving system. It's amazing how much less traffic noise a 57 picks up compared to other cardioid mikes.

[Halsu]

Thanks for the explanation. As it is hard to argue against people's practical experience (here the one of Tim), it just never made sense to me. :Thumbsup:

It's never made any sense to me either. I think the main issue here is distance from the source to the mic. People practically eat the dynamic mics, and LDC:s are often used from a bit further away.

If you sing 4 inches away from the SM58, you'll get the same leakage and feedback problems people associate with LDC:s.

BTW, it's nowdays quite common to see cheap chinese LDC:s in front of guitar cabinets at live gigs here in Finland, instead of the traditional SM57 or similar. I suppose they work well, otherwise they wouldn't be used, right? Have you seen this happen on your side of the pond?

[Immanuel]

Proximity effect actually goes on forever!!

The LF response of the velocity (aka figure-8) component below the diaphragm resonance always declines with distance. A cardioid is 50/50 velocity vs. pressure. A figure-8 is 100% velocity and an omni ia all pressure and has no proximity effect.

Another factor seems to be the mass and rigidity of the moving system. It's amazing how much less traffic noise a 57 picks up compared to other cardioid mikes.

Thanks, I guess I should go read some basic information on microphone design. Any experience with using those LDCs in omni and stepping up close then?



Have you seen this happen on your side of the pond?

If you are talking to me, that'll be the little pond, as I am from Denmark (was in Finland 5 or 6 times). To be honest, most often I do not pay attention to the gear, when I go to hear a live concert.

[nobby]

I'm certainly no FOH, BUT...


I did stay at a holiday inn express last night :grin:


Notice what, and how people are using, and ignore my tortured syntax :grin:

On stage, that's usually dynamic mics. Dependable, rugged, dynamic mics, and usually nothing more expensive than an AKG421.

W.C. Fletcher says you can do an entire studio recording with nothing but SM57s, in fact.

There are a few condenser mics - Shure SM87, AKG C535 come to mind - that are designed for stage work, but you wouldn't want to prance around a stage at a death metal (or even chronic illness metal) gig with them.

[Tim Halligan]

LDC mics for vocals?

In rock music?

Sure...why not?


Especially when the singer uses the Proximity effect of the microphone...

Purely Pleasant plosives will surely pulverise the paying punters into a jelly-like paste.


Oh...and feedback.

:D

Cheers,
Tim

[Halsu]

Oh...and feedback.

As far as i know, feedback shouldn't be any bigger problem with LDC:s than with dynamic mics, if the distance between the source and the mic are the same in both cases (naturally assuming the polar patterns and the frequency-response curves of the mics are similar).

I guess using a styrofoam popkiller could take away a lot of the plosives.

[Bob Olhsson]

Some LDCs are lots less likely to pop than others.

I don't think they are appropriate for really loud music but I think loud music style technology and the knee-jerk cranking of everything up to just before it feeds is extremely inappropriate for far too much live music.

[ggunn]

As far as i know, feedback shouldn't be any bigger problem with LDC:s than with dynamic mics, if the distance between the source and the mic are the same in both cases (naturally assuming the polar patterns and the frequency-response curves of the mics are similar).

I guess using a styrofoam popkiller could take away a lot of the plosives.

In my experience LDC's are worse at feeding back than dynamic mics. No mic has a linear response all the way down to minus infinity SPL, and going below a certain SPL (different for different mics), the signal generated by the mic falls off much faster than the SPL. On LDC's that point is lower than on dynamic mics, so they feed back at lower levels.

[since 1982]

Ive never even heard of an LDC mic does any one have any pics or links to an overall description.

Thanks

[ggunn]

Ive never even heard of an LDC mic does any one have any pics or links to an overall description.

Thanks

LDC = Large Diaphragm Condenser. Google it; you'll find lots of info.

[since 1982]

Oh i see LDC... i got lost on the abbreviation. I would defo not be using my LDC's at the venue i was working at on the weekend, scared they would get pinched.

[Halsu]

No mic has a linear response all the way down to minus infinity SPL, and going below a certain SPL (different for different mics), the signal generated by the mic falls off much faster than the SPL.

Okay, so you say dynamic mics have heavier moving elements, thus they don't react as much as LDC:s lighter ones on very low SPL levels, right?

In practice mics have a kind of a built in expander at work at very low levels due to their construction - that actually makes sense.

Thanks.

[ggunn]

Okay, so you say dynamic mics have heavier moving elements, thus they don't react as much as LDC:s lighter ones on very low SPL levels, right?

In practice mics have a kind of a built in expander at work at very low levels due to their construction - that actually makes sense.

Thanks.

That's what I'm saying, yes, but more generally all mics have an SPL threshold below which the signal generated by the mic falls off more rapidly than does the SPL. That threshold is higher for a dynamic mic than for an LDC.

[Mr. dB]

LDC is fun if you have performers who know how to work with it. Like, say, Del McCoury or Gillian Welch & David Rawlins. If you're picking up vocals and instruments with the same microphone, the performers have to know "the dance".