Absolute Polarity

[boogievan]

A technical or industrial standard is not meant to prevent consumers from using the relevant technology in wrong ways. Nor is it meant to educate professionals on correct operating procedures.

It is simply meant to make life easier in that if universally followed, anyone following the instruction manual for their home hi-fi gear would end up listening in correct polarity. If they wire the speakers wrong, their problem.

Dan Lavry's point is that carefully following the manual for one's home hi-fi gear might nevertheless cause the end user to listen to something with incorrect acoustic polarity if the pressing, for example, being auditioned was cut with incorrect acoustic polarity, and there's no switch to flip. A switch on the home hi-fi gear allows the end user to confirm if the recording (and gear/cabling) is (net) correct. It really only matters that it's presented correctly when auditioned. (Perhaps the studio heard it correctly but it still got bounced, cut, or dubbed out of natural acoustic polarity.) Switching on the fly allows one's brief auditory memory to compare the switched sound to the unswitched sound. When the treble percussion sounds sharper and the bass sounds fuller, the switch is correctly set. It's not a matter of personal preference. If you prefer the treble percussion to sound flatter and the bass to sound less full, you are free to audition in the incorrect switch setting, but you will know that it's a sonic betrayal of that which is acoustically natural if you hear it both ways (and remember these words). (;

Likewise in the professional end. It is not difficult to maintain absolute polarity throughout the recording production and manufacturing process. If people choose not to, their problem.

It's quite easy for the acoustic polarity to suffer during a recording's production since there are so many opportunities for it to become inverted. European tape machines like the Swiss-made Studer were pin 2-High. Ampex's ATR-102 meterbridge preamps were pin 3-High. The ATR-102's better-sounding, single-ended inputs (right next to the card cage) are pin 2-Hot, but you need a special connector to use the single ended inputs. Using a Studer to mix down through the balanced inputs of an Ampex introduces one common place where an inversion will happen if no one flips switches or uses special cables. If it's not corrected in the heat of the mix session, it will need to be corrected in mastering. If it's not corrected there, it can still be corrected by the end user during playback of the release if s/he has a stereo polarity switch on the preamp being used. Checking ø during production is good. But putting a ø switch on home hi-fi gear means that absolute polarity errors by major labels - which happen occasionally - can be corrected rather trivially.

A switch can introduce an element of preference. Personal preferences are entirely outside the scope of standard documents.

Personal preference is outside of the scope of correct acoustic polarity. If you can't hear an improvement by flipping the stereo polarity switch, either the loudspeaker crossovers mangle phase to the point of correctness being unattainable - or the listener's hearing is flawed. If you can hear the restoration of correct acoustic polarity with one deflection of the switch or the other, it won't be due to personal preference - it will be due to absolute correctness. This, everyone should prefer.

Polarity inversion switches are also frequently encountered on multiple channel mixing desks, to help counter phase issues when using multiple microphones under time pressure.

...I just watched a video with Sylvia Massey using a polarity inversion switch on the channel of the Neve console she was using to record the bottom skin of a snare drum. She said she did it because she was aiming another mic at the top skin of the same snare, so the mics were at least partially going to null each other if one wasn't switched to inverted (mic) polarity... She switched there not because she didn't have time to resolder the leads on the XLR connector for the mic. She switched there because it was very easy to do so and corrected the issue blamelessly. The drummer naturally hears the bottom skin moving away from her or his ears. So, in order to keep the bottom skin's recording acoustically correct, it should cause a negative voltage with the skin's positive pressure (caused by it approaching the diaphragm, initially, instead of secondarily). So, there are two reasons for switching, and she didn't have to disturb any connectors and could use the same proximity with each mic on the top and bottom, getting the sharp attacks she sought for (the) Melvins.

This is not necessarily the way to go for high fidelity recordings. Neither the polarity switch as a quick fix, nor the time pressure. I will openly admit I also have used it under time pressure, but it is far from the ideal way to do things. But if this is what the client wants from me, their problem. My job is to know what is ideal and advise accordingly, for those who do want to do things properly. Not everybody does and I respect their wishes and views.

What flaw is there with flipping such a switch?

An up to date standardisation is always a good thing for an industry and it does make life much easier if universally implemented. Polarity is just one of the several aspects.

