Using battery to test phase - question about tweeter phase

It seems obvious enough that using marked or bi-coloured wires should eliminate any mix-ups when it comes to connecting speakers in phase, but I recently learned the value of doing a very quick and easy check with a 1.5 volt battery.
I hooked up an older pair of speakers that sounded amazing in terms of sound quality but somehow off in terms of soundstage. Suspecting I had somehow mixed up the wires, I checked and re-checked everything, to no avail. I finally decided to test the polarity on each with a 1.5 V battery, and lo and behold, the internal wiring of one of the speakers was switched. I flipped that side and everything came together.
What I am wondering now is if both drivers on the one speaker are suspect. I took a quick look and it seems they are wired correctly, but I am reluctant to start snipping and re-soldering just to be sure. Do you think any out-of-phase effects would be audible at the high frequencies a tweeter produces anyway? I don't mean theoretically, I mean practically - could out-of-phase tweeters be audible?

 

The tweeter polarity could cause significant changes in the response thru the xover region. Not so much between the left and right, but could still be audible.

 

Is there a way to test polarity of the tweeters without actually measuring current across the wires? Like, the battery trick works beautifully with the woofers which visibly respond by moving in or out once DC current is applied, but can you do anything similar with small tweeters? Or is there is an audio test that would be useful? I've tried using the EQ settings to minimize bass and maximize treble and playing some in phase/out of phase tests, but can't hear any difference either way.

 

Do you have a laptop and a microphone? Point the microphone at the tweeter, set up Audacity or similar to record the output of the microphone. Apply the battery test to both speakers in turn, recording the output from both in turn.

Compare the 2 waveforms. If they look similar then you're OK.

 

The battery can test the tweeter polarity, just not thru the crossover which will block the DC. You'd have to bypass the crossover and connect directly to the tweeter to see it move, and you need to keep the voltage low, no more than a 1.5V battery.

More typically, the speakers are tested with a pulse stimulus, and then the output is captured and you can see the relative polarity of the drivers (see one of the many Stereophile magazine speaker tests). You can probably find a signal on youtube, and then setup both speakers next to each other, with microphone equidistant to each tweeter, and pulse one speaker at a time, recording the output, then as @Grower of Mushrooms says, compare the results. If not the same, then maybe one of the speakers is not connected right, but you'd have to decide which one by listening and deciding which one sounds best.

 

You should be able to easily 'hear' if your tweeters are out of phase because your speakers will sound strange. BTDT.

 

Well, I eventually found and played a fairly high frequency test tone that oscillates in and out of phase, and by cranking the treble and killing the bass and standing exactly between the two speakers it did become obvious (and it gave me an instant headache!). It was anything but obvoius trying to listen for the same effect with actual music though. Lower frequencies were obvious even during casual listening though, but the tweeters were tricky.

 

What speakers are these?

Many many speakers speakers have the tweeter inverted compared to the mid or woofer by design.

 

What you’re describing is confusing because you’re using the words “phase” and “polarity” interchangeably. They’re completely different.

A change of polarity is a reversal of the audio connection (e.g., to a pair of speakers). A phase change, by definition, is a shift in time relative to a specific reference. A change in polarity doesn’t affect phase.

 

In designing a 3 way speaker I had to reverse the midrange wiring as compared to the woofer and tweeter which many designers do to make a smoother transition from driver to driver and most importantly to get the imaging correct. I'm sure this could be accounted for in the X-over design but I'm a simpleton when it comes to electronics. When I ran all 3 speakers at the same polarity the center image collapsed. Many X-over 3 way schematics mention that you MUST wire the midrange out of polarity. The tweeters are wired like the woofers.

The soundstage in my OB speaker is huge and more X-over mods should make it even bigger.

 

You are correct. I did use the terms interchangeably in the sense that by flipping the polarity (i.e., flipping the two wires connecting the speaker to the amp) you are effectively shifting the phase. In this regard, is it not correct to assume that connecting both speakers so that + meets + and - meets - generates an identical response where the two speakers are in phase? My understanding is that if two speakers are in phase, they move in tandem and create sound waves that reinforce each other, whereas when they are out of phase, those sound waves cancel each other out. Furthermore, the polarity of the connection (through which an AC current is run) determines if the two electrical inputs match and generate matched responses in the drivers (i.e., in phase).

I found the battery test to be an extremely clear demonstration of this relationship, showing how DC current generates two opposite responses from the driver depending on the polarity of the connection.

 

That’s not correct. Polarity and phase are completely different.

Reversing the polarity of one woofer (for example) causes it to move in the opposite direction of the other one in a stereo system. But both woofers still respond to the musical signal at the exact same time even though the polarity of one speaker is reversed. In other words, they’re still in phase.

If, however, one of the woofer cones (irrespective of its polarity) moved a bit later or a bit earlier than it was supposed to (compared to the other woofer cone) in response to the same musical signal, it would be out of phase. It’s polarity doesn’t cause a timing change, just a change in the direction of physical movement

Again, phase is relative directly to a reference in time. It has nothing to do with the polarity. A speaker does not care which way the electricity travels through it (polarity normal or polarity reversed), and will produce the same music. The strangeness we can hear when one speaker is connected with its polarity reversed is a result of cancellations of certain frequencies in a given music signal.

