Absolute Polarity

[Dave Martin]

I had something fairly unique happen yesterday. We were cutting fiddle tracks, and after less than 10 minutes, the fiddle player asked if I were doing anything different that usual; her fiddle didn't sound like it usually does over here. She said it sounded 'too pointy'. I checked - same mic (M582 with an M62 capsule), same preamp (Vintech X73 with no EQ), same compressor (Tube Tech CL-1B), and she was even using the same headphones that she usually uses - Fostex T20's (7506's are uncomfortably bright for a lot of fiddle players). After trying a few things, I noticed that the phase switch on the Vintech had beed reversed from its usual position. I changed it back and she was happy. It was a fairly subtle difference, but it was there.

Since I've always read that human tonal memory is not reliable (read a discussion of ABX testing or or the set up for laboratory controlled double-blind tests), and I've also read that absolute polarity is usually not detectable by ear, how did she know? It had been probably three or four weeks since this musician had worked over here, and she's most likely worked in 15 or 20 other studios in the interim. How many of you listen for changes caused by switching phase on a mono track? How often will you reverse phase on a mono channel to see which way you prefer the sound? I almost never do, partly because I've never thought about it, and partly because only the upper faders on my console have a phase reverse switch. I'd need to flip faders on any given channel, then play around with the switch. It seemed to be a lot of trouble until now, but I'm going to start experimenting with it.

[Bob Olhsson]

Polarity makes a night and day difference to anybody overdubbing through a microphone. One of the coolest "more me" boxes I ever saw had polarity switches for both the track an the mike feed.

[Dave Martin]

Originally posted by Bob Olhsson
Polarity makes a night and day difference to anybody overdubbing through a microphone. One of the coolest "more me" boxes I ever saw had polarity switches for both the track an the mike feed.

My Mor me does, though you have to reach into the back of the unit to do so.

[sonic dogg]

I always use my phase switches on tracking...it seems to isolate and clear up mud when theres multiple micing going on...especially on drums...much easier and quick fix than hunting down with the eq...and 'live on stage' its a godsend...since we are a 'sorta' bluegrass band(oddgrass if you will) and theres all these acoustic instruments going...like banjos and stuff...its the only way at times of getting a mix at all.....PHASERS ON STUN MR SPOCK.....

[Jules]

One day I will pick up a Galaxy Phase Clicker / Checker from Fletcher, some folks swear by them.

http://www.mercenary.com/cricket.html

[cymatics]

I can flip the polarity of the line level inputs on my console (D&R Dayner), so I often check low frequency sources to make sure there is no difference between 0 and 180. More often than not, I can't tell the difference. Check out the following link:

http://www.d-and-d.com/mrivers/poltest.html

If you ever had any doubt that polarity affects frequency response, this should settle it.

I would argue that while there is such a thing as absolute polarity, it is not as important as determining which sounds better. If you stop to think about it, every transducer in a recording signal chain is imperfect, therefore, will respond differently to positive pressure vs negative pressure. While this is a simple matter of fact, the resulting differences being judged as better one way or the other is entirely subjective.

- jon

[studjo]

Don't you think it has something to do with the mix she heard, when she was playing? The headphone doesn't isolate the fiddle 100%. So it could be a phase thing between two sound source.

just a thought, but you probably checked that.

Jo

[e-cue]

Originally posted by Jules
One day I will pick up a Galaxy Phase Clicker / Checker from Fletcher, some folks swear by them.

....These are simply a MUST for any film scoring sessions (which I loathe more than drinking pepsi through my nostrils while chewing tin foil and shaving my head with a cheese grinder after being tied naked to a ceiling fan with dental floss and having a nun rub poison ivy on my ass)

[BrianT]

Originally posted by Bob Olhsson
Polarity makes a night and day difference to anybody overdubbing through a microphone. One of the coolest "more me" boxes I ever saw had polarity switches for both the track an the mike feed.

That makes a great deal of sense, given the inevitable mixture of bone conduction, acoustic return in the room and delayed (however minutely) cue feed back into the cans,

Still, ever so nice of you to point that out, Bob. Funny the things we forget. BTW, I owe you a phone call. Sorry for the delay.

Brian T

P.S. How about that A/C bleed in the C.R.? Wow.

[Dave Martin]

Originally posted by BrianT


That makes a great deal of sense, given the inevitable mixture of bone conduction, acoustic return in the room and delayed (however minutely) cue feed back into the cans,

Yeah, I can accept that OK, but what kind of surprised me is that the fiddle player remembered enough of her typical tone here to comment on it. Especially since I know that I'm the only one of her accounts that uses that mic.

And the AC was nice. Maybe it'll be fixed by the time the room goes on line, but it reminds me that Ted at Accurate Air is THE guy for HVAC in studios. He did my room, I believe some of the rooms at Sound Stage, and the Tracking room.

[Bob Olhsson]

Dave and everybody, just put on a pair of cans and talk into a mike while flipping the phase. It isn't exactly subtile.

I've been a part of building quite a few rooms over the years across a whole range of budgets and designers. I was a bit shocked although I suppose it wasn't as bad as what a popular designer from New York generally does.

[recorderman]

Originally posted by Bob Olhsson
Dave and everybody, just put on a pair of cans and talk into a mike while flipping the phase. It isn't exactly subtile.

I've been a part of building quite a few rooms over the years across a whole range of budgets and designers. I was a bit shocked although I suppose it wasn't as bad as what a popular designer from New York generally does.

Ahh..very true..but you need to know for sure if your cans are correct for this to be valid. case in point: A very famous engineer/producer working in another room from me once used his clicker on the vocal mic through his ns10's without checking the chain (i.e. to see oif the console, mic tie line, etc were in absolute polarity)...he his ns10's to be 180 out. He fliped the leads into them. When thew assistant told me this I (having only just the week before checked EVERY mic, speaker, ect e=in every room in the facillity) scoped it out. Wouldn't you know that the mic cable was a phase reversal (who did that?)...so he recorded the vocal 180 out.

[Bob Olhsson]

The sound of the phones is either right acoustically or it isn't. When it isn't but should be, you've got to fix the studio. We hit a reversed cable like that at a very famous film mixing facility and made them stop the clock and phase pop the entire room. Sure enough, we found a LOT of problems.

[Mats Olsson]

There is a cool new thing from Little Labs that is a true "how-could-I-ever-work-without-this-one?" thingamajig.

http://www.littlelabs.com/ibp.jpg
Little Labs IBP Analog Phase Alignment Tool


/Mats