Olbee Question: HOw does one detect phasing problems?

evon · Post by **evon** » Tue May 13, 2008 9:58 pm

How can you tell, while mixing, for instance that your sound has a phasing problem? Also, how or what plugin/tool is used to rectify this?

three · Post by **three** » Tue May 13, 2008 10:38 pm

i was talking about this to a sound-engineer buddy of mine just the other day, and the general consensus was that it's voodoo. (this is why such things as 2500€ EQ's exist: phase integrity)

if anybody has some practical thoughts, I'd love to hear them as well.

Tone Deft · Post by **Tone Deft** » Tue May 13, 2008 10:41 pm

well, you get cancellation or addition of sound waves in unnatural ways. usually the bass output is too low. phase cancellation of the highs happens when you move your head around, lows are much more noticeable.

if you have to ask, it doesn't matter.

morerecords · Post by **morerecords** » Tue May 13, 2008 10:45 pm

A general rule of thumb:

always convert your master channel to mono using utility tool at different stages of your mixdown and listen to see if everything sounds ok

e.maynard · Post by **e.maynard** » Tue May 13, 2008 10:47 pm

Grab one track of a live mic'ed kit and nudge it left or right. Hear the hi-hats or kick start sounding thinner or washed out? That's the sound of mis-aligned phase.

three · Post by **three** » Tue May 13, 2008 11:04 pm

sure, it can certainly be caught and corrected, but do any of have any good thoughts on how to avoid getting out of phase in the first place?

we were talking to other day about the fact that it certainly does happen even running a system in full-on live mode with nothing but synthesizers generating the music. easy target is compressors which have to impose a certain amount of delay just to do their job, so avoiding latency-full plugins is certainly a decent start, but any of you have any thought on general acoustic hygiene to avoid getting out of phase?

(this is not a challenge, but a hope!)

cheers,

chris

3dot... · Post by **3dot...** » Tue May 13, 2008 11:37 pm

You hear that shit in you're head man...

Nod · Post by **Nod** » Wed May 14, 2008 12:03 am

three wrote:any of you have any thought on general acoustic hygiene to avoid getting out of phase? (this is not a challenge, but a hope!)

Depends whether you're dealing with strictly ITB stuff rather than genuine acoustic issues that microphones, particularly stereo X/Y, ORTF arrangements or mic+DI etc, bring about. Dealing with the former the best suggestion would be to a) train your ears to pick up on what 'out of phase' actually sounds like and b) get a 'goniometer' or track 'correlation' meter like these:

http://www.kvraudio.com/get/2370.html
http://www.kvraudio.com/get/637.html
http://www.kvraudio.com/get/3117.html
http://www.kvraudio.com/get/2061.html

As for the notion that it's 'voodoo' - not at all. In the right hands you can do all kinds of useful stuff ie Ye Olde Phase Trick: http://www.soundonsound.com/sos/oct00/a ... reomix.htm

'take some of the right-hand signal and feed it to the left channel out of phase, while at the same time taking some of the left-hand signal and feeding it to the right channel out of phase. If too much of the out-of-phase signal is added you'll get a 'hole' in the centre of the mix, or you might even enf up with the stereo image swapping sides, but this trick can be quite handy when used with care. Many of you may recognise this effect from using the SPL Vitalizer -- its stereo width control does much the same thing. Rather than use this technique on the whole mix, try just using it on sounds that you want to push out to the sides of the mix, after first mixing them to a stereo subgroup'

3dot... · Post by **3dot...** » Wed May 14, 2008 12:04 am

Love phasing... I do it all the time

three · Post by **three** » Wed May 14, 2008 1:07 am

Nod wrote:[words...As for the notion that it's 'voodoo' - not at all. In the right hands you can do all kinds of useful stuff ie Ye Olde Phase Trick: http://www.soundonsound.com/sos/oct00/a ... reomix.htm...

thanks, those are good links, already in the middle of reading them.

regarding the voodoo, i meant the not-having-things-get-out-of-phase-in-the-first-place pipedream.

the nice thing is that it's fixable on a micro level, i.e., for each track individually by an individual engineer.

a bit of background about why i care:

music in general is moving more and more towards modelling - particularly with some of the research coming out of the states lately - and hey, why not. if the music we make is electronic anyway, and we have the same arsenal of tools, it's much less data to transfer to send you a description of how to generate the sound (including all my picky 11th hour microediting) than actually transporting those specific sound waves to your speakers ... what we're doing now is packing up the actual sound that came out of my speakers, putting it in a digital lunchbox, and then unpacking it on your end.

