How often do you use the polarity invert switch?*

¡ɹǝʌǝN

 

Why do it, you mean?

For the spooky reality you get when it's right. One of the big things for me is the reverb - natural or in-phase chamber/plate/spring. When the polarity is inverted on playback, you hear the source and its associated reverb but you don't get the effortless dimensional reality you get when the polarity matches the original source hitting the microphone.

Also, timbre suffers with inverted polarity. Harmonics on a piano that should zing metallically sound softened and less detailed, vocals lose their immediacy, bass can lose its fullness, I could go on...

 

When I had a linestage that offered absolute phase inversion, by remote control, I played around with it a bit. Yes, on some recordings I could hear and obvious difference--some of the times I had a clear preference for one setting over the other and other times there was a difference, but preference was not as clear (e.g., the piano might sound better with one setting, but the vocalist did not sound as focused). Even where I had a preference, this would change from one recording to another (even from the same label), and in fact, there could be changes from one track to another. Because the differences seemed small, I preserved sanity by figuring out which setting I generally preferred and left it at that setting (because of the incredible flexibility of the Levinson No. 32 linestage I used, that single setting was no inversion for my CD source, and inversion for my vinyl source).

Because some components invert absolute polarity and some do not, and this is the case all along the entire chain of equipment in the studio and mastering chain, what you end up with at your speaker is essentially a crapshoot. I bet that many multi-track recordings will have certain instruments recorded in one phase and others in the opposite phase and that might be the case even with different miking of instruments for live recordings. Also, some speakers are designed to preserve the time/phase relationships of the drivers, but, most do not, and I would bet this will affect the audibility of absolute phase changes.

You don't need a phase switch to experiment on how audible an absolute polarity change will be to you on your particular system. You can find test CDs that have been carefully recorded to have a consistent phasing of the various microphones and which play back the recording in both inverted and non-inverted polarity. I have a Chesky test CD that does this with both a single instrument (trumpet) and a recording of a jazz ensemble.

 

Some commercial multi-track recordings are in-phase - for example, EMI were still fastidious about phase in the 60s.

 

This may just be me, but most CDs sound better to me in Absolute Polarity and most LPs sound better in Inverse Polarity. The best way to judge is by degree of centerfill in the stereo image since correct phase should produce that effect. There is a major complication however and that is the frequent use of multimiking and pop music mixing practices. Both of those tend to introduce complex polarity effects that don't translate to Absolute/ Inverse Polarity very well.

 

I had a friend, a rep in the pro side of the electronics industry, who was extremely sensitive to absolute phase. He'd walk in a room with music playing and say that the polarity was reversed. Uncanny. He complained reversed polarity hurt his ears.

 

Try these (on original CD):

Prince - Dirty Mind
Santana - Amigos
Van Morrison - Astral Weeks

They come to life on my system when the DAC is set to 'Normal' - I think my system inverts somewhere as the majority of things sound better when it is set to "Inverted".

 

Steve,
I am familiar with checking for correct polarity by checking signals with an oscilloscope, using an asymmetric signal. How would you employ a "cheap voltmeter" to check for this? Does it require a special test signal that produces a DC bias that can be read on the voltmeter?
I just did a quick google, but only came up with pages on AC mains polarity checking.
The only thing I can imagine would be the "quick and dirty" speaker phase check using a battery across the connections to produce a DC impulse. However, this may not be safe on line-level inputs.

 

Both the Santana (1990) and Van (1989) sound alright in normal setting for me. Reading the replies, I would guess that people perceive different things concerning polarity. I was really just more interested in finding whether the rate of usage correlated with mine.
PS: I used the term phase invert only because that's how my amp manufacturer Jeff Rowland refers to it.

 

To answer the original question: I will ocassionally use the Phase Reverse switch on FM broadcasts when the tuner must be set to mono on weak stations where there is too much noise in stereo. In this way, reversing the phase creates a "simulated stereo" effect.

I once owned a Pioneer receiver ( SX 50, IIRC) which had a switch labled "Simulated Stereo" which I believe did exactly the same thing as Phase Reverse on earlier equipment.

Other than for that, I really would not miss it, frankly.

