Binaural bass crackling: How to fix/avoid?

[Micky Hulse]

Hi,

I recently purchased some Binaural headphones and I noticed that deep bass will cause what sounds like a crackling noise during the bass sounds.

I am using an R-09 and an MM-BSM-8 "Sennheiser".

The crackling really put a damper on one of my last audio captures... I think these were my R-09 settings:

AGC = On
Low Cut = On (it could have been off)
Plug-in power = off
Mic Gain = H (it could have been set to "L")

Any tips as to what could be causing the crackling noise?

Would low cut on/off cause this problem? Maybe a combination of AGC and Low Cut? Maybe the mic gain?

Thanks!
Micky

[Steve House]

Without a sample it's hard to say just what is going on but "crackling" on loud bass is very often a sign of clipping somewhere in the recording chain. For a variety of reasons, somewhere something is being driven beyond its maximum capacity.

It appears the mics in your setup need plugin power so that should be turned ON.

AGC leads to "pumping" where the gain is turned up when things are quiet as it looks for sounds that aren't there. When sound suddently appears, like a song starting, the gain is all the way up and has to be clamped down to normal levels again, which takes a few beats. The high gain could mean the initial sounds are recorded so loud it is driven into clipping until the level is pushed back down again. Turn AGC OFF.

Low Cut reduces low bass response ... experiment

It appears you don't know or pay close attention to the setting that is most important in controlling clipping, whixh is the mic gain setting. Pay closer attention and again, experiment. The correct setting depends on the loudness of the sounds you want to record and the sensitivity of the mics you're using.

Finally, you didn't say what your recording format was but FYI, MP3 is a distribution format, not a recording format. If you care about the sound quality, record to uncompressed WAVE files and convert to MP3 later after editing.

[Micky Hulse]

Hi Steve! Many thanks for your help, I really appreciate it! :)

Originally Posted by Steve House

Without a sample it's hard to say just what is going on but "crackling" on loud bass is very often a sign of clipping somewhere in the recording chain. For a variety of reasons, somewhere something is being driven beyond its maximum capacity.

Ah, very interesting!

That is a good thing to know, because I was kinda worried that it could have been a physical problem with the microphones and/or cabling.

So, in other words, it sounds like user error vs. a physical problem with equipment.

Sorry that I did not provide a sample... I will post a sample as soon as I get home later today.

Originally Posted by Steve House

It appears the mics in your setup need plugin power so that should be turned ON.

Doh! I forgot to mention that I am using a mini battery pack:

MM-CBM-Mini

To be truthfully honest, I don't even know how to open this sucker to replace the 3- 3volt lithium batteries. Hmm, do you think the battery pack could be the problem?

I don't think my audio levels were clipping during record, and they look good during playback on my computer.

I wonder if I need to spend more money on a better battery pack? There are others on this page:

Battery Filter Modules (Stereo)

Or, should I ditch the battery pack altogether and use plug-in power? The only reason why I got the battery pack was to save the battery life on my R-09.

Originally Posted by Steve House

AGC leads to "pumping" where the gain is turned up when things are quiet as it looks for sounds that aren't there. When sound suddently appears, like a song starting, the gain is all the way up and has to be clamped down to normal levels again, which takes a few beats. The high gain could mean the initial sounds are recorded so loud it is driven into clipping until the level is pushed back down again. Turn AGC OFF.

Great advice! Thanks for explanation too!

I normally try to shoot/record all manual when working with video/audio, but I was nervous that I would clip and I was not able to ride levels during this last record session (vacation in S.F., and I had the R-09 in my camera bag with headphones on while I took pics). On the other hand, I had a friend tell me to record at a lower level and then, if I need to, boost audio levels in the editing application.

Either way, I am turning AGC off from this point forward.

Originally Posted by Steve House

Low Cut reduces low bass response ... experiment.
It appears you don't know or pay close attention to the setting that is most important in controlling clipping, whixh is the mic gain setting. Pay closer attention and again, experiment. The correct setting depends on the loudness of the sounds you want to record and the sensitivity of the mics you're using.

