Become a Site Supporter and Never see Ads again!

Author Topic: Is there a trick to balancing channel volume?  (Read 2539 times)

0 Members and 1 Guest are viewing this topic.

Offline JonG

  • Trade Count: (7)
  • Taperssection Regular
  • **
  • Posts: 174
  • Gender: Male
Is there a trick to balancing channel volume?
« on: April 20, 2017, 09:40:14 PM »
Excuse my lack of technical terms--I'm no sound engineer.

The more I tape, and the I more I work on editing the shows, the more I notice that there's a significant variation in what I *thought* were balanced channels between shows. Say I'll go between shows and find several that each favour either the left or right channel to varying degrees--at least when compared to each other--despite my thinking the balance was good for each show at the time of editing.

I try to balance the channels according to where the bulk of the waveform is when looking it in Sound Forge, but this is mostly eyeballing and listening for it to sound "right." This isn't a problem with every show, and I *think* it's more of a problem at amplified shows rather than acoustic ones. I especially have trouble when there's a significant differences between the channels from the outset, as in when one channel's peaks are significantly lower than the other's due to dampening from the bodies around me. I'm wondering if there's a better and more accurate way to handle this.  ???

Let me know if this reads confusingly and if samples would help. Cheers guys.  :cheers:
« Last Edit: April 21, 2017, 01:35:04 PM by JonG »

Online Gordon

  • Trade Count: (18)
  • Needs to get out more...
  • *****
  • Posts: 10213
  • Gender: Male
    • my list
Re: Is there a trick to balancing channels?
« Reply #1 on: April 20, 2017, 09:44:53 PM »
in wavelab you can pick individual channels and check the gain of each.  figure out the difference and raise the lower one to match as best you can.
Neumann ak40 > Nick mod lc3 > Naiant PFA or km140 > Sound Devices MixPre-6

https://archive.org/details/fav-gordonlw

Offline JonG

  • Trade Count: (7)
  • Taperssection Regular
  • **
  • Posts: 174
  • Gender: Male
Re: Is there a trick to balancing channels?
« Reply #2 on: April 20, 2017, 10:13:08 PM »
Thanks for the tip. I'm messing around in WaveLab Elements now, should I be looking at the average value int he "Global Analysis" window?

Offline JonG

  • Trade Count: (7)
  • Taperssection Regular
  • **
  • Posts: 174
  • Gender: Male
Re: Is there a trick to balancing channels?
« Reply #3 on: April 21, 2017, 09:59:05 AM »
Here's an example.

According to WaveLab, this sample's right channel's average loudness is just .1dB lower than the left and has peaks roughly .5dB quieter than the left, yet the right channel sounds louder to me.
http://www.mediafire.com/file/700hso2c4d2ub7j/

And this is what I came up with in Sound Forge several days ago, which sounds more balanced, at least in comparison, to me.
http://www.mediafire.com/file/bo8848p16b96ct8/

Are my ears made of tin? Is it because the right channel is "clearer" than the left?

For reference, here's something completely different that both my ears and WaveLab agree is balanced.
http://www.mediafire.com/file/dy6aanfsso374h1/
« Last Edit: April 21, 2017, 10:09:41 AM by JonG »

Offline TheMetalist

  • Trade Count: (0)
  • Taperssection Regular
  • **
  • Posts: 58
Re: Is there a trick to balancing channels?
« Reply #4 on: April 22, 2017, 04:44:09 AM »
I have the balance problem with my AKG CK63 capsules as well. It's really annoying. I guess it's caused by the different freq curves between left and right channel. I have tried to eq each channel on their own to find the right balance but so far I can't say I have succeeded. I would need some advice as well.

By listening to your samples, the last one (dy6aanfsso374h1) sounds way more balanced to me than the other two. Seems like you removed some of the bass mudd in left channel?
It's not about fancy equipment. It's about the thrill, passion and hard work. Liberate the music!