that way you can listen in the highest quality that the available hardware can provide, not the highest quality that i managed to physically transport to that location.

we as a society (i.e., those who ideally are or should be buying our music, or at least the fruits of the labors at which we toil while we could be making music) have come to accept poor mp3 quality, and sure, it really doesn't make a difference on ipod headphones (will i get sued if i don't call them earbuds?) - and with the advent of surround-mp3 courtesy of fraunhofer it looks to stay that way for a while.

however, mp3 was born at a time where it was the only practical way to move music around. as the opportunity cost of having better quality audio becomes gets lower and lower (even today we could do everything lossless and it would just mean that rather than having 37000 tracks on your ipod you only get to have 15000) i think it's reasonable to expect there to be a fair uptake at some point - at the very latest when the iPhone version 6 offers full 7.1 gonzosurround via μLaserBeamieThingie (steve jobs will be announcing the new faster than instant transfer technology in his next keynote, it can actually transfer the music before you've even played it) a lot of the modeling tech that's in the incubator right now will become quite interesting.

so long story short, it's my theory that one of the challenges at that juncture will be keeping things in phase without anyone who on location to hear it, recognize it, and fix it in real-time while the sound meta-data is being re-interpreted back into the audible spectrum.

so having the technology to fix that problem before it comes up might be the ticket to being able to focus on music and drop the mundane stuff.

anyway, long story, sorry, if you got all the way through that it did wonders for your karma.

cheers,

chris

ps: wow, i feel like a creepy internet crackpot rereading that. just so you know, i'm not. this is not the internet.

kaffein · Post by **kaffein** » Wed May 14, 2008 1:33 am

You will eventually learn to hear what phasing (the bad kind) sounds like...

One way you can tell if any phasing is occurring is to mix any two sounds together - if the volume gets lower on the master channel it is phasing, if it gets louder it is in phase.

An easy way to hear what phasing sounds like is to invert the phase of a mono sample... The volume won't decrease though in this case, but it gives you an extreme example of what to listen for when you CAN hear it. http://www.shuutobi.com/downloads/kick_ ... xample.zip

Another way is to use a phasescope to determine if something is phasing, this will also help train your ear for what to listen for. Anything showing negative on the meter is phasing in this particular type of phasescope.
Gonio 3 is a decent free phasescope http://www.uk-music.de/gonio.html, and it also has unique unintended feature, the dots indicators will brickwall when any effect in your chain has overloaded another one. (unrelated but helpful at times) Use this to check the whole mix and individual instruments.

evon · Post by **evon** » Wed May 14, 2008 3:00 pm

Tone Deft wrote: if you have to ask, it doesn't matter.

Ironically, that was precisely why I asked, because I have never in my digital experience been able to detect one. I have tried examining/matching the sound waves on both the left and right channels of a stereo sound and every thing looked (and sounded) pretty normal to me.

evon · Post by **evon** » Wed May 14, 2008 3:06 pm

morerecords wrote:A general rule of thumb:

always convert your master channel to mono using utility tool at different stages of your mixdown and listen to see if everything sounds ok

That thought had crossed my mind, although I never felt it was worth the time (as simple as it is to do) because I had no reason to considered this a serious problem, especially in the digital domain. However, in my quest to find the "magic" in my mixes/masters I try to bring every known factor to the front for experiment from time to time.

mohler · Post by **mohler** » Wed May 14, 2008 3:09 pm

I can't help but think to myself that this would be a perfect opportunity for EvilEvilEvilEvilEvilEvil (or Evil x X which ever one he is today) to chime in with a witty response about parallel lemurs running multiple instances of phasers on buss channels and it all making better tarnce so not to go worrying your pretty little head about it.

In his absence, you'll have to make do with your own ever so slightly less amusing imagination to fill in the blanks.

(sorry to distract a serious threat that maybe even going some way to answering the question but it's one of those afternoons)

evon · Post by **evon** » Wed May 14, 2008 4:14 pm

I have heard lots of informative replies and am glad I raised the issue. Unfortunately, I do not know what to do if I find my channels are out of phase. I have quite a few plugs that can tell me about phasing problems but thats all. How do I get back on track?