Phase Inversion: how well can you tell?

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Phase Inversion: how well can you tell?

Postby vintage_dog » Tue Sep 14, 2004 4:27 pm

can folks share what they do to determine phase inversion of their audio gear and if they correct it at all? (not to confuse "phase inversion" with "out-of-phase")

most of the time i can't determine sonically if my amp or preamp is phase inverting by just listening to them...

i understand some recordings (CD and LPs) are phase-inverted. CD players, DACs, preamps, amps, speakers could be phase-inverted. for example CJ preamps are phase inverting, but not sure if folks actually correct their system by inverting the polarity at the speaker terminals (unless the amp in inverting as well).

here's an interesting thread on the topic:

http://db.audioasylum.com/cgi/m.mpl?for ... =&session=
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Postby jonas » Tue Sep 14, 2004 5:28 pm

im inverting at the speaker terminal but im not sure if it has an effect. i was told to do so by the manual and confirmed by the dealer.
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Postby bomalabs » Tue Sep 14, 2004 5:54 pm

hola amigos y amigas. emphasis on the amigas.
one can usually tell if the phase, or to put it simply, the plug at the end of your compnent is properly set, by the sound of your whole set up. take note, however, that this is a tedious process, as you will have to do this process to the entire chain of components in your system. so while you may be correct in the setting of the phase of the preamp, when you hook up the cd player, the sound might not be altogether "there", but a simple remedy such as inverting the plug at the end will make your whole sound come alive. start with your your playback sytem and end with the amplifier, as there is no other way to tell if thie amp is set up right except by doing such. you will be pleasantly surprised at how much money this tweak will save you. actually, you should all pay the vintage dawg for passing you this tip without a service fee. it's nice to be writing on this forum again. i've been confused as to where to write, actually, since i was asked not to make cmon down my home. maybe you guys have some suggestions. i will surely welcome them. love advice also given but not to hein. he has broken too many hearts as it is. thanks from the lost writer. mabuhay ang Pilipino. pero hindi lahat.
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Postby jo2 » Tue Sep 14, 2004 6:59 pm

Try this trick.

Get a familiar MONO VOCAL recording play it on your current system. LISTEN...

Now change or hook-up one at a time another pre, dac, TT, amp, etc... on the current system. LISTEN AGAIN

You will see and hear other equiptments make the singer/vocalist too far , too close or coming to both speakers.

I found that if the singer is smack dead center between speakers, that means your set-up is properly in-phase... in my opinion .

Also some TUBES/VALVES on pre-amp inverts the phasing of the signal.

Hope I made sense but please do try it , nothing to loose here. :wink:
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Postby Andaleon » Tue Sep 14, 2004 7:22 pm

A good pre-amp or DAC (that's for CD playback) should have a convenient phase invert switch. I have them in both my pre-amp and DAC.

I correct for phase invertion via my pre-amp via remote (see Americans are spoiled). I have all my CD's cataloged and I know which ones are inverted and press the right sequence of buttons on the remote.

And viola !- MUSIC. Now, where's my wine?
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Postby rtsyrtsy » Tue Sep 14, 2004 9:50 pm

VD,

I think master Hyperion has discussed this at length before but I'm not sure where (could be AA, could be the old Pinoydiophiles).

From what I remember, it doesn't always work out 100% since the recordings are themselves inverted about half the time.

I do have a phase inverting pre-amp AND a phase-inverting power amp. I've played around a bit with reversing the speaker leads (both speakers, siyenmpre).

The difference is subtle. But when you hit it right, everything just comes together. The sound is tighter, faster, crisper, more focused.

If you are in audiophile mood, it's worth the effort. If you are in music lover mood, I agree with Andaleon...where's the wine? This of course is just my humble opinion and your mileage may vary.
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Postby zach » Wed Sep 15, 2004 12:48 pm

hmmm....this is where mang dimas phase/polarity testr comes in handy. :) great gadget!!!
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Postby amandarae » Wed Sep 15, 2004 1:14 pm

Also, an oscilloscope and a frequency generator can do the trick.
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Postby jadis » Wed Sep 15, 2004 9:03 pm