Thank you for more excellent and pro advice!

I think the reason why I can't remember if low cut and gain were on/off was because I was recording for hours and remember flipping these settings on/off a few times... Unfroturnately, I don't remember when I changed these settings on the R-09. :(

Originally Posted by Steve House

Finally, you didn't say what your recording format was but FYI, MP3 is a distribution format, not a recording format. If you care about the sound quality, record to uncompressed WAVE files and convert to MP3 later after editing.

Doh! Sorry about that. I was recording at the highest quality setting possible. I am amazed at how much an 8gb memory card can hold... It seemed like the R-09 lasted all day. :)

Thanks again Steve, I really appreciate your pro help!

I will post an audio sample later today.

Have a great day!

Cheers,
Micky

[Steve House]

Just a couple of note ... haven't used either of your pieces of equipment so my previous post was based on general knowledge, in other words, an educated guess. "Crackle" is often clipping and it can occur even if levels look normal, depending on where it happens. Take a look at the waveform in your computer - if the peaks are flattened off like a plane has been run across them, that's clipping. Damaged hardware is another possibility but I'd look to clipping first. Which headset do you have, the standard version or the deluxe version with the ME-2 mic capsules?

[Micky Hulse]

Hi Steve! Sorry for my late reply... Work has been kicking my butt for the last day or so.

Thanks again for your help, I greatly appreciate it! :)

Originally Posted by Steve House

Just a couple of note ... haven't used either of your pieces of equipment so my previous post was based on general knowledge, in other words, an educated guess.

I completely understand. I totally appreciate the guesses you have provided. :)

Originally Posted by Steve House

"Crackle" is often clipping and it can occur even if levels look normal, depending on where it happens. Take a look at the waveform in your computer - if the peaks are flattened off like a plane has been run across them, that's clipping. Damaged hardware is another possibility but I'd look to clipping first. Which headset do you have, the standard version or the deluxe version with the ME-2 mic capsules?

I purchased the deluxe version (i.e. "Sennheiser"). I figured that the deluxe model would give me the best quality sound possible... That is, if I can get my R-09 settings figured out.

Here is a sample audio file.

And here is a screen grab of a close-up of the waveform in question (the red arrow is where the first click happens in the sample I provided).

I hope that helps fill in some of the blanks.

I will have to experiment with my R-09 settings... Part of me wonders if the battery pack I have is to blame, or is this a clear cut case of "auto" settings ruining an audio capture?

I am hoping it is not a hardware problem. :(

[Steve House]

If you playback the orginal file on your recorder before importing it into your computer do you still hear the 'crackles.' I'm wondering if the harshness you're describing as 'crackles' might have been in the speaker system of the venue where you recorded and you just didn't notice it at the time. Did you record your original in wav or mp3 file format?

[Micky Hulse]

Originally Posted by Steve House

If you playback the orginal file on your recorder before importing it into your computer do you still hear the 'crackles.' I'm wondering if the harshness you're describing as 'crackles' might have been in the speaker system of the venue where you recorded and you just didn't notice it at the time. Did you record your original in wav or mp3 file format?

Ah, good idea!

You know, now that you mention it, and this might be totally stupid to say, but... I do remember noticing that morning that when I swallowed my ears were popping/crackling (normally when I swallow my ears do not pop... Not sure why, but it was very noticeable that morning). Do you think inner-ear pops would be recorded by the mics?

Anyway, I will check the playback off of my R-09 and get back to you (I think I still have the raw/source audio on my memory card).

Also, I recorded the audio in the highest quality possible (wav).

Thanks so much for you help Steve, I really owe you one! ;)

Have a great day!
Cheers,
Micky

[Greg Miller]

Micky, if you're still around, I would be curious to see/hear the original WAV file rather than a file that has been encoded into MP3 format. It doesn't need to be very long, just a few seconds containing the clicks and pops.

Thanks!

[Micky Hulse]

Hi Greg!

I will post a few more samples later tonight.