There's no need for a new standard since the standard hasn't changed. Just look it up and implement accordingly - and, when that fails, flip (both of) the switch(es)! (;

What if some fan of hardcore punk music start manufacturing turntables spinning at 38 rpm and 49 rpms, because his personal preference is that everything sounds better when played faster?
Then I could cut master sat 30 rpm and not tell anyone about it, just a matter of preference. After all, who can really know if absolute speed has been maintained anyway? Isn't that why Technics added these sliders on the side? Just set the speed to taste...

Those sliders are primarily for matching tempos of different dance cuts when you use more than one turn-table with your Gemini, Sir. Nothing's stopping anyone from cutting slow or playing back fast, either. There's no connection between vari-speed and absolute polarity.


Boogie

[jesusfwrl]

Boogievan, I thin you misunderstood my post. I am not opposed to polarity inversion switches, I use them myself. I agree of course that there are several valid techniques that require one, like the Sylvia Massey example you mention. I was referring to the far more common practice of just flipping the polarity switch on a channel of a mixing console, when moving a mic a couple of inches would have been a far better approach (but in general I'm not the kind of person who would even mic up each drum individually on a kit, let alone using more than one mic per drum! In my experience, 2-3 mics on a good kit in a half decent room get all the punch one could wish for and I'm saying this as a drummer as well as an engineer. As much as I like the Melvins, their recordings do not do them justice, having had the opportunity to see them live on several occasions.)

My remark on the switches is simply that they are outside the scope of a standard for phonograph records and associated recording/reproducing equipment.

As for Studer vs Ampex, my point exactly about why it would be good to have up-to-date, internationally accepted standards, in our industry. We currently have way too many, outdated, often conflicting standards, often in different languages, which are routinely ignored by most professionals (which is why the Studer/Ampex situation can happen).

My suggestion for an up to date standard is NOT about polarity, this is the ONLY up to date standard we have, at present, covering phonograph records!

As an example, what is the standard reference level on disk? Or how about dimensional standards and tolerances? Each standard ever published covers these, but they rarely agree with each other.

As for vari-speed, obviously there was no connection to absolute polarity, other than being yet one more thing you could adjust to taste. Which is why the standards documents do specify the STANDARD speeds, but do not specify the possibility of beat-matching for DJ's, as this lis outside the scope of standardization.

What I am proposing is a standard for "Phonograph Records and Associated Recording and Reproducing Equipment", based on all the DIN, BS, JIS, NAB, AES, RIAA, etc, standards, but actually reaching some conclusions on which version of each point is best serving our present industry, with the participation of as many of the currently active professionals and organisations as possible, so it actually stands a chance of being widely (and internationally) accepted.

Unlike the 60's/70's, when most records were pressed locally in any reasonably industrialized country, nowadays we truly do have a large scale "international programme exchange", where records know no borders, and likewise with rec/repro equipment. We need ONE standard, reflecting the current needs of the industry, that all of us would happily conform to.

[jesusfwrl]

Looks like my proposal for updating standards has found an attentive audience:

RIAA TO SET UPDATED STANDARDS FOR VINYL

We are very pleased to announce a collaboration between The RIAA (The Recording Industry Association of America), ‘MAKING VINYL’ and the Media-Tech Association with the goal of updating the standards for vinyl records.

Manufacturing specifications for vinyl were last updated in 1978. The advent of new manufacturing technologies and resurgent popularity of vinyl prompted music industry leaders to review existing specifications and evaluate whether updated standards could help further advance the vinyl market.

How might new standards help?

Vinyl records are a premium product -- a high-quality experience is essential to retaining consumer confidence and meeting consumer’s expectations.
Minimizing counterfeit products in the marketplace.

Workgroups will begin forming in the coming weeks with a target date of early 2019 for possible standards.

More information and progress will be released during the Making Vinyl Conference Oct 1-2, 2018 in Detroit.

I will be very excited to participate in this new effort.

[boogievan]

A technical or industrial standard is not meant to prevent consumers from using the relevant technology in wrong ways. Nor is it meant to educate professionals on correct operating procedures...

If the professional isn't sure, s/he consults the standard. But this isn't very esoteric or technical. It's just about whether or not an atmospheric compression that reaches a microphone diaphragm causes an atmospheric compression from the loudspeaker, or a rarefaction.

...It is simply meant to make life easier in that if universally followed, anyone following the instruction manual for their home hi-fi gear would end up listening in correct polarity. If they wire the speakers wrong, their problem.