VD,

I have an EMI LP called 'The Enjoyment of Stereo' in which the 3rd cut, Phasing, has
John Borwick, the Audio Editor of Gramophone; talking in 2 kinds of phase. And when one's
system sounds diffuse while he talks, he advises the owner to reverse the positive and negative leads in the speaker end. Luckily, my system sounds normal while he talks. :)
But, he speaks as if phase inversion is a solution to 'out-of-phase' sound.
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Postby Jon Agner » Thu Sep 16, 2004 2:16 pm

bomalabs wrote:hola amigos y amigas. emphasis on the amigas.
one can usually tell if the phase, or to put it simply, the plug at the end of your compnent is properly set, by the sound of your whole set up. take note, however, that this is a tedious process, as you will have to do this process to the entire chain of components in your system. so while you may be correct in the setting of the phase of the preamp, when you hook up the cd player, the sound might not be altogether "there", but a simple remedy such as inverting the plug at the end will make your whole sound come alive. start with your your playback sytem and end with the amplifier, as there is no other way to tell if thie amp is set up right except by doing such. you will be pleasantly surprised at how much money this tweak will save you. actually, you should all pay the vintage dawg for passing you this tip without a service fee. it's nice to be writing on this forum again. i've been confused as to where to write, actually, since i was asked not to make cmon down my home. maybe you guys have some suggestions. i will surely welcome them. love advice also given but not to hein. he has broken too many hearts as it is. thanks from the lost writer. mabuhay ang Pilipino. pero hindi lahat.


GK,

Should one do this test after properly tuning the room, or can we do this even without tuning the room? Correct me if my understanding is wrong: room reverberation, as I understand it, has an effect on the sound we hear, especially if the direct and reflected signals are cancelling each other out. If we do this without tuning the room, would it be possible that the phase inversion and/or cancellation may be caused by room reverberation and not by the equipment itself (sorry if this may considered an OT but I think its related :) )?

Thanks.

Jon
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Postby JackD201 » Tue Nov 09, 2004 3:47 am

Mmmmm not really Jon, phasing is more a time domain smearing in the "out of phase" way the topic is on the polarity inversion type used by some recording engineers, very few mastering engineers and some manufacturers to enhance or give a larger sense of space by actually producing a sound psychoacoustically similar to the room tone of large venues. What you are referring to is called comb filtering. What our beloved tweaker friends are concerned with occurs within the electrical chain affecting what comes out of the speakers.
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Postby johnmarc0 » Tue Nov 09, 2004 7:15 am

Usually you can not tell if a recording has the phase inverted (or phase delay more than 180 degs) are introduced.

Phase is usually measured with a phase reference signal and phase measured signal. The difference bet the ref and the measured signal in the time domain allows you to qualify the degree of phase difference of the measured signal from the ref.

Thus, unless you have a copy of the "unphased" master recording you could not tell the difference.
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Postby dogears » Tue Nov 09, 2004 10:52 am

I read somewhere that Norah Jones' Come Away with Me album was recorded with an inverted phase.
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Postby Jon Agner » Wed Nov 10, 2004 10:25 am

JackD201 wrote:Mmmmm not really Jon, phasing is more a time domain smearing in the "out of phase" way the topic is on the polarity inversion type used by some recording engineers, very few mastering engineers and some manufacturers to enhance or give a larger sense of space by actually producing a sound psychoacoustically similar to the room tone of large venues. What you are referring to is called comb filtering. What our beloved tweaker friends are concerned with occurs within the electrical chain affecting what comes out of the speakers.


JackD,

Thanks :)
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Postby tony » Sat Nov 26, 2005 12:36 pm

a double pole single throw in series with your speaker cables can be installed if you want to hear this so-called phase inversion while listening.

there can be only two condition any way, either phase was inverted or it was not.

and i doubt you can tell the differnce.
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Postby JackD201 » Sat Nov 26, 2005 3:59 pm

I agree. On a lot of material it is very tough to tell. It's not so much something you hear as it is a sensation. A fuzziness around images that seems to rouch out into your plane and sometimes behind you in the extreme but more of distortions in the shape of the soundscape's horizontal plane. It can also produce something of a weird ringing inside your skull (as if the sound was coming from inside your head). This happens with sustained high frequency notes. Something very rare except in electronic music, that I suppose is why normally it's only those with ultra-finetuned ears that can catch it without trying.

Depending on speaker design it's common also to hear added boominess and dull highs. None of this is readily apparent in the speakers i own. I'd really like to know why. If anyone can explain this I'd be very grateful.
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Postby tony » Sun Nov 27, 2005 7:27 am

only God knows how many times, and at what phasing, the original recording may have been played around with before a final product was sent to market.

the mariage between speakers and amps is tenuous one, the one reason why BOSE is so succesfull despite being maligned in some forums is that they do not sell amps per se, they sell speakers with amps which have been optimised to work together synergistically.

therefore i have this belief that amps whould be designed based on particular speaker, to make is work very good.
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