Thanks!
Micky

[Micky Hulse]

Hehe, so here is what I got. :)

First, here is the clip with the "pops":

clicks.WAV

I was not sure of the best way to save an edit of the original clip other than using QTPro and saving as "source", which saves as .mov extension... I manually changed the extension to .WAV.

Here are some other test clips... Please ignore my dorky voice! :)

#1


Battery pack: Connected
Limiter: off
Low Cut: off
Mic Gain: Low
Plug-in power: Off
Input Level: 50


#2


Battery pack: Connected
Limiter: On
Low Cut: off
Mic Gain: Low
Plug-in power: Off
Input Level: 50


#3


Battery pack: Connected
Limiter: On
Low Cut: On
Mic Gain: Low
Plug-in power: Off
Input Level: 50


#4


Battery pack: Connected
Limiter: On
Low Cut: On
Mic Gain: High
Plug-in power: Off
Input Level: 50


#5


Battery pack: No
Limiter: Off
Low Cut: Off
Mic Gain: Low
Plug-in power: On
Input Level: 50


#6


Battery pack: No
Limiter: On
Low Cut: Off
Mic Gain: Low
Plug-in power: On
Input Level: 50


Surprisingly, I did not get any clicking and/or popping in any of the above 6 tests. Of course, my tests were not scientific and the bass was probably not as deep as the bass was in "clicks.WAV" recording.

Also, I recently upgraded the firmware on my R-09, so I am wondering if that was of some help?

Well, let me know if you would like to hear other samples.

Thanks!
Micky

[Greg Miller]

Hi Micky,

So far I have listened only to the R09_0001.wav which sounds absolutely fine: good levels, no clicks or other extraneous noises.

To try to figure out what went wrong, I really want to listen to the portion of your original file which contains the "clicks." I want to analyze it in a fairly good audio program, something like CoolEdit or Audition. Unfortunately, the file you sent ("clicks.wav") won't open in those programs. I think that's because it's not really a WAV file. If I understand what you did, you saved it in the MOV format, then just renamed the extension. That's not a valid thing to do.

Besides, when a program automatically converts a file like that (from the original WAV file from your R-09, to a MOV file) it could introduce some other problems, as a result of sampling rate conversion, gain change, normalization, etc... maybe some change you didn't intend or even realize was happening.

I really want to look at an *unchanged* portion of the original file. I think the simplest way to do that would be for you to open it in some audio editing program, such as Audition, CoolEdit, Audacity, etc. Then just select (highlight) the portion of the file with the clicks, and use a function with a name like "Save Selection As" to immediately save that portion of the original file, keeping it in WAV format, without any changes to sample rate, gain, EQ, normalization, etc. The key here is to end up with a file in the exact same format as the original problem file, with absolutely no changes! (Of course I could open the entire original file, except it's probably much too big to upload and download conveniently.)

Can you manage to do what I've described above?

Meanwhile, I'll read through the R-09 manual to look for possible trouble spots.

Thanks!

[Micky Hulse]

Hi Greg! Thanks so much for the help, I greatly appreciate the professional advice and assistance. :)

Originally Posted by Greg Miller

So far I have listened only to the R09_0001.wav which sounds absolutely fine: good levels, no clicks or other extraneous noises.

Pheww. I am really happy that I was able to get a decent recording of something with bass... I had my head right next to the speaker and the recording sounded pretty good.

Originally Posted by Greg Miller

To try to figure out what went wrong, I really want to listen to the portion of your original file which contains the "clicks." I want to analyze it in a fairly good audio program, something like CoolEdit or Audition. Unfortunately, the file you sent ("clicks.wav") won't open in those programs. I think that's because it's not really a WAV file. If I understand what you did, you saved it in the MOV format, then just renamed the extension. That's not a valid thing to do.

Doh! Sorry about that!

Using QT is typically what I do for videos when I need to quickly save as the same format. I ignorantly thought this would work for my R-09's wav files. :(

Originally Posted by Greg Miller

Besides, when a program automatically converts a file like that (from the original WAV file from your R-09, to a MOV file) it could introduce some other problems, as a result of sampling rate conversion, gain change, normalization, etc... maybe some change you didn't intend or even realize was happening.

