Maybe I should remove them..
Yes I know it cannot be true. It just does not matter.
'Phase' is of course a frequency & wavelength dependent quantity. See eg
AES E-Library >> Is Linear Phase Worthwhile?
I am suitably reprimanded
I'll rephrase the question.
Is the Polarity of your Left channel speaker different from the Polarity of your Right channel speaker below 130Hz?
This only requires knowledge of how you have connected the wires to your subs & mains and the polarity of the amps. I'll ignore the phase behaviour of the xovers as its detailed in the above paper.
You'll excuse me if I ignore the noise, (religous, pedantic and/or often false ....
Just after simple FACTs that you probably have at your fingertips and cost you nothing to supply .. like how have you connected your speakers. Asking for more than that seems particularly unproductive.
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OK, I'll stop suggesting you don't know what you are talking about and instead explain....Is the Polarity of your Left channel speaker different from the Polarity of your Right channel speaker below 130Hz?
This only requires knowledge of how you have connected the wires to your subs & mains and the polarity of the amps. I'll ignore the phase behaviour of the xovers as its detailed in the above paper....
Just after simple FACTs that you probably have at your fingertips and cost you nothing to supply .. like how have you connected your speakers. Asking for more than that seems particularly unproductive.
First of all, anybody can see that I've posted pairs of FRs. Tell me, kgrlee, which do you suppose is the same-polarity pair and which the funny one? Or maybe you are worrying that the amps are reversed and so are the wires? Or maybe I mounted the sub driver with the magnet sticking out? Or..... In other words, I have no idea how the drivers are manufactured (conventionally, I hope) but I (and you, I hope) can tell perfectly well how they are acting from the obvious paired comparison.
Next, you ask about the wires connecting to the speaker terminals from bi-amped amps. Of course the signals are for all practical purposes of the crude demo identical. Duh. What is the exercise all about?
Next and using round numbers to explain it easier, we are talking about sound waves traveling to the mic over a distance of say 140 inches from one driver and 144 to the other driver even when the boxes are nominally in equidistant corners and the mic was just plunked down at an accidental spot on (roughly) the midline. It would make no practical difference if my elderly eyeballs missed the room midline by a few inches at these frequencies.
At 80 Hz (about 14 inches wavelength) one wave has traveled 10.0 times 360 degrees and the other 10.3. At different frequencies, it would obviously be a different discrepancy. So to answer you question with these figures, the phase angles were 3600 degrees and 3703 degrees, corrected of course, by the speakers' contribution to phase at different frequencies and which is unknown.
Wrapping up, your question is meaningless and shows lack of understanding of acoustic waves and phases. The mic test shows what it shows and all the rest is quibbling about trivial details.
My purpose was to illustrate that even a drastic phase adjustment like polarity reversal in real rooms does not result in the textbook wave arithmetic. Not an odd idea but you'd have trouble finding it illustrated anywhere for a real room. I believe I've made my entirely uncontroversial point and would like to leave it at that.
Thanks.
B.
B.
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Let's start with the first claim: the wavelength of an 80 Hz signal is 4.3 meters (~ 169 inches, or 14 feet). So, maybe you should stop lecturing people about their lack of understanding when it comes to acoustic waves.
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It would be important or not that in addition to the shape and dimensions of the hearing room, mention should also be made of the existence of "resonance chambers" in the same (placards), and if they are partially or fully enabled (closed or open doors Are they folding or sliding?
I mention this because I believe that everything influences the measurements ....
I mention this because I believe that everything influences the measurements ....
Thanks for all the clarification Ben. I have pored over your pic in #46 in the light of these new explanations and am now certain that I have extracted all the data that my small brain can possibly use. I shall not ask for more.
What I was trying to establish was if you system uses 2 subwoofers 'IN PHASE', or more correctly 'WITH THE SAME POLARITY', below 130Hz.
In your original post, you show response curves and suggest the 'OUT OF PHASE', or more correctly 'WITH DIFFERENT POLARITY', version is preferable.
What is not clear is if your usual system has these 'DIFFERENT POLARITY' subs below 130Hz.
May I suggest you re-visit your textbooks. You might start with the chapter on the speed of sound. I have crossed swords with various acousticians in the past on this subject but even I haven't the nerve to suggest variations as large as you show.
Of course, you might be on a different planet ... where your wavelengths might be entirely appropriate.
Thanks for this Ben.
I see that your actually listening position has the subs with 'SIMILAR POLARITY' with some added 'PHASE tweaking'. The curves in your original post were at some position you are reluctant to specify. This allows us to put the correct significance and importance to your posts in this thread.
Incidentally, you say a lot about "textbooks" and "phase annihilation diagram for woofer frequencies", ".. results of bouncing off the walls and the irregular distances and phase irregularities that have an impact on the bass in a dipole...", ".. rear sound bounces around and the phases get messed up a lot".
Which textbooks say these things or similar?
I have a small collection of textbooks which I use mainly for toilet paper as i kunt reed en rite. But none of them say anything of the sort.
I don't think even the tomes written for the unwashed masses claim anything like this. In fact, your claims are the first I've seen of this kind.
Incidentally, AES E-Library >> Is Linear Phase Worthwhile? explains just that though many speaker designers are often unaware of exactly what they are doing.
The most common high quality treble crossover is the Arthur-Smyth third order (AS3) which I helped Robert Arthur-Smyth to formalise at Celestion.
Among other things, it incorporates your 'Phase Tweaking' though the technique was old by the late 70s for passive crossovers.
I just pretended to do the maths to tell the speaker designers what they were actually doing.
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