Phase polarity

When I switch my CD to -phase, should there be an audible difference, someone once told me that negative phase can make the sound sound a little more bassier, any truth in that? Or am I just changing the phase polarity.

 

CD players with phase buttons just invert the phase so really there is no audible difference. Some claim there is though...

 

[Note, "Polarity" is not "Group Delay"]

"Observations on the Audibility of Acoustic Polarity"
Greiner, R. A.; Melton, Douglas E.
JAES Volume 42 Number 4 pp. 245·253; March 1994

Abstract: A number of experiments are described which show that absolute acoustic polarity is clearly audible in certain select cases of reproduced sound from acoustical instruments.

 

Interesting. Have you read the paper? What were the conditions that it was audible under?

I was always taught that phase inversion was not audible, but I guess it is more accurately 'not normally audible'. Obviously though, if there are two signals out of phase then it is! Might happen in a studio or a live event for example where there are more than one set monitoring devices.

 

having recently at home dem a preamp with a polarity switch, i can confirm that i am unable to hear ANY difference between + and - phases in a sistem consisting of ATC 20A, VdH The Second cables throught, DIY valve pre based on 4x6SN7 and Pioneer DVD 370 modded.

i was really paranoid about a phase issue as my regular preamp (cary slp98) is phase inverting and i thought i am losing something with it.

although i could be already deaf, after playing for 15 years in clubs all over the place at crazy levels....

 

I am pretty sure I prefer the sound in - phase, but would some tracks have been recorded in negative and some positive?

 

exactly and how can you know what is a correct phase?

unless you mixed this with a case of speakers out of polarity, it creates a totally different result, lack of bass and fake surround feeling

 

coops,
Infact CD's are recorded mostly out of phase.Was told by recording engineer that most are in phase for even numbered tracks and out of phase for odd numbered tracks.It occurs in the manf. process.If your system is resolving enough you can hear a differnce.After numerous listening sessions with several different systems and sources our club members concluded there is a differnce.We noticed that the bass was tighter and better defined.Sibilance was less natural out of phase,and more prominent.The soundstage was more open in phase,the decay and projection of instruments such as horns bloomed into the room,instead of sounding compressed.
Sound when out of phase can be misleading as it tends to soften and relax the program material[a rounding effect].This can be desirable in some systems if thier bright
A simple test is to play a cut for 30 seconds on repeat[One with stand up bass,vocal and piano]and listen to the bass lines,does it sound to big?diffuse?bloated?Are vocals smooth with sibilance less pronounced and natural?If that isn't enough to convert you,if you have a sub with a invert switch reverse it and listen.If out of phase it will be boomy and lose volume.Same will hold true for the main speakers.You will have more volume in phase.
I believe SteroPhile and HiFi+ if my memory serves me correctly,addressed this issue and concluded there is a differnce to be heard.SteroPhile article listed labels that were recorded in absolute correct polarity.Happy listening.
rollo

 

Thanks Rollo, something else I can drive myself mad with during the long winter months ahead!

 

Subwoofer phase is a different kettle of fish, as if your sub is out of phase with your speakers you'll get very obvious cancellations. The phase switch (or dial) on subs is there so that when you can't line your sub up exactly with your speakers, you can attempt to compensate for the phase difference.

Dunc

 

Bravo! This is, without doubt, the funniest thing I've read here this year.

 

Must have been April 1st when the recording engineer told him that.

 

Yes, I find that a bit hard to swallow. Sure, you may get the odd old recording which was mastered incorrectly, but I can't honestly see how this would happen in the manufacturing process,unless it's been requested by Producer !

 

i've wondered what the phase switch on my dac does. now i'll play with it and report back.

 

Many test disc carry an in phase out of phase demo tracks....
ie the chesky disc

Play back to back its clearly audible the difference between the tracks. For my system using this disc the out of phase sound disembodied and without focus or central sharp image. In focus is how I'd normally hear things.

But if you system is out of phase to start with ......

 

I can hear a difference wih my Cyrex but it is very small and subtle. I prefer it phase normal under test conditions, but I'm not sure that I'd notice if sombody sneakily changed it between tracks!

 

Zanash, "out of phase" means the two channels are out of phase with each other - one speaker is pushing while the other is pulling - which leads to very obvious "out of focus" (even behind-the-head) effects. You can do this yourself by wiring one of your speakers out of phase - i.e. connect your amp's "+" terminal to your speaker's "-" terminal - and playing a normal recording.

The phase switch referred to is absolute phase, which basically just defines whether a given signal pushes the driver out or pulls it in. Equivalent to wiring both your speakers out of phase - i.e. connecting "+" on the amp to "-" on the speaker for both speakers. The effect is much more subtle (if audible at all).

Just using common sense I expect inverting absolute phase would be audible to some extent on some instruments and certain kinds of sounds. But no idea if that's actually the case...

Dunc

 

i have the phase permanently inverted on my dac - don;t know why just think it sounds slightly better that way but to be honest it's more likely cos i get a cool little 'I' on the display. whatever the difference is minimal. (to my ears on my system in my world.)

 

yes.....

the cd reproduces an absolute phase change ....

if I've got one speaker out of phase with the other I don't get any stereo imaging. It produces a strange missmash thats oddly like mono but not centrally fixed and the spatial position of instrament is altered. Again this is very obvious.

When I designed and built my own speakers I had a real problem getting he right phase for the tweater and bass on each speaker .. that was very difficult to do by ear, as there were at least six combinations and a rebuild between each!


"Just using common sense I expect inverting absolute phase would be audible to some extent on some instruments and certain kinds of sounds."

If you've not heard the effect.. .don't try to describe it !

get yourself a suitable test disc and take the time to listen, in my system the sound effects are curious, and apparent...its not something you'd miss.

 

Sorry Zanash, didn't mean to cast aspersions on your expertise - it did seem unlikely to me that you didn't know what absolute phase inversion meant!

In my limited experience, absolute phase inversion doesn't have an obvious effect at all, hence my assumption that you were confusing it with channels being out of phase. I'll have to play with my DAC's phase inversion setting and see if I can hear anything more than I have previously...

Dunc