Acoustic Polarity

[Guest]

This thread is prompted by Myles' post on Records for checking VTA/SRA and its link to the Audio Asylum thread on VTA, wherein the latter he remarks on the importance of absolute polarity and how this can vary by record. I was going to post on this topic there but thought better of cluttering it up.

The Atma-Sphere MP-1 was the first preamp I owned that had an easily accessed switch to swap between normal or '0' and inverted or '180 degree' absolute phase. I quickly learned my ears are sensitive to the phenomenon. Happily the ARC line-stages that followed in my room have the functionality available via their remotes. My "discovery" wrt absolute phase was triggered by the ease of switching it, but my awareness really came with higher resolving phono stages. And perhaps as a result of dialing in SRA as well - which I found easier to do with a higher resolving phono stage - or not. Perhaps that was coincidence - it would seem that resolution has no correlation.

==> I'd like to hear from my fellow Nirvanistas what is your view on the phenomenon, its perception and relative importance to your listening. Can you hear the difference? What do you hear?

Is there a dependency on having all drivers in speakers wired in the same phase? I'm vaguely recalling this is not a priority for Wilson.

Calling it a phenomenon gives away my own current view, which largely falls in line with Clark Johnson's, as laid out in his paper/commentary on The Wood Effect:
Yes, Polarity is Absolute - But Only Your Ears Know For Sure! published in Positive Feedback circa 2002.

Another article by Gordon Holt in Stereophile from 1980: Absolute Phase: Fact of Fallacy?

If you've read this far here's a biscuit: Kevin Tellekamp of SRA created a handy Absolute Phase Chart (pdf) that divides record labels into Zero and Inverted. I have tested this guide over the years with my own ears and to a large part find it agreeable. The chart doesn't cover all record labels. While there are exceptions I find it easier to start by adjusting by label.



PS - if this post should go in a different section than Preamps, please move it.

[JackD201]

Oh this is a tough one. Out of phase sounds well...phasey. In my experience almost all recordings are somewhere in between and this is due to mic'ing and or patching and is typically seen at the mix. Lissajous scopes help the mixer here. In phase shows a vertical line and out of phase horizontal. There are implications for mono compatibility so that I think shaped practice then and still applies today for AM and terrestrial analog TV broadcast. I don't really know how SRA/VTA affects this as usually the issue is with Azimuth. Perfectly in phase signals (L and R) should have a +6dBv effect and one theoretically should be able to get in the azimuth ballpark without a Lissajous/vectorscope by converting dBv to dB then shooting for the +6 equivalent with an SPL meter.

Personally I'm not driven batty by this. Maybe I'm just not that sensitive to it.

[Rob]

If you've read this far here's a biscuit: Kevin Tellekamp of SRA created a handy Absolute Phase Chart (pdf) that divides record labels into Zero and Inverted. I have tested this guide over the years with my own ears and to a large part find it agreeable. The chart doesn't cover all record labels. While there are exceptions I find it easier to start by adjusting by label.

but this tells only part of the story, multi track recordings can have one or more tracks out of phase that go uncorrected (unintentionally) when they're mixed down to 2 track.

with all the fussing 'philes go through tweaking their audio many don't know or seem to care about the polarity of their systems. I don't understand why most pre amp mfrs can't provide an absolute phase switch. ARC did for the longest time, I don't know if they still do. I had a Herron Audio linestage that could invert phase through the remote.

[MylesBAstor]

This thread is prompted by Myles' post on Records for checking VTA/SRA and its link to the Audio Asylum thread on VTA, wherein the latter he remarks on the importance of absolute polarity and how this can vary by record. I was going to post on this topic there but thought better of cluttering it up.

The Atma-Sphere MP-1 was the first preamp I owned that had an easily accessed switch to swap between normal or '0' and inverted or '180 degree' absolute phase. I quickly learned my ears are sensitive to the phenomenon. Happily the ARC line-stages that followed in my room have the functionality available via their remotes. My "discovery" wrt absolute phase was triggered by the ease of switching it, but my awareness really came with higher resolving phono stages. And perhaps as a result of dialing in SRA as well - which I found easier to do with a higher resolving phono stage - or not. Perhaps that was coincidence - it would seem that resolution has no correlation.

==> I'd like to hear from my fellow Nirvanistas what is your view on the phenomenon, its perception and relative importance to your listening. Can you hear the difference? What do you hear?

Is there a dependency on having all drivers in speakers wired in the same phase? I'm vaguely recalling this is not a priority for Wilson.

Calling it a phenomenon gives away my own current view, which largely falls in line with Clark Johnson's, as laid out in his paper/commentary on The Wood Effect:
Yes, Polarity is Absolute - But Only Your Ears Know For Sure! published in Positive Feedback circa 2002.

Another article by Gordon Holt in Stereophile from 1980: Absolute Phase: Fact of Fallacy?

If you've read this far here's a biscuit: Kevin Tellekamp of SRA created a handy Absolute Phase Chart (pdf) that divides record labels into Zero and Inverted. I have tested this guide over the years with my own ears and to a large part find it agreeable. The chart doesn't cover all record labels. While there are exceptions I find it easier to start by adjusting by label.



PS - if this post should go in a different section than Preamps, please move it.

