Mic Clipping

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amiller

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How can I tell if I am clipping a mic with too high a SPL? There have been times where I record something through a mixer direct to CDR, never showing signs of clipping with either unit's meters. Later when I look at the audio data in a DAW, the signal appears to be clipped or highly compressed at a level well below the maximum headroom available.

I have only had this experince recording percussion instruments, especially cowbells and woodblocks, but am unsure how to tell when the mics are too close.

Thanks for any help!
 
Listen to a feed from the pre; don't just look at the meters.
When it clips, you'll know!
 
percussion has extreme transients. A peak meter should pick them up but a VU won't. I never peaked a kick above -20 and the same with percussion.
 
I am not sure if we are talking about the same things, but I am talking about distortion induced by overloading the microphone element, and not by having the mixer gain turned up too high. I am trying to figure out how to know when the microphone itself is creating the distortion, by being too close to the sound source.

I have always thought that any type of meter on a mixer would not display this type of distortion, but I am not sure. Any input is greatly appreciated.
 
You know what? I have had the same problem with a mic. The AT4033 actually. Doing vocals. It ALWAYS clips...i have a windscreen and im back about 3 feet sometimes and itll clip when i really belt. I sing more rock but still...its a little messed...im dying to find an answer to...i thought compression before the mic then i hit myself. What the HELL was i thinking. =)
 
Set the input gain on your mixer with plenty of headroom, then listen. If the mixer is at a proper level but the sound is distorted then the problem is probably the cable or mic (possibly bad channel as well).

One other thing, does it sound clipped or just look clipped? Different sounds have different waveforms... the woodblock might have more of a "square wave" than other instruments.

[This message has been edited by pglewis (edited 07-16-2000).]
 
Some mics have a pad switch on the body of the mic,frequently on the order of -10db.This attenuates the signal before its arrival at the mics internal circuitry.If your mic has one,try it and boost the gain accordingly on your preamp.Cheers!
 
<<im dying to find an answer to...i thought compression before the mic then i hit myself. What the HELL was i thinking. =)>>

THAT would be some good engineering. :P
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by John Sayers:
percussion has extreme transients. A peak meter should pick them up but a VU won't. I never peaked a kick above -20 and the same with percussion.<HR></BLOCKQUOTE>
Can u explain this more john ?? cos if your saying that your kicks never rise above -20 then i must really be crossing some boundarys... or am i just full of shit ... please let me know either way !!! cheers
spider
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by KaBudokan:
<<im dying to find an answer to...i thought compression before the mic then i hit myself. What the HELL was i thinking. =)>>

THAT would be some good engineering. :P<HR></BLOCKQUOTE>

Nah. It's called good microphone technique.
Look at the pros how they pull the mic away when they sing loudly!
 
i have trouble with saturating the element in my mics as well. on my audix om-3xb's (great mics, IMO-transience astounds me every time, for a dynamic), which are rated to 144db spl, when i really belt it out, i saturate the mics, even at 3 feet(also with the windscreen on). what i had to do was actually pull back 3 feet AND hold a cd jewel case a few inches in front of my face to keep it from clipping-and even then, it was still close. i have an unusually loud voice when i kick it up a notch, though. it sounds pretty cool that way, actually-not only is it still nice and loud, but there's a kind of presence/reverb added on since the mics have to pick up a great deal of sound from reflections in my room. i find that when playing gigs, i tend to have trouble not saturating the system as well, but it seems to impress the audience, so i guess it's not so bad ;)
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Spider:
Originally posted by John Sayers:
percussion has extreme transients. A peak meter should pick them up but a VU won't. I never peaked a kick above -20 and the same with percussion.<HR></BLOCKQUOTE>
Can u explain this more john ?? cos if your saying that your kicks never rise above -20 then i must really be crossing some boundarys... or am i just full of shit ... please let me know either way !!! cheers
spider
Click to expand...

There are two kinds of meters - VU (Volume units) and Peak (Peak waveform meters) The volume unit meters are dampened and don't give an indication of the transient peak. If you peaked a kick drum to zero on a VU meter the transient peak would be hitting +20db or something like it yet the tape overloads (Saturates)at around +14db.(On a high quality 2" machine - a tascam cassette recorder will saturate at much lower) The tape will play it back for a couple of days but eventually the magnetism dissipates and the attack goes out of the sound - hence the expression it sounded great when I recorded it but now it sounds flat and lifeless. It is the transient peak that gives percussion and drums their attack and clarity.(Which is why I said overcompressed drums sound like shit in another post) When you use a peak meter it should show you the top of the transient but most cheap meters don't have a fast enough rise time to allow this therefore it is advisible to back off just in case. If you saturate Digital you will know about it cos it's pure distortion. When people talk about tape saturation this is what they are talking about - some people like the sound that saturation creates cos it's louder yet softer hence the computer simulators that supposedly emulate the effect. Tambourines and percussion are extremely transient and will overload your system easily if you don't have fast rise time metering.
Hope this helps
cheers


[This message has been edited by John Sayers (edited 07-18-2000).]
 
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