Polarity??

[Coytee]

Yesterday I was at someone's house listening to his stuff (and today, he has just left mine, listening to the Jubilees)

While listening, he was talking about reversing the polarity of the speaker. He was not talking about taking them out of phase, they are already presumed to be in phase.

He was talking about reversing BOTH the +/- on his amps under the theory (facts?) that as something is recorded the initial punch of a drum might want to drive the woofer forward. During the process of the sound from CD/LP to preamp and amp the signal might get inverted. If the signal is inverted then it would drive the woofer BACKWARD instead of forward on the initial hit.

By swapping it around you can get the speaker in the right polarity with the signal.

He also said that some amps will take a signal and output the SAME signal (polarity) and a different amp might have an inverted signal on the outputs...it all depends on what's going on inside the amp. (I admit to not fully understanding all of this)

I found his comments interesting (he is also an electrical engineer so who am I to doubt??). so, I found his comments interesting however I'd never heard of that before. Then as I was looking at his equipment and many of his cd's... he has gone to the extra step of affixing a piece of paper over each amp with a "+" or "-" on it so he knows the phase of that amp. He has then gone and put a + or - on the outside of his cd's so he can listen to one and know right off the bat he needs to flip his speaker wires (on BOTH amps, so the phase stays in place). On a different disk, he knows he needs to flip the wires back.

I didn't know what to make of all that and today when he was over at my place, he was playing around with my EV Dx-38 and all the sudden he says "THERE IT IS"

Huh??

Seems the EV has a polarity function built in where I can have it "normal" or "reversed"!!!! Exactly what he was saying!!

All the sudden everything he has said was independently reinforced by seeing this and I realzed that I don't recall ever hearing this topic brought up here. I thought I'd at least mention this and see what happens conversationally.

Oh... and on the side... during this process he thought the Jubilees sounded fantastic but something was befuddling him... I made a joke about them being out of phase with each other and after laughing at my "joke", I looked at one of the wires and noticed the "writing was on negative". Since I always put writing on red/positive... I was curious. I looked further and indeed, they WERE in fact out of phase.

Sigh...

[:$]

So, aside from my humiliation of having them out of phase... what's up with this polarity stuff?

[mas]

Some devices do invert polarity, but most adjust for it on the output by reversing terminals, etc. Some may not.

Polarity is the movement of the driver with respect to output. You want it to move forward with the application of a signal - not backwards.

I think we have covered all of it that we need to. []

Although that certainly does not mean this thread can't go on for days.

Say "hi" to Chloe for me.

[Guest " "]

Some pre-amps invert the output and specify to invert the speaker wires.

intrestingly, a 1:1 input isolation transformer as in the type that can connect RCA to XLR could invert the phase if not wired correctly.

[LarryC]

Manuals and specs of some preamps (and maybe amps or other units -- what's the DX-38?), may indicate whether the unit inverts polarity. In some preamps, the phono stage inverts polarity while the line does not or vice versa, in which case the owner would have to invert polarity at the tonearm leads to the cart to make polarity come out the same for all sources. In at least one preamp, the MC phono stage inverts while the MM phono does not!

[PrestonTom]

What you are referring to is known as "absolute polarity" (not to be confused with relative polarity between drivers in the the same cabinet - which may be done intentionally, and not be confused with reverse polarity between cabinets, which should obviously not be done).

Some pre-amps will have a switch to accomplish what MAS has mentioned. The topic is contoversial since up until recently there were no standards on what the polarity should be in the recording and playback chain (there are a large number of opportunities for it to get "switched"). The controversy is increased since there are a few psychoacoustic data that suggest you might be sensitive to absolute polarity in certain cases (this is known as the "Wood effect"). There are plenty of "informal observations" where folks claim they hear the difference (and wax poetically about the flavor of the percept).

It is not a topic that gets much formal research (for various reasons). Some folks get very hot under the collar about this topic. If it does exist, the effect is subtle and most folks will not hear any difference.

I know I have never lost any sleep over whether I should swap the speaker wires.

Good Luck,

-Tom

[Speedball]

I will be asking questions in the future about Polarity when it comes time to get a dedicated preamp. Just recently I've been reading about some preamps do and others do not change the polarity. Still more to learn about this audio stuff:[8-)]

Like Tom says, maybe not worth losing sleep over.

[Coytee]

hnmm... you brainiacs make this seem as though it's as common as butter on bread (and maybe it is?)

Guess I need to get out from under my rock more often. I've never heard of the polarity being reversed in any capacity.

[:^)]

[Coytee]

Been thinking more about my ignorance. Was taking me a long time so I took a break to ask this...

