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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Distorted audio

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david_winters

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I'm consistently getting distorted audio and yet the waveforms are far from clipping. My location sound guy says he's not hearing the clip E-E headphone out while recording, only during playback. Then we are screwed in post.

On this shoot the setup was boom mic into - mackie mixer XLR line level out - Red input set to line level.

Attached is an extreme example. AIFF was created in QT as a direct export from a QT proxy.

What is going on here?
 
thats interesting ... it could be the line out on the mixer ... (too much is coming on ... then the master-fader is drawn down... and so you have an "clipping" sound without clipping.

have you tried an other line out (please give me the "Name" of the mixer ... mackie has several series ...)

it could be an +4 / -10db selection-probelm, as well.
 
sorry, i checked again on soundtrack pro ... actual, the waveform is clipping ... so it's definitely too much gain on the master lineout !
 
The confusing thing is my sound guy, Daniel, is not hearing any clipping while recording. This is from monitoring the headphone out on the cam. Also the camera level meters never come close to clip while recording. I'm going to get Daniel to followup here.

Thanks for the help.
 
The example I posted is the most extreme take, deeper pitched (male) voices appear to exaggerate the issue. Other actors don't clip as frequently.
 
ok ...

thats complex:

you have several sources of error...

can you plug the mic direct at the RED ... so you can test/check the RED Inputs ...
(i know thats not the line-in singal ... just testing, somtimes you dosn't know ...)

can you listen to the mixer-headphone-out ...

reduce the mic gain ... (an the master as well ... you have some "back up" i think its too "loud" anyway)
 
Michael P. Schmidt said:
reduce the mic gain ... (an the master as well ... you have some "back up" i think its too "loud" anyway)
Click to expand...

usual your master-levelmeter for voice-recordings needs to be around -10 /-12 db so you have some headroom ... (if the mic & voice is a good one)
 
david_winters said:
The example I posted is the most extreme take, deeper pitched (male) voices appear to exaggerate the issue. Other actors don't clip as frequently.
Click to expand...

yeah ... that's because he has an solid voice ... more "air is moved" so he is "louder" and stronger
 
audio

audio

i wasn't there the day of the shoot with the deep voice, loud guy...so there could be quite a few things going wrong there. however, on other shoots we're having a bit of the problem described.
all is well on the front end. using a 1202, trims aren't too hot, faders aren't too hot, and i pull the mains way down for this camera (as compared to sdx900 or comparable). last time i did a shoot with this camera the meters looked fine but the record level was way too low due to having the setting at -10 on camera. this time they looked about the same but the levels are too hot. pretty ridiculous that the meters looked the same but the record level was so vastly different...i hate the RED's meters. also, makes no sense that audio on the RED behaves so much differently than on other cameras.
 
hmm... thats mysterious ... i think you did nothing wrong (sounds everything right to me)

so, probably something is wrong with the RED-LineIn ...

it sound to me if there is too much gain comming on at the "RED-side"

do you use the balanced XLR outputs or the balanced/unbalanced at the top of the mixer ?
whats with the "MAIN OUTPUT LEVEL" switch on the rear of the mixer ?

whats with the "RED direct-mic-conection" - have you tried that ?

have you tried a second RED ;)

whats with an other mic

whats with an other mixer

have you tried to connect a CD-Player or something like that (an other lineout-source)

...

you are right, there could be quite a few things going wrong here.
probably u have to call your RED-Support ;-)
 
yeah, it's kinda weird. i use the XLR outs of the mixer and have them set to output line level with camera set to 0db line level. if i bring levels on my mixer up to U the camera is in hardcore redline. with my mixer meters at about -20 things start hitting orange.
i've plugged a mic directly in before but i can't remember the results.
i guess we should plug some stuff line devices straight in and see what happens.
 
Michael P. Schmidt said:
hmm... thats mysterious ... i think you did nothing wrong (sounds everything right to me)

so, probably something is wrong with the RED-LineIn ...

it sound to me if there is too much gain comming on at the "RED-side"
Click to expand...

We've been dealing with this situation for months, with still no real solution offered to rectify the problem.
This condition began with the audio board upgrade. Build 17 resulted in recordings being made that were 10db too hot.
Beta 18 changed things a bit, we're now only 7db too hot.
The best thing to do is test, extensively, right in to your post environment to find a gain structure that is acceptable.
Hopefully release Build 18 will correct this.
 
Daniel Powell said:
if i bring levels on my mixer up to U the camera is in hardcore redline. with my mixer meters at about -20 things start hitting orange.
Click to expand...

ok here we go... indeed, it seems like an "Input sensibility trouble"
u really have to check the RED audiosetting ... and try other signal sources, as well
 
I'm having the exact same problem. This is really frustrating. I had great audio on the previous audio board - consistently. Now with the new board I have lost some great audio and this is proving a real pain in post. I want my old board back - maybe it was build 15. Don't know. After the board upgrade they also automatically upgraded my firmware from 15 to 17.
 
... i'm not a RED owner :( ... so u have to help me out ...
there was an real physical change going on ? ... a new audiochip or just an "audio-firmware-upgrade"?

so it's kinda warranty-matter (probably)
 
plugged camera and everything in to check different settings and here's what i found:

build 18 v3.6.0

as pointed out before by myself and Burke, it is impossible to line up your meters on your mixer to the meters on the RED. the camera picks up the signal at least 7db hotter than what the mixer is putting out, maybe more (i'm just doing observational tests).

also discovered that plugging the mic in directly and using the 48v phantom power doesn't work.
conducted this test:
camera ch 1 set to line, 0db. ch 2 set to mic, +48v.
mic to mixer, mixer plugged to channel 1 audio to camera no probs (except the mismatch levels of course). i'd pull the mic and plug to channel 2 and it would work for about 3 seconds then fade out.

strange eh?
 
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