 

Steve, at the risk of making a tricky issue even tougher, aren't you confusing two different polarity inversion issues? There is polarity inversion of the AC line, which can be tested with a voltmeter and is huge, as you say, and polarity inversion of the audio signal, which is what the rest of your post and this thread is about.

First, let's look at the AC polarity issue. While not the subject of this thread, it is an often unconsidered way to make your stereo sound much better. A normal two spade AC plug has hot and neutral connectors. On the hot side of the plug we'll find a voltage swing of plus or minus 115 volts. The neutral side is what this voltage swings around. Since we only need electrical potential - the difference between the two levels, neutral and hot - it makes no difference which way the plug is in the wall socket. You can take an AC plug and put it in either way into a wall socket and the device will work. The difference between the hot and neutral sides of the plug are the same in either direction.

But that's not what the electronic device's designer was considering when he or she built the piece. He or she designed a device with a power supply that had specific connections for hot, neutral and ground (the third connector on many AC plugs). What you are rightfully recommending is that we get our devices plugged in so that they agree with the designer's plans. The hot spade on our AC plug should wired to the designer's hot connection inside the power supply of the device, as should the neutral spade.

To run this test this you'll need some basic stuff:

1) A cheap AC voltmeter. A $10 one will work just fine.
2) An AC cheater plug, the gray one you see in the hardware store that allow you to plug a three pin plug into a two pin outlet. One of the two spades on the cheater plug will be bigger than the other so you'll have to either file, grind or cut it down so that the pins are the same width.
3) A bottle of bright red fingernail polish.

Disconnect the device under test from everything, including all interconnects. If the piece uses a three prong plug, use the AC cheater plug to turn it into a two prong one. Find a good screw on the device that goes into its chassis. Set the voltmeter to read AC volts. Plug the device in the wall and turn it on. Carefully put one probe of the voltmeter in the third, ground terminal of the AC outlet you are using. Touch the other probe to the chassis screw on the device. Your meter should read a certain amount of AC volts. Now flip the AC plug around 180º. Measure the AC voltage again between the ground socket and the chassis ground of the device. One of the two readings will be lower. This is the way your device should be plugged into that outlet.

If your house or apartment is wired correctly, and the device is also wired correctly, the smaller of the two spade connectors will be the hot ones. I've lived in enough old houses to know this can often not be the case. I've also owned gear where this was not the case. That's really what we are checking here, making sure everything is wired correctly in your house and for your equipment. You can't assume it is. You can check your AC outlet using a polarity tester you can buy at any hardware store, of if you aren't scared of electricity, by using the voltmeter to measure between the third ground receptacle and the two spade ones. The smaller spade receptacle should be hot and read 115v or there about. The larger one should be neutral and read zero. If you outlet is wired backward, use the fingernail polish to indicate this, or the adventurous among you can shut off the breaker and rewire the outlet.

Use the red fingernail polish to mark the device's plug so that you know which spade goes into the smaller receptacle on the AC outlet. That should give you hot to hot. Check all of your devices and outlets. Don't be surprised if you find some of them backwards from how they should be. You may need extra cheater plugs to fix incorrectly wired three prong devices.

When you get this right, the difference can be extraordinary. Hum goes down. The image opens up. Everything just sounds better.

The second type of polarity inversion, that of the audio signal, can come from all the reasons you bring up but also can be generated inside an amp. Amps have stages. Amplification is a bucket brigade affair. Every amp stage inverts the absolute phase of the signal. A good amp designer will make sure the polarity of the signal going into his or her amp is the same as the one leaving it. Overall, the absolute phase remains the same. A sloppy amp designer won't and their amp will invert absolute phase.

For more on this, including ways to both test and compensate for absolute phase inversion, please read this excellent and short white paper by a favorite store owner of mine, Galen Carol:

Absolute Phase: A Prerequisite To Optimum Performance

 

Wow. I can't believe I forgot about this approach. As I read it I recall the same exact steps. I did this many years ago on my system when I was tweaking quite a bit - I was single and had A LOT OF TIME. But this approach to the electrical side of equipment did exactly as GGerm says. It opened up the sound and lowered hum. I think it helped to make the sound more (vague audio reference coming) "coherent".

 

For those of you who listen to music on headphones from your Iphone/Android the music player app Neutron has a polarity switch in it's programming. It's in the Audio Hardware menu. For me, changing polarity does as others have said - focuses the centre image and tightens bass. I think it also helps soundstage. As others have noted - echoes and microdynamics are helped with the correct polarity.