Kevin's absolute phase chart comes from the late Lars Fredell piece that was originally appeared in Ultimate Audio around 1998-99 IIRC. Remember this. All the absolute phase determinations were done with CDs back then. Obviously some were new recordings while others were reissues and thus the results might be dependent upon the quality of the remastering. And back then there certainly was the type of attention paid to remastering that there is nowadays. So are the findings pertinent to the original recordings? Probably in some but not all cases. I've seen some people take issue with Lars' findings but that might be one explanation. I'll have to look for the issue but I also recall publishing a letter to the editor from Clark when I ran Lars's piece. If I can find it, I'll take a picture and post it.

Personally, I don't get all bent out of shape over it. I find it to be a small difference. Probably the biggest thing I hear is a slight tonal difference in the upper mids. Actually cleaning your albums makes more of a difference here and bigger improvement in my system. I have to listen for the changes with absolute phase; the differences are immediately apparent with cleaning an lp! Maybe part of my indifference toward absolute phase was it wasn't until the Doshi phono that I had a preamp or phono section where I could easily correct for absolute phase. Absolute phase can actually be changed remotely with the Doshi phonostage. No fuss, no muss.

Many recording/mastering engineers do check for absolute phase though gets trickier and trickier the more mikes being used. I remember Chesky always checking for absolute phase when cutting the RCA Living Stereo releases using exactly the method Jack described. People like Kevin Gray do it routinely. I assume Steve Hoffman does too.

I remember years ago some people pointing out the absolute phase on Sheffield recordings being all over the place.

Perhaps with changes to the system, should go back and check.

[david k]

I'm aware of it more with digital than analog. There was a time when I used to mark the polarity of every track but I don't care anymore, maybe because I rarely ever sit in a fixed sweet spot nor do I analyze the sound and system any longer when listening to music. It's my approach to system building and setup, nothing distractive specially if it's impressive!

david

[Steve Lefkowicz]

Not sure if this is the same issue or not, but years ago when Brian Cheney came to my house to set up my VMPS RM-2neo speakers, the second most time consuming part of the installation (after mass loading the passive radiator) was verifying absolute phase of each piece of equipment. We had non-polarized 2-prong power adapters for each power cord so we could plug each component in one way or the other. Leaving the preamp as a starting point, we reversed plugs on each other component until switching any of them degraded the sound. It started off slowly, as we didn't know which ones were not correct, but in the end, between the preamp, both power amps (the system was biamped) and CD player. When completed, reversing any plug caused an issue. The CD player was subtle, but he power amps or preamp were very easy to hear the difference.

[david k]

Tim is discussing absolute phase in recordings not the electrical wiring of your outlets and equipment, very different things.
david

[Steve Lefkowicz]

That's what I figured, and thinking back Brian referred to it as absolute polarity, not absolute phase.

[kcin]

Not sure if this is the same issue or not, but years ago when Brian Cheney came to my house to set up my VMPS RM-2neo speakers, the second most time consuming part of the installation (after mass loading the passive radiator) was verifying absolute phase of each piece of equipment. We had non-polarized 2-prong power adapters for each power cord so we could plug each component in one way or the other. Leaving the preamp as a starting point, we reversed plugs on each other component until switching any of them degraded the sound. It started off slowly, as we didn't know which ones were not correct, but in the end, between the preamp, both power amps (the system was biamped) and CD player. When completed, reversing any plug caused an issue. The CD player was subtle, but he power amps or preamp were very easy to hear the difference.

Audio polarity , absolute phase and ac power polarity are 3 different things

[MylesBAstor]

[MylesBAstor]

[Bill Hart]

I remember the phenomenon around the Wood Effect, and the list. I did hear differences on some records, but like many things, I guess I neglected to pay attention to it after a while. I did mess with the relative phase of tweeter, woofer and subs with my mid-horns, and that made a difference in the overall sound of the system and how it was wired. My phono stage allows me to push a button on the chassis to invert, but I don't. I guess I subscribe to Rob's observation that there are so many convolutions in the chain before it gets to the record, it's kind of hard to be "absolute" about it. I still have the book- I think it got packed again.

[Alrainbow]

Phasing is important for me to be set and left alone after. I am of the camp there is no perfection anywhere or anything in our holy order systems.
Geneisi has a wonderful document that lays out setting up speakers. His has examples of music and how it should sound when correct.
I also have cd for purpose as well. For me I find I am nkt phase sensitive and choose not to become either. We can teach ourselves to hear much better in obscure ways I feel. But at what price ? There was a thread on here that showed how we can hear water markings on tracks
it's true and I can tell not all but some. But the bigger point is why would we want to learn something that would take yet another pc of this hobby from us.
I have reworked and checked all possible phasing in my system beyond that I will not go further. To the best of my ability I know I am in phase in wiring and equipment
digital end I have no idea as I cannot clearly tell from my test tracks and will not go further then that. I find the more we read the less we enjoy

[JCOConnell]

what is a good record for demonstrating absolute polarity that most of would already have (i.e. common)?

[Bill Hart]

Casino Royale on the track The Look of Love- was the sax blowing or sucking? That's the one I remember-I think the Wood Effect booklet addressed it specifically, and it was pretty obvious. Also a pretty common "audiophile" warhorse back in the day.

[JCOConnell]

One of the many mods I did to my CJ PV-10A preamp was to add absolute polarity inversion to the front panel and remote. I rarely use it however.

[Alrainbow]

I won some of the genesis cd s and a few others. Hd tracks has a few from them as well. I have many odd to play with for me

[JCOConnell]

I notice both Capitol records and Analog Productions are normally inverted polarity. What happens if its an Analogue Productions reissue of a Capitol record? Is it a double inversion or non inverted polarity?