Is there some way you can test and "know" that two speakers are setup properly with regard to polarity?

I've got a HP volt/watt meter (I think it's called?) It's about 40 years old, has some probes and you can evidently use it to measure milliwatts or millivolts or something like that? I bought it on the suggestion of Al K so I could test the output of an amp and find a set number for its output...then go to my McIntosh MC-30's with their variable inputs and adjust them so their output matched the other amp.

Though I ultimately sold the 30's, I still have the HP unit.

If that's not the right tool to "prove" polarity, what might one use and how?

[mas]

Richard,

Actually, the topic should be transparent to the end user and normally you should not normally need to be messing with it. And if the designers of the gear have their acts together you should not have to deal with it. The switch on the crossover simply allows you extra functionality depending upon the configuration that you are using - as it assumes more configuration possibilities than most consumer gear - configurations that most folks will never encounter.

It is often adjusted prior to the final output (eg - an inverting circuit is hooked in a reverse manner so that the output is in the proper polarity), as there is only one proper polarity for a dynamic speaker in a standard application.

Don't feel bad for asking a good question. (Even though we may have a bit of fun hassling you! And now all you have to do is to find a good question to ask! Sorry buddy, I simply couldn't resist! [])

If you do encounter such a problem on standard consumer gear, that is a great excuse and opportunity to let Chloe get a little extra exercise and to vent all of her frustrations! []

[mas]

Yes, there is gear that will test for it. All of the time based gear will indicate it with regards to the impulse test. Heyser spirals will also indicate it directly.

The easiest way to test is to use a battery. A nine volt battery on a dynamic woofer or midrange will cause the cone to move forward or backward. Note the connections that make the cone move forward. On a horn you will need to use an impulse or similar test.

Also, if the two speakers are not in proper polarity, you will note in in a lowered bass response - as that is what you are testing for when you test speakers for being out of phase relative to one another. But you are more properly testing them for being out of polarity.

Take a look at the attachment for ore info than you ever wanted about polarity.

Polarity101.pdf

[Coytee]

Yes, there is gear that will test for it. All of the time based gear will indicate it with regards to the impulse test. Heyser spirals will also indicate it directly.

But I gave up my Spira-Gyra set decades ago so I can't draw the pretty circles anymore

The easiest way to test is to use a battery. A nine volt battery on a dynamic woofer or midrange will cause the cone to move forward or backward. Note the connections that make the cone move forward. On a horn you will need to use an impulse or similar test.

Ok...so now you're working on my last nerve!! A nine volt battery huh? Ok, so let's just say that I slap a 9 volt battery on the leads...heck... let's say I slap a zillion volt battery on the leads... are YOU gonna be the one to stick your head inside that convoluted bass bin to see which way the bugger is flapping? Besides... if I stick the battery on the leads and for arguments sake + to + and - to - gives me an outward thrust of the driver, isn't that only telling me the speakers are wired the same? Don't I still have the issue of knowing what the amp is putting out on the + lead? I'm understanding that one can presume it's in fact a + however, I'm also understanding that it isn't 100%?

Also, if the two speakers are not in proper polarity, you will note in in a lowered bass response -

Interestingly enough, we did the reverse polarity (using the Dx-38) and he said he couldn't tell any difference, that the bass sounded fantastic. It was just after that, the out of phase bass bin was discovered. A couple weeks ago I was piddling around with ALL the wires. Seems that me piddling with wires is a bad thing!!

as that is what you are testing for when you test speakers for being out of phase relative to one another. But you are more properly testing them for being out of polarity.

It might break your heart to know this but between yesterday and today, I've shaved Chloe, Hattie and Otis. I shaved Chloe first and frankly, she's a bit hacked up looking. By the time I got to Otis, I started to get the hang of it. Chloe's mad at me now.

[mas]

Silly boy...

Why do I have the sneaking suspicion that your wife would only shake her head in bemusement if she walked in and saw you with your head shoved into the bass bin... life with a 'challenged' child...

OK, so if you want to know if the signal chain is wired correctly, either have someone take an impulse measurement - call up UTK, someone up there is sure to have a TEF somewhere!

Or use a mic and tap on it and watch the cone movement. It should move forward with the tap. Of course you have to be able to see the driver, so stick your head back up....self control, Mark, self control... the bass bin.

OK, enough fun. Take a look at the attachment. It may be a bit much, but that is where it might make sense for a few of us to get together and invest in a cheap time based measurement tool that we can all play with and share ideas and insights into it

(its hard talking about a tool that others do not have - so lets fix this!)...Hint! Hint! Anyone interested? PM me and we can explore ideas...