Neutron is very well supplied with variables and is described as a device that works in the root structure to shape sound. I don't have money in this app, just like it when I use my headphones.

 

"If you care about the drum sound, push the button if they sound better one way or the other but REMEMBER, the lead instrument or vocal is very important and they need to be correct, even if it makes the drums less-vibrant sounding for you."

Agree! Especially lead female vocals.

One example.
Jennifer Warnes CD, "The Hunter".
Track #8, "Way Down Deep"

http://www.6moons.com/industryfeatures/polarity/polarity.html

http://www.stanrickermastering.com/polarity.htm

http://www.positive-feedback.com/Issue1/cjwoodeffect.htm

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1122855422&openfrom&1&4#1

 

I use mine whenever the poles flip.

 

Hi Steve, just did a quick search for a text inverter, typed the word in and copied the inverted text across here. Simples!

 

I hope people won't risk electrocution trying to get their mains polarity the "right" way round out of some misguided notion that it will improve the sound. AC power does not have polarity. The whole point about AC power is that the electrons run backwards and forwards between the two wires alternately at exactly the same rate - that's why it's called alternating current. So obviously it doesn't make any difference at all which way round the wires are because the current will still be running alternately backwards and forwards between them in exactly the same way.

Once the current reaches the rectifier in your amplifier, that's when things change. The job of the rectifier is to convert AC to DC, which means getting all the electrons running in the same direction instead of backwards and forwards. The AC inputs on the rectifier have no markings as to polarity because it makes no difference at all which way round the wires are connected - the electrons are always running backwards and forwards between them at the same rate. However, the DC outputs on the rectifier most definitely do have polarity because once the rectifier has done its job, the electrons are flowing in one direction only, from positive to negative, and from this point onwards polarity becomes very much a reality.

Whether or not you can hear inverted polarity is another question but AC power has no polarity at all so please don't (literally) kill yourself trying to get your mains electricity the "right" way round!

 

A little less than never.

 

Seems like a good approach to me, I think I use it even less.

 

The only time I'd use it is if I had an amp which inverted the absolute phase, which does happen. A good reviewer who benches the amp will mention it if he finds the amp inverts polarity. In this case, it's a set it once and forget it situation. That I have done in the past and would do in the future.

I explored polarity inversion more deeply in the late 1970s with Sheffield Lab direct to disc records. A phase inversion warning was printed on the Dave Grusin - Discovered Again! record, still one of the best sounding LPs I own, with Grusin on keys, Ron Carter on bass, Harvey Mason on drums and Lee Ritenour on guitar. It was engineered by Bill Schnee and produced by Lincoln Mayorga and Doug Sax, and of course mastered direct to disc by Doug Sax. Because of high powered names like those at the helm, I paid attention this note:



I tried switching my speaker wires and while it made a difference in the sound, I'm not sure it was any better. Back then I might well have owned gear incapable of reproducing the difference plus I was ignorant to the fact that amps themselves could invert absolute phase. Who knows if the various pieces I was using then, mostly G.A.S. amps and preamps but a lot of other stuff, too, inverted phase?

The biggest problem then and now is that it's a pain in the ass. I don't have a phase inversion switch so I'd have to do it at the speakers. With bi-amping and a sub, that's a lot of switching for just one record. I want to listen to music, not futz around with gear all night.

Lastly, and it's something Steve mentioned upthread, a case like this note on the Sheffield Lab record is unique. You don't find warnings like this and so if you are going to go down the rabbit hole chasing absolute phase, what instrument do you do it for? Most recording engineers never consider getting all of their microphone and line feeds in phase with each other. You may have the bass guitar flipped in phase, which can be audibly noticeable, but if you correct for that, the lead vocal is now polarity inverted. What do you listen for? Where do you make the decision? And at what point do you just say screw it and play the record?

Phase inversion is something an audiophile should be aware of. It can make a difference. Some people are acutely sensitive to it. I'm not. Watching out for it and correcting for it when necessary is a tool in my kit bag but nothing more than that.

 

It´s even more of a rabbit hole these days when some ADCs are inverting, some DACs are inverting, so for me the only thing I can do is just to forget about it.