"The music is your passport - Your magic key - To all the madness that awaits you." B.L. '86

Offline JonG

  • Trade Count: (7)
  • Taperssection Regular
  • **
  • Posts: 174
  • Gender: Male
Re: Is there a trick to balancing channel volume?
« Reply #5 on: April 22, 2017, 09:53:50 AM »
Yeah, in comparison to the third sample, neither of the first two sound well-balanced. I actually hadn't thought about trying to EQ each channel separately for things like this, so maybe I'll give that a shot, too.

After going through most of my tapes, I think, for most part, it's related to people around me acting as sound dampers. For the majority of my >:D shows I'm in the balcony and the seats are tiered enough that my the way my mics are mounted puts them above everyone in front of me--like in the third sample above. Fixing these shows has been easier. In the past, I just went by ear, which isn't precise enough. So going through and balancing them in WaveLab as Gordon suggested has proved beneficial.

On the other hand, the biggest offenders that I have problems with, as in the first two samples, are at shows where there were lots of people in front of me that were at or above mic-level--one show was super >:D and the mics were mounted lower than normal, and several others were taped from the floor, and I'm on the shorter side of things. Maybe I'd have to EQ the dampened channel separately in those cases? Bass usually isn't effected, but mids and treble usually are.

Edit-
Here's a sample from way earlier in the night. Barely anyone was in the venue--nevermind on the floor--and I think it sounds better. In comparison to the third sample I posted earlier, it still sounds like it favors the right channel. Again, though, WaveLab says the right channel is the quieter channel.  ???
http://www.mediafire.com/file/dha518xlk29bat1/

I might need to be more certain that my mics are as close to facing the same axis as possible. There are times where the mids and treble seems to come through more clearly in the left channel, probably related to my head swiveling.
« Last Edit: April 22, 2017, 10:04:29 AM by JonG »

Offline bombdiggity

  • Trade Count: (11)
  • Needs to get out more...
  • *****
  • Posts: 2196
Re: Is there a trick to balancing channels?
« Reply #6 on: April 23, 2017, 05:05:33 AM »
Here's an example.

According to WaveLab, this sample's right channel's average loudness is just .1dB lower than the left and has peaks roughly .5dB quieter than the left, yet the right channel sounds louder to me.
http://www.mediafire.com/file/700hso2c4d2ub7j/

And this is what I came up with in Sound Forge several days ago, which sounds more balanced, at least in comparison, to me.
http://www.mediafire.com/file/bo8848p16b96ct8/

Are my ears made of tin? Is it because the right channel is "clearer" than the left?

For reference, here's something completely different that both my ears and WaveLab agree is balanced.
http://www.mediafire.com/file/dy6aanfsso374h1/

I didn't listen to samples but yes the average volume in a statistical analysis is a good indicator of reality.  On a mono signal it would be unlikely anyone can perceive a difference of .1 dB.   

I suspect your problem is phase shift between channels.  Phase shift will make channels roughly equivalent in volume seem quite different.  The channel that is ahead in phase will be what you perceive almost regardless of actual volume. 
Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

Offline kuba e

  • Site Supporter
  • Trade Count: (1)
  • Taperssection Regular
  • *
  • Posts: 81
  • Gender: Male
Re: Is there a trick to balancing channel volume?
« Reply #7 on: April 23, 2017, 06:09:13 AM »
I think the problem may be how you angled the microphone pattern when recording. When the microphone pattern is not pointed to the acoustic center, the recording has shifted stereo. This is related to the channels volume and the phase shift of the channels. Gutbucket has well explained it and how to fix it in post-processing. Read these posts:
https://taperssection.com/index.php?topic=178161.0

I have the balance problem with my AKG CK63 capsules as well. It's really annoying. I guess it's caused by the different freq curves between left and right channel. I have tried to eq each channel on their own to find the right balance but so far I can't say I have succeeded. I would need some advice as well.
You can test the microphones roughly. Generate a sinus sweep from 20 hz to 20 khz in Audacity. Then place the microphones verticaly as close to each other and put them close to the speaker. Play the sine sweep, record it and then compare the two signals. They should have approximately the same response. When you play the recording as a stereo, the sinus sweep should sound exactly in the middle.
« Last Edit: April 23, 2017, 06:51:39 AM by kuba e »

