The No.1 Website for Pro Audio
A-B monitoring (listening with one channel out of phase) HOW?
Old 30th January 2007
  #1
Deleted User
Guest
A-B monitoring (listening with one channel out of phase) HOW?

A-B monitoring (listening with one channel, L or R, out of phase to cancel the phantom center) can reveal some cool elements of a mix when critically listening to other engineer's work. I've been told the obvious solution to do so is reversing the the polarity of the speaker cable of one of the monitors. This is an easy task for passive monitors, but I have a completely balanced system with active monitors (002 -> big knob - > krk v8's). Is there any simple way to listen to songs "A-B" without buying a spare balanced cable and messing with it? I usually listen to music in iTunes which connects to the 002 with the Digi CoreAudio Manager. Is there a software solution that can accomplish what I'm trying to do?
Old 30th January 2007
  #2
Here for the gear
 

VST Plugin ToolsOne ???
Old 30th January 2007
  #3
Lives for gear
 
soundeq's Avatar
 

Here's the pro tools approach..

take your stereo file you want to "A-B"
split it on to 2 mono tracks... (IMPORTANT!) pan them both DEAD CENTER! (A-B is a mono thing)

Find some kinda plugin that has a phase flip on it.... put it on BOTH tracks (so plugin delay won't be an issue)
Bypass one plugin, and activate the polarity reverse on the other track)

Voila, "A-B"

another approach would be split the tracks to 2 mono tracks, and use Audio Suite polarity reversal (on only one track, doesn't matter what one) I think its called "invert" or somthing like that.

Have fun!
Old 30th January 2007
  #4
Lives for gear
 
soundeq's Avatar
 

ohh and the "non active" monitor way to listen to "A-B" is to use ONE speaker, and plug the RED and BLACK on the back of the speaker to LEFT RED, and RIGHT RED on the back of the power amp.
Old 30th January 2007
  #5
Lives for gear
 
soundeq's Avatar
 

lemme guess, Boston MA, you go to Berklee, and just leared about A-B today huh? it's nifty, although not that usefull, unless you want a cool way to sample records
Old 30th January 2007
  #6
Lives for gear
 
Bob Ross's Avatar
 

Quote:
Originally Posted by soundeq View Post
lemme guess, Boston MA, you go to Berklee, and just leared about A-B today huh?

Ouch...
Old 30th January 2007
  #7
Deleted User
Guest
Quote:
Originally Posted by soundeq View Post
lemme guess, Boston MA, you go to Berklee, and just leared about A-B today huh? it's nifty, although not that usefull, unless you want a cool way to sample records


i should also mention that i was looking for a non protools solution. its simple enough to import a song into a session and do it there, or even in a program like peak. i was just wondering if there was a quicker "on the fly" way to do it short of flipping the speaker leads for the passive monitors i dont have haha.
Old 30th January 2007
  #8
Gear Addict
 

Get a Crane Song Avocet. You can A-B your demos all day. It also has a nifty little "Phase" button that you can press and it will flip phase of one speaker.

Regards,
Bruce
Old 30th January 2007
  #9
Lives for gear
 
soundeq's Avatar
 

Quote:
Originally Posted by Bob Ross View Post
Ouch...
Nah I didn't mean it in a bad way, I remember that day myself! I musta listened to nearly 100 records in A-B that week.

as for a simple itunes plugin, I doubt your gonna find it, the general public isn't interested much in A-B.

you could make your own XLR Y cable, if you have soldering skills. 2 connectors on the female end (L and R out of your 002), one on the male end (to one speaker)...
Connect pin2 from one side of the female, pin3 from the other side of the female, and connect them both to pin 2 on the male side. same thing with pin3 on the male, use the remaining pin2 and 3 female. Pin 1 is ground, nothing to cross there.

sorry I can't make it any easier for ya!
Old 30th January 2007
  #10
Deleted User
Guest
Quote:
Originally Posted by crna59 View Post
Get a Crane Song Avocet. You can A-B your demos all day. It also has a nifty little "Phase" button that you can press and it will flip phase of one speaker.

Regards,
Bruce
The Avocet looks great, but is way out of my budget (my Big Knob does everything else I need...minus phase flipping)

Quote:
Originally Posted by soundeq View Post
Nah I didn't mean it in a bad way, I remember that day myself! I musta listened to nearly 100 records in A-B that week.

as for a simple itunes plugin, I doubt your gonna find it, the general public isn't interested much in A-B.

you could make your own XLR Y cable, if you have soldering skills. 2 connectors on the female end (L and R out of your 002), one on the male end (to one speaker)...
Connect pin2 from one side of the female, pin3 from the other side of the female, and connect them both to pin 2 on the male side. same thing with pin3 on the male, use the remaining pin2 and 3 female. Pin 1 is ground, nothing to cross there.

sorry I can't make it any easier for ya!

i think the modified cable route is the direction i'll go eventually. for now i'll stop being lazy and just import the song into pro tools or peak.
Old 30th January 2007
  #11
Lives for gear
 
el cochino's Avatar
 

Quote:
Originally Posted by nerogtr View Post


i should also mention that i was looking for a non protools solution. its simple enough to import a song into a session and do it there, or even in a program like peak. i was just wondering if there was a quicker "on the fly" way to do it short of flipping the speaker leads for the passive monitors i dont have haha.
I think Phasetone can do this and it's free.
Old 30th January 2007
  #12
Deleted User
Guest
Quote:
Originally Posted by el cochino View Post
I think Phasetone can do this and it's free.
phasetone is still a plugin, which doesn't free me from opening up pro tools. however, i think i'm going to download it anyway- its free haha. no $$ is always a good thing.
Old 30th January 2007
  #13
Lives for gear
 
max cooper's Avatar
 

Do you have active monitors?

