Polarity mystery: Can you help me solve it?

Bryoncunningham,

I was not saying the two box speakers were out of phase with each other, they are not. I was saying the two drivers housed inside each box speaker are wired out of phase with respect to one another. Am I still wrong.

By chance have you listened to the Focal 1007be speakers, wired both ways, with the JL Audio Fathom F113 sub turned off?

No doubt you and Al are a hell of a lot smarter on this subject than I am.

I was saying the two drivers housed inside each box speaker are wired out of phase with respect to one another.

Yes, that's correct, Jim. That is done intentionally in some speaker designs, and as I said in my previous post I believe it is necessary in those cases to achieve flat frequency response.

By chance have you listened to the Focal 1007be speakers, wired both ways, with the JL Audio Fathom F113 sub turned off?

Excellent question. Obviously inverting the connection polarity to the main speakers changes the phasing of mains vs. sub by 180 degrees. Presumably that would only affect frequencies for which the sub produces significant output, which presumably don't play a major role in imaging, but considering that we can't come up with any other explanations that hold water the experiment you suggest seems well worth trying.

Best regards,
-- Al

If you want to get a better idea what's going on, then at some point, after getting completely used to the way things are now . . . you need to put the connections back the way they were originally, and leave it that way long enough to form some new impressions all over again. The perceived change in sound should then of course be the opposite of what you first experienced. This is an important step - it will help rule out side-effects from the dismantling (i.e. tightening up the speaker drivers, refreshing connections), as well as confirm again that you're hearing what you think you're hearing.

But assuming that the sonic effects reverse as predicted . . . I didn't read that you reversed the speaker cables themselves at the same time? While I don't think that the absolute phase of small loudspeakers such as yours will make much difference per se, keep in mind that if you invert absolute phase at the speaker, you're changing the left/right speakers' relative phase in relation to the subwoofer, which I would expect to be audible. So it's important to establish the effects of simply reversing the phase of (both) your main speakers, independently of reversing the phase of the individual driver connections.

Okay, so assuming that you're noticing a difference in the sound when you reverse the individual driver leads, but also reverse the speaker cables themselves (to preserve absolute phase) . . . then the most likely explanation is that the loudspeakers' drivers/cabinet and crossover interact with each other differently when the phase is inverted . . .

. . . and a couple of things come to mind here. First, this speaker uses a 36dB/octave 2-way network? That means a minimum of six capacitors and six inductors, and that's quite a bit to fit into that small cabinet . . . so some of the inductors are probably metal-core, and maybe one or two of the caps is an electrolytic? So it's possible that the bass portion of the crossover has a significant nonlinear transfer function, and the woofer/cabinet together definately have a nonlinear transfer function. So when you invert the phase between the drivers and crossover, you will be altering how these two transfer functions combine with each other, which may have some subtle effects on the transition-band behavior.

But finally (moving on to my favorite theoretical speculation), even assuming the crossovers' components themseves are pretty much ideal, all the inductors are going to be in fairly physically close each other, and to the woofer motor structure as well. I can also confirm from experience that subtle changes in the orientation and layout of crossover inductors can measurably affect the response of the crossover, and the woofer motor can produce a significant alternating magnetic field as a result of its modulation. So I'm guessing that in your case, where you have strong speaker magnets and a complex crossover, all stuck together in a small loudspeaker, that by reversing the driver lead phasing you're changing the electromagnetic interaction between all of thse components.

Both the woofer and tweeter are connected through a crossover which causes phase shift as a function of frequency (and order of the crossover). At the crossover frequency both drivers are equally loud. You want them to be in phase at this frequency or else they will counteract each other. If the phase difference is 180 degrees you will need to connect the two drivers with oposite polarity. If the phase difference is something other than 180 degrees neither wiring polarity is perfect. Try it both ways and pick what sounds or measures best.

Relative position of the two drivers also affects the acoustic phase. It is easy to tell when driver polarity is wrong: there will be a deep notch at the crossover frequency

If you were to reverse the speaker connections, that ENTIRE waveform (including the initially negative-going tweeter output and the initially positive-going woofer output) would be inverted.

Ahhh! Now I get it, Al. The sentence above is what made it click for me. And yes, that does clarify your befuddlement, and it intensifies mine!

I was not saying the two box speakers were out of phase with each other, they are not. I was saying the two drivers housed inside each box speaker are wired out of phase with respect to one another.

Jea48 - Sorry, I misunderstood you. You are correct - the tweeter and the woofer, in each speaker, are wired with opposite polarity. This is common practice with a Linkwitz-Riley crossover with a 36 dB slope, as described here. As Al pointed out in his last post, the inversion is necessary to provide a flat frequency response.

By chance have you listened to the Focal 1007be speakers, wired both ways, with the JL Audio Fathom F113 sub turned off?

Yes, I have. The results are the same. So I don't believe the sub is a factor. And the sub polarity is the same as the woofers on the mains (both negative). I switched the sub polarity at the same time I switched the speaker cable leads to the mains, changing them both from positive to negative. Now that the woofers on the mains are negative polarity, failing to change the sub to negative polarity results, as you would expect, in a significant diminishment of bass due to cancellation. But I have not been listening to it that way, so that is also not a factor.

If you want to get a better idea what's going on, then at some point, after getting completely used to the way things are now . . . you need to put the connections back the way they were originally, and leave it that way long enough to form some new impressions all over again. The perceived change in sound should then of course be the opposite of what you first experienced. This is an important step - it will help rule out side-effects from the dismantling (i.e. tightening up the speaker drivers, refreshing connections), as well as confirm again that you're hearing what you think you're hearing.

This is a good suggestion, Kirkus.

...then the most likely explanation is that the loudspeakers' drivers/cabinet and crossover interact with each other differently when the phase is inverted...

This was my original theory. But I thought that Al just explained how any improvement due to driver/crossover/cabinet interaction would only apply to recordings with a particular absolute polarity, positive or negative. But the improvements I've experienced seem to be constant regardless of the absolute polarity of the recording. Does that refute the driver/crossover/cabinet interaction theory? Now I'm confused again!

So I'm guessing that in your case, where you have strong speaker magnets and a complex crossover, all stuck together in a small loudspeaker, that by reversing the driver lead phasing you're changing the electromagnetic interaction between all of thse components.

Fascinating. But would this effect be constant across all recordings with different absolute polarities?