Offline TheMetalist

  • Trade Count: (0)
  • Taperssection Regular
  • **
  • Posts: 58
Re: Is there a trick to balancing channel volume?
« Reply #8 on: April 23, 2017, 05:15:17 PM »
I might need to be more certain that my mics are as close to facing the same axis as possible. There are times where the mids and treble seems to come through more clearly in the left channel, probably related to my head swiveling.
I downloaded the complete Katatonia from Dime. Thank you! To me that version sounds more balanced than your sample. Did you do anything different to it?

You can test the microphones roughly. Generate a sinus sweep from 20 hz to 20 khz in Audacity. Then place the microphones verticaly as close to each other and put them close to the speaker. Play the sine sweep, record it and then compare the two signals. They should have approximately the same response. When you play the recording as a stereo, the sinus sweep should sound exactly in the middle.
I did this. Too my ears it sounds like the sweep is in dead center. Didn't look at the recorded file. Maybe I should.
It's not about fancy equipment. It's about the thrill, passion and hard work. Liberate the music!

"The music is your passport - Your magic key - To all the madness that awaits you." B.L. '86

Offline JonG

  • Trade Count: (7)
  • Taperssection Regular
  • **
  • Posts: 174
  • Gender: Male
Re: Is there a trick to balancing channels?
« Reply #9 on: April 23, 2017, 05:54:46 PM »

I didn't listen to samples but yes the average volume in a statistical analysis is a good indicator of reality.  On a mono signal it would be unlikely anyone can perceive a difference of .1 dB.   

I suspect your problem is phase shift between channels.  Phase shift will make channels roughly equivalent in volume seem quite different.  The channel that is ahead in phase will be what you perceive almost regardless of actual volume.

I think the problem may be how you angled the microphone pattern when recording. When the microphone pattern is not pointed to the acoustic center, the recording has shifted stereo. This is related to the channels volume and the phase shift of the channels. Gutbucket has well explained it and how to fix it in post-processing. Read these posts:
https://taperssection.com/index.php?topic=178161.0

I think you guys are on to something, and thanks for the link kuba! Fooling around with the right channel's phase yields a more pleasing, though still imperfect, result to my ears. I gather that's the rub: it's not about trying to reach perfection, but is about trying to choose the next best fit.

Nearly all of my taping is stealth, and although I tend to keep my head facing forward, precise positioning and angling of the mics is impractical. I'll see if I can do something about my setup to minimize this issue in the future, for sure.

I downloaded the complete Katatonia from Dime. Thank you! To me that version sounds more balanced than your sample. Did you do anything different to it?

The one I shared here is a little different than the one I decided to seed. You can hear why I made this post!  :yack:

Offline bombdiggity

  • Trade Count: (11)
  • Needs to get out more...
  • *****
  • Posts: 2196
Re: Is there a trick to balancing channels?
« Reply #10 on: April 23, 2017, 09:07:40 PM »

I think you guys are on to something, and thanks for the link kuba! Fooling around with the right channel's phase yields a more pleasing, though still imperfect, result to my ears. I gather that's the rub: it's not about trying to reach perfection, but is about trying to choose the next best fit.

Nearly all of my taping is stealth, and although I tend to keep my head facing forward, precise positioning and angling of the mics is impractical. I'll see if I can do something about my setup to minimize this issue in the future, for sure.


You need to be aware of positioning and movement.  I can usually hear incidental movement on head mount recordings. 

I suggest collar/shoulder mount.  That is much easier to keep in consistent orientation and IMO makes more of a difference to the result than the relatively small additional height of head mount.  It also make the recording process less of a burden.
Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

Offline Gutbucket

  • record > listen > revise technique
  • Trade Count: (13)
  • Needs to get out more...
  • *****
  • Posts: 11590
  • Gender: Male
Re: Is there a trick to balancing channel volume?
« Reply #11 on: April 24, 2017, 10:11:21 AM »
All that really matters is how it sounds, not how levels look in the editor.  Best practice is balancing the stereo image by ear while listening, rather than trying to do so by eye looking at levels. 

