try to fix "buzzy" dialog

JHendrix2 wrote on 9/30/2013, 8:28 AM
I know you cant fix clipped dialog but this has always driven me crazy. what I mean is when I use the SENN lav mics the audio comes in, not clipped, (in fact the input is always well below clipped) but on strong passages (on some voices) the voice sounds tinny or buzzy - as if it was clipped. must just be bad mic quality - but is there any way to make it less buzzy?

Comments

rs170a wrote on 9/30/2013, 9:10 AM
What model of Senn lav are you using?
What kind of speakers are you using in your edit suite?
Can you post short WAV files for us to listen to (good and "buzzy")?

Mike
JHendrix2 wrote on 9/30/2013, 10:06 AM
ew100 G2
Alesis M1 Active

http://mfi.re/listen/t4lsn9kz3dfi2x1/dialog.wav

this file has both good and buzzy

--

and here is the 'cam mic" version...i considered to try and use this but was not able to get rid of 'boxy" sound

http://mfi.re/listen/gxrv4l2f1xif617/dialog-cam-mic.wav
eightyeightkeys wrote on 9/30/2013, 11:03 AM
iZotope RX3 audio restoration plug-in. Expensive but if you really need it fixed, then this is the one.
johnmeyer wrote on 9/30/2013, 11:14 AM
This is the result of using the RX3 declip function:

Dialog (declipped)

The problem sounds like you might have had a dead battery. Does the mic use a battery, or does it need phantom power (or not need phantom power, but it was being supplied)? It could also be too hot, but I think you said that wasn't the case.
JHendrix2 wrote on 9/30/2013, 11:27 AM
I have RX2 but I have tried to use it before and have zero clue how to use it. Wow, your fix is great, can I do that in RX2?

(mic uses battery but i have found those small mics just get buzzy even in a slight pre-clip state..well, at least compared to a shotgun that is. anyway, you can see the waveform and it looks 'sort of" clipped)
johnmeyer wrote on 9/30/2013, 11:35 AM
I have RX2 but I have tried to use it before and have zero clue how to use it. Wow, your fix is great, can I do that in RX2? Yes, the regular (i.e., not the advanced) version of RX2 has exactly the same declip module (I don't think this was improved or modified in RX3).

You first must normalize or increase the gain of your file so that the peaks are above -6dB. Then, set the clipping threshold so the red line showing the threshold is a 2-3 dB below the peaks. Everything above that line will be treated as clipped, and everything below the threshold will be left alone. You then adjust the makeup gain so the final result has roughly the same peak levels as the original. You can choose the quality of the algorithm. It does make a difference, but the higher quality doesn't always produce better results. Many years ago I had an email exchange with the guy who designed it. I kept getting weird results with the "high" quality setting (and I still do) and he advised me to try the lower quality settings.

With your file I had to process the opening statement separately from the rest of the file because the "makeup" audio gain had to be set really low for that section.
JHendrix2 wrote on 9/30/2013, 11:44 AM
awesome many thanks , I will give it a shot.

Are you sating I should run "Normalize" process in SF first then Run RX? Or are you saying I should use the RX 'makeup gain" as a Normalizing function?
johnmeyer wrote on 9/30/2013, 12:05 PM
Are you sating I should run "Normalize" process in SF first then Run RX? Or are you saying I should use the RX 'makeup gain" as a Normalizing function? You have to increase the volume, which doesn't necessarily have to be the Normalize function, prior to running the declip module. This is done in order to get the clipped peaks up into the range where the declipper can work. The alternative is to reduce the clipping threshold down to really small values, but the algorithm isn't really designed to work with low-volume audio, partly because true clipping is usually caused by some sort of overload condition.
rraud wrote on 9/30/2013, 12:30 PM
Yoru clip sounds like preamp overdrive, either from improper settings on the wireless or the camera's input stage. De-clippers usually work fairly well on occasional digital 'overs', so your mileage may vary using them. Along with some EQ and other processes, it may be 'salvageable', but don't expect miracles to happen.
rs170a wrote on 9/30/2013, 12:54 PM
Apologies for not replying sooner but I got tied up at work.
rraud's suggestion about improper settings is definitely one to look at as wireless overload was my first thought when I listened to it.
I got a G3 kit about a year ago and spent a lot of time playing with the different transmitter & receiver gain settings until I was happy with the results.

Mike
JHendrix2 wrote on 9/30/2013, 12:56 PM
Regarding just the opening part. How much did you boost it using what, and what setting did you use on declipper?

Here is what I got so far...not that bad:

http://mfi.re/listen/xk891zcl9wx9bsm/dialog_Take_2.wav
JHendrix2 wrote on 9/30/2013, 2:16 PM
Yes thanks guys, when i set the levels I was only looking at the meter on the camera, so it could have been hot on the transmitter and delivering a too hot signal even if the signal was low.
mudsmith wrote on 9/30/2013, 2:33 PM
That is the essential, added problem with wireless: You can be clipping the preamp (at the transmitter) even if the level is set at the receiver and/or camera to a "normal" level. Safeguard is always the same: listen to the signal coming in to the camera or recording device.....but setting the transmitter conservatively to begin with can help avoid the problem as well.

Not having a dedicated audio person, as is too often the case these days, leads to this situation.
rs170a wrote on 9/30/2013, 2:38 PM
From the QuickStart guide for my G3 system:

It is suggested that you adjust the receiver (EM or EK) AF OUT setting to around 0dB for most situations. The AF OUT setting is your master output volume.
The SENSITIVITY setting (SK and SKM transmitters only) should be adjusted so that in your loudest passages, the AF PEAK indicator briefly illuminates. As the SENSITIVITY settings move closer to “0 dB” they become louder.

Mike
farss wrote on 9/30/2013, 3:38 PM
I've found the G3's with the MEK2 Gold mics need to be set to -9dB for typical speech and mic location.
The stock mic that ships with the kit maybe a little different although a I don't recall it being much more or less sensitive.

Certainly transmitter preamp overload or transmitter over modulation (no way to know which it is really) is a problem that needs to be wrangled. Once that's setup correctly I've found that if the transmitter is being fed into the typical camera's microphone input then setting the receiver's output to -18dB works well.

In theory one can set the camera's audio input to "Line" for better gain staging however then it's hard to get a good level into the camera from the receiver even with the output set as high as it will go.

The G3 systems is certainly capable of delivering good results. If you're getting results that immediately have you reaching for Rx or having to futz around with the sound quality a lot you are setting up something wrong on the G3 system. Getting that sorted will be more rewarding than trying to fix the recorded audio.

Bob.