That makes total sense now that you point it out! I will be sure to Audacity from now on. Thanks again for the tips and clarification, I really appreciate it. :)

Originally Posted by Greg Miller

I really want to look at an *unchanged* portion of the original file. I think the simplest way to do that would be for you to open it in some audio editing program, such as Audition, CoolEdit, Audacity, etc. Then just select (highlight) the portion of the file with the clicks, and use a function with a name like "Save Selection As" to immediately save that portion of the original file, keeping it in WAV format, without any changes to sample rate, gain, EQ, normalization, etc. The key here is to end up with a file in the exact same format as the original problem file, with absolutely no changes!

Here is another version. This time I used Audacity and selected the "Export Selection as WAV" from the file menu. I hope this does the trick! Thanks for the tip on how to do it. :)

Originally Posted by Greg Miller

(Of course I could open the entire original file, except it's probably much too big to upload and download conveniently.)

I don't mind posting it if you want to hear the full version. It is a little over a gig, but I have the server space if you think that would be best. :)

Originally Posted by Greg Miller

Meanwhile, I'll read through the R-09 manual to look for possible trouble spots.

Wow! Thanks so much Greg!

I will do the same.

I was kinda wondering if the battery pack was to blame, but my tests yesterday did not yield any negative results when it was being used.

On the other hand, I did upgrade the R-09 firmware recently, and I am wondering if that was the fix I needed.

One last thought... Do you think the mics could pick up inner-ear pops? I know this might sounds silly, but that morning my ears were popping (more than usual) when I swallowed. When I was recording, I remember thinking to myself "I wonder if my ear pops will show up the recording?".

Anyway, thanks so much for your assistance. I owe you one! :)

Have a great day/night.

Cheers,
Micky

[Steve House]

I'm still not ruling out that there might have been clipping or speaker crackles from overloading at high volumes in the PA system that you were recording rather than in the recording you yourself made of it. Perhaps you were recording what actually was there. I've been in many venues and movie theatres, etc, where the PA wasn't up to par and some idiot who thought "louder is better" cranked it up beyond what the system could properly handle. You might not notice it at first hearing on-site but in the leisure of listening again it becomes apparent. In your first recording there's so much bass it sounds like whoever setup the PA thought "good means as much bass as you can get" and cranked the amplifier's bass control all the way to 11. I loaded your clip into Soundforge and looked at the waveform. There are spikes at the crackles but they're not showing the flattened peaks indicating clipping or going so high as to threaten clipping, making me wonder if they might have already been in the original source sounds. Of course the waveform I'm seeing may be an artifact of your file conversion processing

[Greg Miller]

Steve, I certainly agree that we can't rule out anything yet. At first glance those little clicks are interesting, in that they are so brief... only 3 or 4 samples in duration. And nowhere near 100% FS.

But then I notice that the latest file has a 96kHz sampling frequency. And according to the Owner's Manual, the R-09 has a maximum sampling frequency of 48kHz. That means that this is *not* a snippet of the original file, but rather a new file that is apparently a resampled version of the original. That resampling could easily obscure whatever went on in the original file.

So, Micky, I am going to ask you to post the entire original WAV file, just as it came from the recorder. We are just wasting time looking at resampled (and otherwise possibly altered) versions of the audio.

[Steve, do you know of any freeware or utility that Micky could use to actually just snip and send a short portion of the file, guaranteed to be *unaltered*? I don't believe he has Audition.]

Micky, when you post again here, please list some of the actual times where those clicks occur in the original file, so we do not need to listen to the entire thing.

Carry on.....

[Steve House]

Originally Posted by Greg Miller

...

So, Micky, I am going to ask you to post the entire original WAV file, just as it came from the recorder. We are just wasting time looking at resampled (and otherwise possibly altered) versions of the audio.

[Steve, do you know of any freeware or utility that Micky could use to actually just snip and send a short portion of the file, guaranteed to be *unaltered*? I don't believe he has Audition.]

...

How about freeware Audacity? Available for both Windows and Mac. All it'll take Miicky to get it up and running is about 10 minutes of his time for the download and install.