If in doubt concerning the balance accuracy of your hearing, set the balance using headphones, then flip the headphones around (put the left driver on your right ear and vice-versa) to confirm that the balance remains centered even though the image will be mirror-image reversed.  You can use the same trick using speakers, but it's not as quick and easy.

Also it helps to listen to each channel in isolation as a basic timbre check.  When doing that, any obvious frequency balance problems in one channel should become more apparent.  If problematic enough, and if you aren't adverse to applying EQ, you can EQ the problematic channel to better match the response of the good sounding one.   The key there is to aim for matching the basic timbre of the better sounding channel, rather than going for any general overall EQ corrections.  If the entire recording will benefit from further EQ correction, do that later in a separate step using another EQ application to both channels.  This two step EQ process can often greatly improve the quality of a recording.

Here's my post in the thread Kuba e linked previously that sums it up- https://taperssection.com/index.php?topic=178161.msg2192735#msg2192735

If you end up having to make the same corrections every time, it may indicate response problems with your gear (probably one microphone).
volition > vibrations > voltages > numeric values | numeric values > voltages > vibrations > virtual teleportation time-machine experience

Offline anr

  • Trade Count: (1)
  • Taperssection Member
  • ***
  • Posts: 349

Offline bombdiggity

  • Trade Count: (11)
  • Needs to get out more...
  • *****
  • Posts: 2196
Re: Is there a trick to balancing channel volume?
« Reply #13 on: April 25, 2017, 12:52:59 AM »


^ All of course great ideas.
 
If it is a phase issue, rather than (or combined with) other things, for those who have no familiarity with phase shift or phase cancellation I'd offer a few observations along those lines:

Phase shift is easier to get a handle on with headphones. 

Phase cancellation, which can occur when the channels are out of phase, usually manifests as the lows sounding weak when the two channels combine.  Of course if you're using headphones the channels are discrete (not combined in space) so you don't hear the cancellation you would when the two channels combine in a room through speakers. 

If your recording sounds considerably different and better in headphones than by speakers you likely have phase issues to address (and getting it sounding good on headphones may still yield a disappointing sound on speakers if you didn't correct the phase issues).

HTH
Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

Offline kuba e

  • Site Supporter
  • Trade Count: (1)
  • Taperssection Regular
  • *
  • Posts: 81
  • Gender: Male
Re: Is there a trick to balancing channel volume?
« Reply #14 on: April 25, 2017, 04:54:51 AM »
If in doubt concerning the balance accuracy of your hearing, set the balance using headphones, then flip the headphones around (put the left driver on your right ear and vice-versa) to confirm that the balance remains centered even though the image will be mirror-image reversed.  You can use the same trick using speakers, but it's not as quick and easy.
An interesting test is also to play the sine sweep as a stereo in the headphones. For example me, i do not hear some higher frequencies in the center but more to one side. At the highest frequencies, it again centers.


Phase cancellation, which can occur when the channels are out of phase, usually manifests as the lows sounding weak when the two channels combine.  Of course if you're using headphones the channels are discrete (not combined in space) so you don't hear the cancellation you would when the two channels combine in a room through speakers. 
You can also check visualy if the channels have flipped phase. This procedure does not apply to patterns with negative lobe, eg.  fig 8 or hypers. Find a short, independent clap, which is noticeable on the right and left channels. If the signal rises in the right and left channels, record should be in phase. If the signal in one channel rises and in the second goes down, the recording is out of phase.

I hope I use the correct terminology. Phase shift is a time delay of one channel over the other. It has an effect on the stereo image. Out of phase is flipped phase (flipped polarity) but no delay. It's interesting to play the mono signal in the stereo speakers with flipped phase in one channel.

 

RSS | Mobile
Page created in 0.231 seconds with 37 queries.
© 2002-2017 Taperssection.com
Powered by SMF
Website Design by Foxtrot Media, Inc., a Baltimore Website Company