[LarryC]

Richard,

You have a gift in that polarity switch on the DX-38 or whatever it is, if it changes the polarity of both entire speaker systems -- just flip it while listening to cymbals or trumpets. To my ear, when I've been able to hear a difference, one way has sounded odd, hollow and withdrawn, while the other has sounded forthright and "right." I don't recall hearing a difference in the amount of bass (not like if the speakers were out of phase).

If you can't hear a difference, don't worry about it. I think I do in my setup, WHEN I test for it. However, I supposedly have relative inversions of polarity between my sources, and I think I recall that some recordings have reversed polarity vis-a-vis others so that it may not be possible to make a consistent difference anyway. Unless you hear revelations, I'd just forget it.

[pauln]

[Islander]

The last time I used the auto setup on my Yamaha receiver, it declared that both La Scalas were "out of phase", while none of the other 5 speakers (center, surround and surround back) were. Since the cables were connected correctly, does this indicate a polarity mixup?

According to the manual, some speakers will show up as out of phase even if they're not. Is there something odd about horn speakers in this regard? When the program checked the distance (in order to set the delay), I was interested to notice that it measured the distance from the listening position to the diaphragm of the squawker horn, not to the front of the speaker (a difference of nearly 2 feet). Obvious when you think of it, but with typical speakers, I'd measure to the dust cap of the midrange driver.

The YPAO program seems best at measuring speaker distances from the listening position, while the other parameters like speaker size and level are better set manually, in my experience at least.

[Speedball]

The man has a sense of humor: Lefty Loosey & Righty Tighty

[pauln]

The man has a sense of humor: Lefty Loosey & Righty Tighty

For those in the 100% club, polarity has to extend to the screws...[*-)]

[mikebse2a3]

Hey Richard give me a call.

I might can help you out with some testing and listening tests if your interested.

mike tn

[WMcD]

There has been some research about absolute polarity. I've read about the research rather than the research itself. You can Google around.

The issue was whether our ear-brain combination can detect a reversal of polarity of the waveform of music.

These tests used a system which is known to not invert polarity, but which can be inverted at will (pretty much like switching wires around). The result is that our ear-brain can not detect that inversion. But see below. 3)

There are a few reasons why polarity inversion is difficult to detect.

1) Most music is symetric in waveform. So flipping it over does not make a difference. There are exceptions. One, as you'd expect is the hit of a drum. The pickup mike could be behind or in front and the waveform of that impulse is not going to be symetric even it is reversed by mike location. Consider a tympany is hit away from an overhead mike. A kick drum is hit toward a mike in front. None the less, this doesn't seem to make much of a difference.

2) Our ear has the little cilia inside which fire the nerves. Apparently they don't individially sense whether they first move one way, or the other.

3) The tests show that if the music has an asymetric pattern, then the ear-brain can detect the reversal of polarity. But apparently this requires a very specific waveform and the difference is subtile.

- - - -

This whole subject came up because people pointed out that even if our playback systems honor polarity, we really don't know what is going on in the recording chain. So it could be worthwhile to fool with playback polarity to reinvert an inverted recording. I believe nothing much was detected. E.g. no one said, a-ha, now it sounds "correct" after I made that correction.

- - - -

There is, though, much to be said for inverting polarity for one driver when a complicated crossover network is used. In the crossover region, one crossover can shift the signal 90 degrees minus and the other can shift it 90 degrees plus. So you get a notch in crossover region. If one of the drivers are inverted in polarity, the notch goes away. The Heresy crossover was changed for this reason and you can find the mod in a Dope from Hope.

- - - -

The time delays caused by horn length can create a similar problem.

- - - - -

I built a 15 inch Jubilee and a treble horn, and 2nd order crossovers. I tested with an LMS system. There was a notch in the crossover region. It was narrow and not too deep, but there. And reversing polarity took it away. None the less, I ran them with normal polarity.

One reason is that the notion of polarity inversion to correct the small problem gave me the engineering heebie jeebies. Ya, I know, that is contrary to theory that it can't be heard. Another issue for me was that even if the crossover problem is solved for that speaker, we now have to consider how it works in interactions with the other speakers in the system which are not identical to it.

Gil

[Coytee]

Hey Richard give me a call.

I might can help you out with some testing and listening tests if your interested.

mike tn

Hey Mike...

Late getting back to this/you. I'll probably do that once our seminars are over and it quiets down a bit. (we're halfway through as of today)

Another thing I might do is simply play around with it. I've taken a setting on the Dx unit and copied it to another location with the second location having the polarity reversed. Kind of easy to flip around and see if I can tell any difference.

By the way, I PRESUME I would do that on the bass bins as opposed to the K-402?