Again, as Dan Lavry points out, the industry occasionally release pressings with inverted absolute polarity, despite there being a standard, so, if the consumer has merely plugged the wires of the cartridge into the tone arm and the cables of the tone arm and RIAA preamp and amp and speakers correctly, there still is the possibility that s/he will hear the recording play with inverted acoustic polarity.

Likewise in the professional end. It is not difficult to maintain absolute polarity throughout the recording production and manufacturing process. If people choose not to, their problem.

When they don't maintain or at least correct absolute polarity at the output of the recording chain, it's usually because the engineer has erred. It's not likely to be that s/he chose not to get it right, since the natural acoustic polarity sounds better, naturally. (If a strident sound wanted softening, there are processors to fix it.)

A switch can introduce an element of preference. Personal preferences are entirely outside the scope of standard documents.

With respect, if one thinks of the absolute polarity switch as something that has a preferred position, then s/he's not understood its purpose. However, if one is mindful that s/he doesn't know whether or not the new recording being auditioned is in accordance with the standard or not, then s/he will already know that she doesn't yet know what switch deflection s/he should prefer, so this will not be an issue.

One doesn't 'set and forget' such a switch. E allore, there can be no preferred position for all recordings because not all recordings are released with the same adherence. So, one must listen in order to determine if the attacks of hi hats and snares very-very slightly rise in pitch when a given switch deflection is invoked, or very-very slightly fall (in pitch). The preferred position for a given recording should be the one which makes the hi hat or snare attack have a slightly higher perceived pitch, as this is the polarity that causes a compression, rather than a rarefaction, because compressions of the atmosphere will make a slightly higher µ-voltage with the ear's cilia. If one is uncertain about the change in pitch, the playback system is flawed, or the multitrack recording that got mixed down was so mixed up by phase issues as to render the task of discerning the correct deflection for that mix impossible.

Polarity inversion switches are also frequently encountered on multiple channel mixing desks, to help counter phase issues when using multiple microphones under time pressure. This is not necessarily the way to go for high fidelity recordings. Neither the polarity switch as a quick fix, nor the time pressure. I will openly admit I also have used it under time pressure, but it is far from the ideal way to do things. But if this is what the client wants from me, their problem. My job is to know what is ideal and advise accordingly, for those who do want to do things properly. Not everybody does and I respect their wishes and views.

If the monitoring is good, and the recording doesn't present a hodge podge of phase relationships, it will take very little time to hear the correct acoustic polarity (as described in this reply, above). Again, since the correct wiring standards fail to guarantee that a master will have correct absolute polarity, it's the only way to be sure. An asymmetrical test tone can be viewed on a 'scope, but one still needs to judge the master by ear. Some DAWs show the asymmetry of the digital audio waveform, but it can't be relied upon, since some instruments and voices have more energy in the half-cycles of rarefaction. The ear is the final arbiter, and it must be presented with a choice between the two available absolute polarity switch deflection options before it can be sure of the preferred, natural, correct switch deflection.

An up to date standardisation is always a good thing for an industry and it does make life much easier if universally implemented. Polarity is just one of the several aspects.

Since our hearing hasn't changed and the practice hasn't changed, then the old standard is already 'up-to-date'. We can refer to it whenever in doubt. No one should 'publish' the same standard as if it's new, even if s/he might (academically) 'perish' for want of novel ideas.

What if some fan of hardcore punk music start manufacturing turntables spinning at 38 rpm and 49 rpms, because his personal preference is that everything sounds better when played faster?
Then I could cut master sat 30 rpm and not tell anyone about it, just a matter of preference. After all, who can really know if absolute speed has been maintained anyway? Isn't that why Technics added these sliders on the side? Just set the speed to taste...

Absolute pitch has nothing to do with absolute polarity. The pitch of high treble attacks (hi hats / shakers / snares, etc...) will be a little bit higher when presented with their natural acoustic polarity than if reproduced with an inverted acoustic polarity, but that's relative pitch - not absolute.


