Help...@(#)@(# recording problems.

[BigRay]

I recorded a monteverdi piece tonight(marienvesper)

40pc choir, 50pc orchestra



U87s(A-B), and MG 200s.DIN

mic into wendt x4>>>line out to MYtek stereo 192...AES out to SD 722


well...every time I even raised the volume EVEN SLIGHTLY when the singers were singing..I got this crackling noise...sounded like overloading sorta..snap crackle pop.....but the levels werent even anywhere NEAR overloading..when the instruments played alone it was fine..but if say the choir was singing a moderately loud passage..forget about it. again..this crackle(for lack of a better term) seemed only to present itself when the singers were singing...not on instruments....possible to brick wall even though levels are nowhere near peaking???it was very frustrating...couldnt even raise it barely above a whisper....any thoughts??maybe the mics cant handle choir harmonics???man i am upset!

i have another chance tommorow night.I do notice when i run preamps into the mixer instead of going mic in to the mixer...it doesnt seem to happen as much...maybe a correlation between going MIC IN and LINE OUT??

man. this sucks.

 

[BigRay]

heres a sample...

http://s46.yousendit.com/d.aspx?id=37TAVRWTM87YH177J85KURK5LU

 

[dgatwood]

I recorded a monteverdi piece tonight(marienvesper)

40pc choir, 50pc orchestra



U87s(A-B), and MG 200s.DIN

mic into wendt x4>>>line out to MYtek stereo 192...AES out to SD 722


well...every time I even raised the volume EVEN SLIGHTLY when the singers were singing..I got this crackling noise...sounded like overloading sorta..snap crackle pop.....but the levels werent even anywhere NEAR overloading..when the instruments played alone it was fine..but if say the choir was singing a moderately loud passage..forget about it. again..this crackle(for lack of a better term) seemed only to present itself when the singers were singing...not on instruments....possible to brick wall even though levels are nowhere near peaking???it was very frustrating...couldnt even raise it barely above a whisper....any thoughts??maybe the mics cant handle choir harmonics???man i am upset!

i have another chance tommorow night.I do notice when i run preamps into the mixer instead of going mic in to the mixer...it doesnt seem to happen as much...maybe a correlation between going MIC IN and LINE OUT??

man. this sucks.

Sounds like you're clipping on the mic preamps in your board. There's two separate amp stages happening, one at the input (generally adjusted by a trim pot up near the top edge of the board), and one at line level in the rest of the board. Your main fader is between these. If you just turn down the main fader, you can still saturate the preamp stage.

In fact, depending on the preamp design, with extremely loud sources, it can actually be possible to saturate the preamp stage with the trim pot all the way down. In the unlikely event you run into this, either move the microphone farther back to reduce the level or add an inline pad between the microphone and the mixer.

There's also the narrow possibility that if you are using a lousy mic, you might get distortion there.

Check the volume all the way through your signal chain. Sing a note loudly enough close enough to the mic to get distortion. Turn the trim on your board all the way down. Next, set the faders on the board to unity gain (0dB). At this point, your computer's level should roughly match the level shown on your board. You should not get distortion until your board is in the red.

When you actually go to record, it would be nice if you could get a level check ahead of time, say during a warm up before the house opens. If so, you want to set everything on unity gain, then turn up that trim pot for the preamp's input gain until your levels are reasonable. If they are reasonable to begin with, leave that preamp gain trim pot all the way down.

As a sanity check, you might have them sing their loudest passage, then turn up the preamp gain until you hear distortion and/or you see a clip light on the board. Mark that spot and make sure that no matter what you don't come anywhere near it... like say half that far up.

Another thing that can cause problems is a lousy headphone output on a mixer making you think you're getting distortion when none is present, and/or lousy headphones doing the same. Make sure there's really a problem.

EDIT: I listened to it. It doesn't sound quite like the distortion I'm used to. It sounds like a $#^*&^@$ wireless mic losing the signal. Any chance you have problems with bad cable connections getting bumped around?

