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Author Topic: Absolute Phase???!!!  (Read 3368 times)

Offline stellavox

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Absolute Phase???!!!
« on: March 07, 2007, 04:27:20 PM »
Lat night I was listening to a Benny Goodman master dub sent by a friend and noticed that the wasn't much depth to the image.  As this recording was of a full jazz band recorded in a good hall I assumed there might be something "wrong", so I reversed the polarity of the speaker leads to my Quad 63.s and there was the depth - in spades.

Now I've tried this with CD's before and realized that on my system, absolute phase reversal "shifts" the whole image backwards or forwards but wouldn't effect the relative "depth" of, say an orchestra - so I left the polarity as is ("positive" speaker leads connected to amplifier and speaker "positive")

However the DRAMATIC difference I heard last night got me thinking about (and running to review) other dubs to see if this effect happens on others.  It also got me thinking about the whole absolute phase issue as regards tape decks.  Is/was there any industry standard regarding phase? 

Now I also have to check my various decks to see if there is phase consistency between them - bet I'll find that there is NOT.

Charles

Offline classicrecordings

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Re: Absolute Phase???!!!
« Reply #1 on: April 14, 2007, 11:27:08 AM »
Is/was there any industry standard regarding phase? 

I am assuming here, but my guess would be that there was no standard for polarity in the industry either for manufacturers or recording companies, or else early pre-amps by Marantz, McIntosh, Harmon Kardon, and a host of others would never have installed a phase reverse switch.

I use the switch all the time to check recordings. I have found that some Columbia and Everest classical vinyl releases can benefit from reversing phase on playback. Also, multi-track recordings can have the singer in phase and the musicians reversed.

Some modern pre-amps will tell you if they are phase inverting. My Conrad Johnson PV-5 is non-inverting. And now, some of the new high end pre-amps have phase switching on them once again.

David
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Offline slbender

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Re: Absolute Phase???!!!
« Reply #2 on: September 13, 2007, 06:53:36 AM »

Actually there are TWO topics here, first Absolute Phase of both channels and relative phase of ONE channel.

While Absolute Phase of both channels may be poorly understood, and some or many people can't even tell ( and I think I'm among those ) I'm still waiting to be wow'd hearing a really noticeable change by reversing the phase at both speakers.  Considering that there is a story that on many LP's and CD's the Absolute Phase is changed on odd and even cuts, or randomly, if that is true... I guess there is no set rule for Absolute Phase.

The other point, Stereo Channel Relative Phase - The aforementioned Phase Switch that David refers to as found on Early Preamps, and Integrated Amps... was used to reverse One Channel's Phase while not affecting the other Stereo Channel.  There exist many early Stereo recordings, Reel Tapes and LP's where either one channel is out of phase with the other, or some tracks of a multitrack recording, are out of phase with others.  Been documented, supposedly.

So there is Inverting, or Non-Inverting Absolute Phase, and there is Stereo Channel Relative Phase.

-Steven L. Bender


Is/was there any industry standard regarding phase? 

I am assuming here, but my guess would be that there was no standard for polarity in the industry either for manufacturers or recording companies, or else early pre-amps by Marantz, McIntosh, Harmon Kardon, and a host of others would never have installed a phase reverse switch.

I use the switch all the time to check recordings. I have found that some Columbia and Everest classical vinyl releases can benefit from reversing phase on playback. Also, multi-track recordings can have the singer in phase and the musicians reversed.

Some modern pre-amps will tell you if they are phase inverting. My Conrad Johnson PV-5 is non-inverting. And now, some of the new high end pre-amps have phase switching on them once again.

David

Offline ironbut

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Re: Absolute Phase???!!!
« Reply #3 on: September 18, 2007, 09:03:32 PM »
I was just posting on a thread about absolute phase on a different board regarding the output of a balanced electrostatic headphone amp yesterday. With that one and the posting about the XLR outs of the Otari 5050 series and now this one,.. YIKES! My tiny head is spinning!
But seriously, the audibility of correct phase relationships depends on the speakers involved. With my planers, reversing the phase makes a dramatic difference in imaging and even apparent loudness. To make things even more complicated, the bass panels and the mid-tweeter panels are wire out of phase with each other with the stock x-over.
Regarding the multi track recordings with vocalists, I'm not surprised in the least that the singer could be recorded out of phase with the rest of the channels. I just did a good bit of research on Dolby units and some engineers are using Dolby A units with the low freq. band defeated and just encoding the vocalist without decoding to tweak the sound. Reversing the phase would be an easy tweak  (if they like it).
I think I'll go out of phase if I think about it anymore this week so here's the latest article from Clark Johnsen author of " the Wood Effect" that will tell you more than you want to know about phase relationships.
http://www.positive-feedback.com/Issue1/cjwoodeffect.htm
steve koto
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