All you’re describing is what happens when speakers are operating with one connected in normal polarity and the other polarity reversed. Cancellations of certain frequencies are not timing (phase) discrepancies, but rather the physical effect of sound waves at certain frequencies physically interacting to cancel each other out. The phase of the speakers in that situation (in a system - source, amplification, etc. - that is otherwise working properly) is a completely separate matter and has nothing to do with the odd effects you’d be able to hear and measure.

 

OK, but if a system is using AC current to move a driver in and out, depending on the polarity, won't the two different directions of current result in opposite movements of the driver? Put another way, assuming a signal makes the driver move IN - OUT - IN in response to a + / - / + current, won't flipping the wires create the exact opposite result? Now if have two drivers responding to the same AC current, they can either move in unison (if in phase, connected with the same polarity) or in opposition (out of phase, opposite polarity). In this case, woudln't the temporal difference simply due to the staggered response of the two different drivers moving 1/60th of a second apart (assuming 60Hz AC current as we have in Canada)?

 

If polarity is reversed its phase is also reversed 180 degrees.

 

Of course, but they’ll be doing it simultaneously (in opposite directions). No change in phase; only a change in polarity.

At this point, it’s probably advisable for you to do some reading on the subject. The IEEE web site has a ton of instruction on the matter, but it tends to be very dense . So here’s a clear, well-written article on subject from Musician’s Hub:

Tech Tip: Polarity vs. Phase | The HUB

It’s also inadvisable to compare multiphase AC electrical supply (e.g., three-wire/two-phase in 240V systems) because it doesn’t apply to audio systems.

 

OK, so what is actually happening when you flip the wires going into one of two speakers. Why does it sound better one way, worse the other?

 

In response to a given signal being fed simultaneously to both speakers, in one speaker the voice coil is being magnetized to push a woofer cone outward but in the other (reversed polarity) speaker the voice coil is being magnetized the pull the cone inward.

 

And isn't that referred to as being out of phase?

 

Are you arguing in favor of the common mistake that is made (using polarity and phase interchangeably), or are you trying to make the case that phase is an effect of polarity in Audioland? If it’s the former, I think you’ll be well served by doing the basic reading on the subject for clarification. If it’s the latter, you’re incorrect.

 

ag, the woofers will be out of phase if one is reversed wired. one cone will push as he other cone is retracting to the same note.
polarity and phase are completely different but polarity does affect phase.

 

OP,

reversing polarity on one tweeter will cause the imaging to shift radically. reversing polarity on both tweeters will generally cause a midrange suckout and the sound will be veiled muffled.
reverse polarity on one woofer will cause a lack of bass.
to test polarity of the woofers play some bass heavy music and reverse one set of speaker lead wires. more bass- you have a wiring problem with the woofers. less bass- woofers are wired correctly.

to check the polarity of the system, play a spoken word recording. when both tweeters are wired correctly with their respective midrange, the sound will be clear and solidly centered.

 

That's exactly what I did - first checked the woofers, and discovered one was reversed at the driver. Then I checked the tweeters with a test tone and a vocal test track and they seem fine.
Problem solved.
I appreciate the difference between polarity and phase, but the former does influence the latter, and that was my only point. It is also commonly (and not technically correctly) said that speakers wired with opposite polarity play are out of phase, and that's all I meant.

 

Out of phase, in your example, would mean that each woofer was moving at a different time relative to the input signal. That doesn’t happen when polarity of one connection is reversed. Rather, the woofers move at the same time relative to the input signal but in different directions.

In audio, the words “polarity” and “phase” are not interchangeable. Differences in polarity occur without a change in phase. Phase differences between two speakers can occur when polarity of each connection is the same. The fact that people sometimes think of polarity and phase as two sides of the same coin is a misconception. Phase is a time reference; polarity is not. Polarity is an electromagnetic phenomenon; phase is not, though it can be influenced by reactive differences of or between a pair of speakers handling the timing of an electromagnetic signal.

Here’s another explanatory link, this one from Galen Carol Audio:

PHASE VS. POLARITY | Galen Carol Audio | Galen Carol Audio

 

. . . and that’s not accurate. Polarity and phase changes occur simultaneously sometimes, but they’re different phenomena. When polarity is reversed on one speaker, it is out-of-polarity not out-of-phase. Perhaps this different, well-written explanation from Galen Carol Audio will help (if the previous link from Musician’s Hub was unclear):

PHASE VS. POLARITY | Galen Carol Audio | Galen Carol Audio

 

I use the terms "polarity" and "absolute phase" somewhat interchangeably. It's obvious what each means in context.
The context of what the OP is doing makes it obvious that he means "absolute phase" when he says "phase".

Absolute Phase: Fact or Fallacy?
Absolute Phase