- Boogie

[boogievan]

I started thinking about the absolute polarity (and, therefore, repro's effective acoustic polarity) of vinyl records after finding a website that posts albums that are out of polarity from the standard. One of them was Sketches of Spain (original pressing). I bought a copy online and checked the playback. The muted trumpet in 'Will O' The Wisp' (which, incidentally, is beautifully presented in the film, El Amor Brujo, but with a different arrangement, and sung...) leaps out and has a slightly brighter, more natural timbre when I flip the absolute polarity switch for both channels on the monitor console. Not so with most other LPs, however, such as Kansas / Point of Know Return and Steely Dan / Aja (originals), which both have a slightly higher-pitched (slightly less 'muffled') sounding hi hat when the abs. pol. switches are in their 'fully upright and locked positions' (i.e., agreeing with the standard).

I just checked the old mono (6-eye Columbia logo) pressing of K. O. B. as well as the amazingly well-cut and good-sounding, new (mono) treatment by Ryan K. Smith (on 180 gram, with the same artwork as the original jacket and labels), who seems to have used a VMS-80 and Spitz-modified ATR-102 (as a -'101') preview deck - the time base of the RKS cuts is noticeably more stable than on the original pressing. The original pressing has a lot of groove-kiss on side A, but the RKS cut has almost zero*. That cut uses a 2-mil groove, however, and the original uses 2.5. The level sounds pretty much the same, but I didn't measure and only checked out 'So What', so far. The absolute polarity is also, non-standard, as evidenced particularly by the way the ride cymbal slightly changes pitch when both channels' abs. pol. switches are deflected, rising for the o. o. ø. position... So, I wonder if Columbia (or Miles, himself) deliberately had his cuts modulated inside-out - causing, on playback, atmospheric rarefactions for recorded compressions... - because it 'smooths out' the trumpet's 'honk'. I prefer it in the natural polarity, because I like the surface features of the trumpet's peal, so I listen with the two switches 'flipped' (to the 'non-preferred', but willingly avoided deflection), but I can imagine someone thinking that it sounds 'way more smoother' in the inverted polarity - in air - because the trumpet is not inherently dulcet, like the shawn, for example - and muting the trumpet doesn't really help, if your goal is 'sonic pillow'.



- Boogie




* On the original as well, where the outer groove wall appears to make contact with the inner groove wall of the previous platter-turn, there is somehow the slightest bit of daylight 'land' between them if you look with 150x instead of 75x. However, this seems to be something that can happen during pressing. It doesn't show the (premissible) overcut that would have been seen in the lacquer, but you know that contact was made because one of the walls loses a little width right where they appear to touch (at 75x). I've seen it on my own cuts when the pressing is later viewd under the mic. If the groove kiss is very minor - 'kissing, but not 'f-ing' - then playback won't tell because the width of the groove, even after losing a tiny bit at the top of the smooch, remains several times greater than the pickup stylus tip.

[GeorgeZ]

There is a virtually standard by georg neumann which says that:
"positive half-wave of a lateral recording has to move to edge of the record"

knowing the relation between mono and stereo you can now define every polarity in your system.
might be important for correct working of your vari-pitch.

Lukas

Hello all,
I would like to do a closer look at that mentioned "standard by Georg Neumann". Is it possible to find it anywhere? Which Neumann manual or tech-doc should be searched to find anything written...? Thanks for any hint. Unfortunately, I have no time to read all the docs and manuals sentence by sentence so I hope some of you know the exact place.

[dubcutter89]

Hey Jiri!
Don't know the exact spot now 9 years after I posted this, but I think it was in some old document when styli moved lateral only.
Had a look now at quite a bunch of neumann documents and didn't find again. Also no time to read sentence by sentence...
But I found the same information by ortofon, polygram, zuma...and even my electrical engineering book I had at school showed this.

Life is relative, Phase is absolute ???

When I find the information again in the holy neumann literature I will copy and send to you!
(And if have trouble with phase maybe toggle the phase switch on the VSA80-PC-board, that's what the 1979 manual says after reading one million lines

Lukas

[subkontrabob]

Here is a figure presented in Nygaards' "Ortofon book", contained in Tony Batchelor's ebook.

20200620_225117.jpg

[subkontrabob]

I neglected to provide a link to Tony's book.


https://www.amazon.com/dp/B01IFBODS0

Here is a figure presented in Nygaards' "Ortofon book", contained in Tony Batchelor's ebook.

20200620_225117.jpg

[subkontrabob]

The thread about Tony's book can be found here:

https://lathetrolls.com/viewtopic.php?f=4&t=6701