Just make a polarity reversed cable (if it's XLR, flip pins 2 and 3, usually)

If the speakers don't have grilles on them, you can pull the drivers and flip the leads internally.

If you're using headphones, you can make a cable that's female to male; flip the tip or the ring.

If you're using a turntable, you can wire one half of the cartridge leads in reverse.
Old 30th January 2007
  #14
Deleted User
Guest
Quote:
Originally Posted by max cooper View Post
Do you have active monitors?

Just make a polarity reversed cable (if it's XLR, flip pins 2 and 3, usually)
reverse.
i think thats going to be the way to go. my ear says stay consistent and use a monster studiolink cable (what i'm currently using)....but my wallet says find something cheaper to ruin and screw with.
Old 31st January 2007
  #15
Lives for gear
 
soundeq's Avatar
 

I think your missing how you actually go about doing this.

A-B isn't just flip pins 2 and 3... you have to COMBINE the LEFT and RIGHT sides togeather into a MONO signal, puting ONLY ONE side out of phase.....

Simply switching the phase on your left speaker and leaving your right one alone, and playing a stereo song through it WONT work for a TRUE "A-B"! (it'll just sound F*$*ED up in the center, and hurt your head, but you won't get a true cancelation)

Hope this helps clarify things...
Old 31st January 2007
  #16
Deleted User
Guest
Quote:
Originally Posted by soundeq View Post
I think your missing how you actually go about doing this.

A-B isn't just flip pins 2 and 3... you have to COMBINE the LEFT and RIGHT sides togeather into a MONO signal, puting ONLY ONE side out of phase.....

Simply switching the phase on your left speaker and leaving your right one alone, and playing a stereo song through it WONT work for a TRUE "A-B"! (it'll just sound F*$*ED up in the center, and hurt your head, but you won't get a true cancelation)

Hope this helps clarify things...

no no, i got it. i just didn't mention mono in my original post because listening in mono isn't what im having trouble with. i've got a nice big mono button on my big knob. probly should have mentioned the mono while "explaining" a-b though. my bad. so, are you a berklee alum?
Old 31st January 2007
  #17
Lives for gear
 
soundeq's Avatar
 

yep (sheepishly) I am an alum... Kinda like wearing a big Scarlet "A" in here.
Old 31st January 2007
  #18
Deleted User
Guest
Quote:
Originally Posted by soundeq View Post
yep (sheepishly) I am an alum... Kinda like wearing a big Scarlet "A" in here.
haha, whatever. its not anything i brag about, but its def not something im ashamed of. most of the best out there didn't go to school for what they do, but its not making me worse at what i do.
Old 31st January 2007
  #19
Gear Guru
 
u b k's Avatar
 

audio hijack pro is something like $30 and will do this.

it's a great little app that intercepts *any* app's sound output and lets you insert any au plugs you have. each app has its own fx rack. i use it all the time to stick a compressor on the dvd player, so that i can listen at low volumes and still hear the quiet dialog.

but there's a built-in au called 'karaoke' that does a minus b.

for the record, doing a minus b in the analog realm via something like the avocet works better than a plug.


gregoire
del
ubk
.
Old 31st January 2007
  #20
Deleted User
Guest
Quote:
Originally Posted by u b k View Post
audio hijack pro is something like $30 and will do this.

it's a great little app that intercepts *any* app's sound output and lets you insert any au plugs you have. each app has its own fx rack. i use it all the time to stick a compressor on the dvd player, so that i can listen at low volumes and still hear the quiet dialog.

but there's a built-in au called 'karaoke' that does a minus b.

for the record, doing a minus b in the analog realm via something like the avocet works better than a plug.


gregoire
del
ubk
.
i'm going to download and try the demo of audio hijack tomorrow. being able to use VST and AU plugins on any audio source on the computer is very very cool. as long as it works nicely with the digi coreaudio manger, i think that may be my ticket. i'll post my results once i try it. for now i need some sleep.
Old 31st January 2007
  #21
Deleted User
Guest
ok so i tried out audio hijack pro (cant sleep), and this is going to be the way to go for me. i can open it up, click "hijack itunes" and i can use any VST or AU plugin on the audio coming from itunes. its brilliant, and works seamlessly with the digi coreaudio driver. simply load any plugin that allows you to flip the phase on just one channel. i loaded the waves s1 imager, but there are scores of other plugins that will do the same thing (the Q1 eq will let you do this, in fact, i think most if not all of the waves plugins will). finally, sum to mono (i did this on my big knob).

fyi- i did a a/b test with the s1 with one channel flipped and summed to mono VS the "kareoke" plugin that comes with audio hijack (which was previously suggested). the kareoke plugin is doing something in addition to the phase flip and mono- possibly some EQ. there is an audible difference. the center information is canceled as would be expected, but theres definitely something else going on there too. my recommendation would be to avoid this plugin, and go with a simple plugin that does only what you need it to do (the phase flip of one channel).

update: i just found a plugin that comes WITH audio hijack called "channel tweak" (under the "4FX Effect" category). it has the following options:
-none (unaltered signal)
-swap channels
-monomize (sum to mono)
-duplicate left
-duplicate right
-kill left
-kill right
-invert phase left
-invert phase right


so right off the bat, with no other additional vst or au plugins needed this program has everything you need to listen A-B. simply load up two instances of this "channel tweak" plugin, set one to "invert phase" and the other to "monomize" and you're set. it sounds the same as my initial "waves + big knob" solution. perfect.



u b k: thanks for the sick suggestion.
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump