Mic distortion

[Fidelity Castro]

I have produced a fair bit of music for large groups of players, typically incorporating a mix of electronic and acoustic instruments: keyboards, electric guitars, saxes/woodwinds, brass, percussion. Everything is played live and electronic instruments are all individually amped to maximise spatial separation and also for the character of overdriven amps. The music itself is loud, intense with subtle shifts of timbre and harmony over long periods of time.

As you can imagine recording is quite tricky. When recording live shows, I usually use 1-2 portable DAT recorders with 2-4 mics placed at various points around the room. The different mic recordings are then lined up in protools and mixed together according to what sounds best, with minimal compression and EQ.

A problem I have come across more than once is what has been described to me as "mic distortion". Basically it sounds like very subtle clipping that crops up only at the very loudest or densest points, even though the signal itself is not in the red.

Can anyone explain what this phenomenon is? Is it be density- or volume-related? Or both? Or is it related to the mic itself? Diaphragm size?

Any ideas welcome

 

[SouthSIDE Glen]

Often it's just too much volume, plain and simple. A band that I regularly work with live has a drummer with a standard SM58 vocal mic. This guy plays LOUD - but extremely well...the best drummer I have worked with, but damn he's loud . He has an almost stronger and louder voice: imagine someone with the pipes of Luciano Pavoritti wailing and belting it out like Al Green on steroids. Not a gig goes by that this guy does not regularly send his microphone into distorted overdrive that sounds like an old ceramic microphone run though heavy tape saturation. (And no, it's not the preamp; the mixer is set well within levels.)

G.

 

[Fidelity Castro]

Wow. So do you overcome this by just turning down the input level?

 

[surfmaster]

it sounds like you would need some sort of pad, but that would be complicated in your type of mobile set up. i know mshilarious sells in-line 20db pads that keep your mic from overloading and they would just require another cable for each mic you use a pad on. you could try those.

 

[SouthSIDE Glen]

A pad does no good; the microphone itself is saturated.

And no, it's not a bad microphone, I've tried a couple of different 58s and a beta58. The beta is not quite as bad, but it still happens. Cardioids like a 57 suffer from proximity with his voice and technique.

This guy is built like a football player, about 6' 4" tall, with the build of a linebacker (he actually playes ice hockey; I'd rather fall on a grenade than be checked into the boards by this guy. .) He is a fantastic drummer in ever respect; he's not a cymbal basher, he's technically as proficient as it gets, and he has the complex musical theory of anyone who's been a pro in the business for 30-odd years. And he's really fun to listen and play to.

But he just has a lot of mass behind him. It's not like he's swinging his sticks like a Space Odyssey ape with a hippo bone; it doesn't look like he's hitting the skins hard at all. He's just strong and solid and LOUD. Add in his great voice and his swallowing of the mic and he's probably pushing 135dBSPL at the wind screen.

We just live ith it. Frankly, I'll bet the audience never even notices the saturation - hell by the thrd set they're lucky if they recognize the person they came there with. And even to those of us who listen for such things and who do notice it, it just sounds like Little Richard hollerin' into a 55SH, which ain't that bad a thing.

G.

 

[RAK]

Could be something finicky with the DAT recorders. When it doubt blame the DATs anyway right?

 

[xstatic]

Honestly, I would investigate the DAT players. While it certainly is possible to to overload at the microphone itself, it is extremely unlikely to happen while recording with ambient mics like it sounds like is the case here. In order to distort one of those you would really need to have some extraordinarily painful volume levels in the house. I have run some excruciatingly loud shows before, but none of them have even come close to the 140+ db's it would take to do what is described here. It is important to also remember that preamps can distort in certain frequency ranges without metering red. The first cause would be a spike that wa too quick to meter, although this would be an audible thing during the performance. The second would be a continual frequency that is cutting through enough on the mic, but further from the meters responsive range. Peak metering would reveal this better than one of the various types of RMS metering. Also, if there is an option, make sure the meter is set to respond as quickly as possible. You also may have meters that are out of alignment which are resulting in false levels.

 

[Fidelity Castro]

All very helpful - thanks.

Certainly could be the DATs. There are definitely constant frequencies. I set the record level during rehearsal and like to get as loud as possible a signal, but am probably not conservative enough, considering players usually get a bit more carried away in performance.

 

[bennychico11]

don't forget guys...preamps distort too.
I've come across more preamps that distort first before any microphone. So, my guess would be it's the preamp...and in this case a pad between microphone and preamp would indeed help. Whether you do it with a pad device between mic and DAT or with a pad switch on the DAT.

 

[xstatic]

After the original posters last post, I would say it is most likely the preamps or the digital level. It is very important to leave LOTS of headroom if you are just setting your level during soundcheck or rehearsal etc... I have had many many bands tell me that they are playing louder than they ever will play during a soundcheck. First song out the gate they are almost always MUCH louder than what they had previously said would be their loudest.

 

[cello_pudding]

After the original posters last post, I would say it is most likely the preamps or the digital level. It is very important to leave LOTS of headroom if you are just setting your level during soundcheck or rehearsal etc... I have had many many bands tell me that they are playing louder than they ever will play during a soundcheck. First song out the gate they are almost always MUCH louder than what they had previously said would be their loudest.

haha...too true.

PLAY LOUD!! i say...I AM!!...they say



and then during tracking...they clip constantly.

i say to fix mic distortion, tell the singer on the loud parts...back off the mic a whole lot. that's the only thing you really can do

 

[SouthSIDE Glen]

I have had many many bands tell me that they are playing louder than they ever will play during a soundcheck. First song out the gate they are almost always MUCH louder than what they had previously said would be their loudest.

And it gets worse after that even. I think it's an incontrovertable law of nature that the band gets louder every set.

G.