Audio Peaking question (newbie)

DeanFS7

DeanFS7

Active member
Hello all, something that's baffling me a little. I am new to manually setting audio (I use a C300 MKII and have a Sennheiser MKH 8060 Short Shotgun Microphone on it) and would love some help! Recording some audio from a bands soundcheck today I checked my levels and I was at around -18db on one and peaking at around -6db on the other channel yet the sound is clipped still. Is there a setting I can use that will stop this? Many thanks for your help!
 
Clipping can happen anywhere in the chain. So the levels may be beyond what the mic can handle. If that is the case levels after that don't really make a lot of difference. A roll off won't help if the mic is clipping so the first thing to look at is how loud VS what the mic can handle. As a general rule dynamic mics can handle a lot higher levels than condensers. So if it's a loud rock band you may need to get a mic that can handle the volume.

The other thing not quite clear from your post is, sound checks are generally at a lower level than performance. If you set levels at sound check and the performance was clipped it's quite probable that the problem is that the performance was a bunch louder than the check. If the check is what clipped then I put money on the mic not being able to handle the levels.
 
It's also possible to clip the mic pre inputs. Not sure of your camera so? The mic is rated at 129SPL so ???? Probably not clipping the mic, though still possible. As SM58 is around 160 SPL, but pain is around 140 SPL. It's logarithmic so 140 is a LOT louder than 129 but still over 129 would be extremely loud.

The other thing is that human hearing tends to clamp down when faced with really loud sounds so it's possible that the "clipped" sound is how it actually sounds and your ears are "softening" it because it is too loud for them to handle.
 
Probably overloading the mic head amp as this mic is a condenser and quite sensitive and a band will be kicking out a high level of bass etc.

Certain mic's have a -10db pad selectable to reduce the gain going into the mic head amp but a dynamic mic would probably be a better choice to record such high levels.
 
GaryNattrass said:
Probably overloading the mic head amp as this mic is a condenser and quite sensitive and a band will be kicking out a high level of bass etc.

Certain mic's have a -10db pad selectable to reduce the gain going into the mic head amp but a dynamic mic would probably be a better choice to record such high levels.
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Thanks everyone. I'll play a bit today. I had trimming at -12DB with the limiter on and attenuator off. Still not 100% sure what they all really mean if I'm honest. I've a lot to learn. Will play around with these settings today and listen through my in ears.
 
It could also be that even though the levels on the meters look OK that the mic amps or level control in the camera are overloading due to the high output from the mic, may be worth trying an XLR in-line -10db pad to see if that helps.

Also you mentioned the attenuator on the camera, try that too as it will limit what is being presented to the limiter and mic amp stage in your camera.
 
GaryNattrass said:
It could also be that even though the levels on the meters look OK that the mic amps or level control in the camera are overloading due to the high output from the mic, may be worth trying an XLR in-line -10db pad to see if that helps.

Also you mentioned the attenuator on the camera, try that too as it will limit what is being presented to the limiter and mic amp stage in your camera.
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Having the attenuator on worked. Audio sounds great. Thanks for your help guys.
 
Peaks of -12dB fs is quite high. -6dB fs is where I set my limiters. If you were using those as averages, I would expect extreme clipping.

dB's are hard to understand, mainly because it is only a scale until something else is added and the scale can start about anywhere. BUT, I assume you are only worried about dB fs (a digital measurement) in your case. With 24bit sound normal peaks should be around -20dB, and extremes may hit -6dB, above that is BAD.

Clipping at the mic is also BAD. But since your attenuator worked, it does not seem like that was the problem.

BTW, in dB fs (deciBels full scale) the scale starts at the point where the signal is the maximum possible that digital can handle and goes down from there. There is nothing above 0dB fs, so it is very important to stay away from it.
 
graywolf said:
Peaks of -12dB fs is quite high. -6dB fs is where I set my limiters. If you were using those as averages, I would expect extreme clipping.

dB's are hard to understand, mainly because it is only a scale until something else is added and the scale can start about anywhere. BUT, I assume you are only worried about dB fs (a digital measurement) in your case. With 24bit sound normal peaks should be around -20dB, and extremes may hit -6dB, above that is BAD.

Clipping at the mic is also BAD. But since your attenuator worked, it does not seem like that was the problem.

BTW, in dB fs (deciBels full scale) the scale starts at the point where the signal is the maximum possible that digital can handle and goes down from there. There is nothing above 0dB fs, so it is very important to stay away from it.
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The first sentence I am confused by. If peaking at -12 is too high then why would having limiters at -6 make sense. -12 is around 1/4 the level of -6.

I would also consider your levels quite low. Peaking at -20 is very low. For concert recordings I aim at peaks just below -3dB fs. Average levels are very dependent on the style of music so they might be anywhere from "too high" to "too low" by normal production standards.

If I didn't have really good limiters I would probably aim at peaking at -6 dBfs just to be safe. The only time I would set a level as low as you are is if I knew or suspected that there would be an actual peak way above what the sound check / rehearsal etc. produced. And those times do come up but if your real peaks are only at -20dBfs then anything quiet is getting down in the mud, IMHO.

I would add that while I agree with the stay away from zero I also try to never get above -3dBfs since you can get 3dB of overshoot in the D/A converter and get a roughness to some of the high frequencies.
 
Noiz2 said:
The first sentence I am confused by. If peaking at -12 is too high then why would having limiters at -6 make sense. -12 is around 1/4 the level of -6.
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Got to read what I wrote, not what you think. I said, if he was using those as averages, his peaks would be too high.
 
He never posted anything about averages, he said he was peaking around -6. One could read his "I was running about -18" as a average I guess but that would be a "normal" average.

But I agree with your assessment if he was averaging -6 it would be a mess.

Seems it was a preamp overload so the levels he was setting didn't end up being the issue in the end.
 
The Canon cameras are easy to overload the preamp on the XLR input. A setting of 5 on the audio dial seems to be zero gain for both mic and line input gain. If the setting is much below 5, you won't even be able to hit 0dB as it will saturate the preamp before you ever clip the digital input. This can result in you thinking that you have perfectly decent levels based on the fact that you aren't close to clipping on the meters, but having bad distortion in the audio. Best practice is to never go below a setting of 5 on the input and adding attenuation either in the menu or with a pad if your levels need to be brought down to avoid clipping.
 
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