Polarity mystery: Can you help me solve it?

Jea48 - No, the two speakers are in phase with each other. And no, the woofer does not produce less bass. I believe you are confusing the following:

(1) The ABSOLUTE polarity of a recording - positive or negative.
(2) The RELATIVE polarity of a component - preserving or inverting.
(3) The RELATIVE polarity of the system - preserving or inverting.

Re: (1) The ABSOLUTE polarity of a recording refers to whether or not the waveforms represented in the recording correspond to the waveforms of the sound waves created by the real musical event. In recordings with POSITIVE absolute polarity, a COMPRESSION wave at the microphone corresponds to a COMPRESSION wave represented on the recording, while a RAREFACTION wave at the microphone corresponds to a RAREFACTION wave represented on the recording. In recordings with NEGATIVE absolute polarity, a COMPRESSION wave at the microphone corresponds to a RAREFACTION wave represented on the recording, and a RAREFACTION wave at the microphone corresponds to a COMPRESSION wave represented on the recording.

Re: (2). The RELATIVE polarity of a COMPONENT refers to whether the component preserves or inverts the polarity that it receives at its input. By reversing the speaker cable leads to my speaker terminals, I have changed the RELATIVE polarity of the speakers, that is to say, RELATIVE TO THE SIGNAL BEING SENT FROM THE AMPLIFIER. But because I reversed the leads to BOTH speakers, they are still in phase RELATIVE TO EACH OTHER. That is why I did not experience a diminishment of bass due to cancellation.

Re: (3) The RELATIVE polarity of a SYSTEM refers to whether the playback system, taken as a whole, preserves or inverts the polarity of the recording. A POLARITY-PRESERVING system will preserve the absolute polarity of recordings. A POLARITY-INVERTING system will invert the absolute polarity of recordings. When you put this together with (1), i.e., the fact that some recordings have POSITIVE absolute polarity and some have NEGATIVE absolute polarity, you get the following result: A POLARITY-PRESERVING playback system will preserve the "polarity" of the original event (i.e. compression=compression/rarefaction=rarefaction) ONLY WHEN the absolute polarity of the recording is POSITIVE. A POLARITY-INVERTING system will preserve the "polarity" of the original event ONLY WHEN the absolute polarity of the recording is NEGATIVE.

Al will correct me if I got any of this wrong.

Apologies if I'm telling you things you already know.

Hi Bryon,

I agree completely with everything in your preceding post.

Assuming that the improvement I experienced really is constant across all recordings, regardless of their polarity, then surely we are right to conclude, as you and I both have, that the ABSOLUTE polarity of the recordings is irrelevant to the issue. But does it follow from that, that the RELATIVE polarity of the tweeter/woofer is irrelevant to the issue? I'm getting a little lost in the how that inference works.

BTW, I don't know if it's relevant, but the two drivers are not on the same plane. The woofer is recessed in the speaker cabinet, so that its center is slightly farther from the listener than the tweeter.

While the polarity inversion of the tweeter relative to the woofer is certainly relevant to the sound of the system (and I believe, although I'm not totally certain, that the inversion is necessary to flatten the frequency response of the speaker given the particular crossover design), the bottom line is simply that two inversions in the signal path (prior to the speaker) and/or in the recording = no inversions, regardless of how the tweeter and woofer are phased relative to each other.

Let's say that the speaker connections are reversed, and that a polarity-correct recording is being played, and that imaging is improved for that recording relative to what it was with the speaker connections not reversed. In that situation the tweeter's output will be polarity correct relative to the original event, and the woofer's output will be inverted relative to the original event.

If we now play a recording that has inverted polarity, with the speaker connections still reversed, the tweeter's output will be inverted relative to the original event, while the woofer's output will be polarity correct relative to the original event. Which is the same situation that we had with the previous recording when the speaker connections were not reversed, which resulted in inferior sound on that recording.

So the fact that reversing speaker connections provides improvement that is consistent regardless of the polarity of the recording is what is so baffling.

Another way to look at it is to consider Figure 7 of John Atkinson's measurements, linked to in earlier posts. That depicts the speaker's response to a positive-going pulse or step waveform, which by definition (or, more precisely, by Fourier theory) includes sinusoidal spectral components at both low frequencies and high frequencies. The initial response to the application of that waveform is a negative-going half-sine wave, since the (inverting) tweeter responds to the signal's high frequency content sooner than the woofer can begin to respond to lower frequencies (and also because the path length from listener to tweeter is slightly less than the path length from listener to woofer, as you noted). The response to that high frequency spectral component eventually oscillates to a positive-going half cycle, at which time the output of the woofer starts to predominate, beginning with a low frequency positive-going half-sine wave, and eventually oscillating to be negative-going.

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. If the polarity of the recording were then inverted, that ENTIRE waveform would then be re-inverted back to what it was for a non-inverted recording with non-inverted speaker connections.

I hope that further clarifies my befuddlement :)

Best regards,
-- Al

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.