The odds are pretty good that it's a gain staging problem, as I said earlier, but it does sound a little weird....

Nice choir, BTW.

 

[BigRay]

Well I figured it out. The guy who sold me the mixer had the same problem going mic in to the mixer.Some mics simply overload the op-amp chip in the unit. The only way around this is to reduce the sine wave (signal) before it gets to the chip, then raise it later.There are 20db attenuators on the mixer, which I shouldve engaged. Ill run it tonight with the attenuators, and hope for a good outcome. Reason tells me to just ditch the mixer and external adc and run a stereo pair into the recorder ...but i like living on the edge..

Thanks so much Dgatwood.

Teddy

 

[Richard Monroe]

"Reason tells me to just ditch the mixer and external adc and run a stereo pair into the recorder"

I can see the lightbulb over your head, Ray. You're not running enough mics to require a mixer, so why mess up your gain staging with a dodgy opamp? Shorten your signal chain.-Richie

 

[BigRay]

given the fact that I am running 4 mics and my recorder has two inputs..a mixer is necessary. I just needed an attenuator in the path, now it sounds great.

"Reason tells me to just ditch the mixer and external adc and run a stereo pair into the recorder"

I can see the lightbulb over your head, Ray. You're not running enough mics to require a mixer, so why mess up your gain staging with a dodgy opamp? Shorten your signal chain.-Richie

 

[Richard Monroe]

Sorry, Ray, I guess I didn't get your shorthand. The only mics I see in your signal chain is a pair of U87's. I do see the X4, but it's not clear to me where the other 2 signals are coming from unless you're using 2 coincedent pairs of U87's. Sorry if some of your designations are out of my league. Any way, I'm glad an attenuator solved the problem. I listened, and also heard clipping, but wasn't familiar enough with your shorthand to begin to diagnose the gain staging problem.-Richie.

 

[dgatwood]

Sorry, Ray, I guess I didn't get your shorthand. The only mics I see in your signal chain is a pair of U87's. I do see the X4, but it's not clear to me where the other 2 signals are coming from unless you're using 2 coincedent pairs of U87's. Sorry if some of your designations are out of my league. Any way, I'm glad an attenuator solved the problem. I listened, and also heard clipping, but wasn't familiar enough with your shorthand to begin to diagnose the gain staging problem.-Richie.

If I had to guess... one coincident pair for the orchestra and a separate pair for the choir.

 

[BigRay]

U87s(A-B), and MG 200s.DIN

Shorthand??
U87s and Microtech Gefell 200s DIN

Sorry, Ray, I guess I didn't get your shorthand. The only mics I see in your signal chain is a pair of U87's. I do see the X4, but it's not clear to me where the other 2 signals are coming from unless you're using 2 coincedent pairs of U87's. Sorry if some of your designations are out of my league. Any way, I'm glad an attenuator solved the problem. I listened, and also heard clipping, but wasn't familiar enough with your shorthand to begin to diagnose the gain staging problem.-Richie.

 

[BigRay]

If I had to guess... one coincident pair for the orchestra and a separate pair for the choir.

]

you are right Sir.

I didnt know I was using shorthand...MG is a pretty common microphone manufacturer, as far as I know...??

color me confused.

 

[Richard Monroe]

MG is also a designation for a series of Yamaha mixers, and a British apirts car, and a lot of other stuff. Frankly, I've never seen Microtech Gefell abbreviated in that way, but it's no big deal. I was just trying to understand your signal chain. Thanks for the clarification.-Richie

 

[BigRay]

My mistake Sir. My apologies for being vague...I really appreciate the help.

Teddy

MG is also a designation for a series of Yamaha mixers, and a British apirts car, and a lot of other stuff. Frankly, I've never seen Microtech Gefell abbreviated in that way, but it's no big deal. I was just trying to understand your signal chain. Thanks for the clarification.-Richie