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Post by sahmen on Jul 30, 2019 3:03:22 GMT -5
Lol : This is me trying to figure out whether my speakers are in-phase or out of phase, after reading all the posts on this thread : Translation: I confess to being totally dazzled and 100% befuddled, although, I'm still intrigued because I would like to learn (I must be a masochist, as my mother--bless her soul--used to say sometimes )
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Post by pedrocols on Jul 30, 2019 8:13:27 GMT -5
Didn't we agree to limit engineers'comments to just 50 words per post?🤔😂
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DYohn
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Post by DYohn on Jul 30, 2019 8:51:40 GMT -5
Want to know if you speakers are in phase without a bunch of test equipment? Play a test tone on one speaker by itself. Note the loudness level (by ear, with a meter, with an audio app on a cell phone, doesn't matter.) Now without changing the volume connect speaker number 2. Did it get slightly louder from the same listening position? If yes you are in phase. If no, you aren't.
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Post by brutiarti on Jul 30, 2019 9:16:22 GMT -5
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KeithL
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Post by KeithL on Jul 30, 2019 9:51:20 GMT -5
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ...
—To my knowledge, ALL Emotiva amps of any generation have the XLR inputs wired with Pin #3 hot. —To my knowledge all Emotiva preamps and processors have their XLR outputs wired Pin #2 hot. —To my knowledge not stated by Emotiva (hearsay is that) all Emotiva Preamp/Processor inputs are Pin #2 hot. I here ask KeithL or Lonnie to verify these statements. Thanks Audio....my gut feel is the same just want certainty. lonnie , keith 1. Can you please confirm the above from AudioHTIT re which pins are hot on each product category? 2. Keith you have already confirmed the input to output circuitry on the Emotiva amplifiers retain absolute phase ie no flipping internally. How about the processors and the preamps?These are not questions to solicit theoretical answers but simple technical question on how the Emotiva gear works (yes, no, confirmed etc). As for the debate around absolute or relative or or or other phasing we can work that out post understanding how the gear works. I don't really care what standard Emotiva used (thats your call and I still bought the gear ) as long as I know how to treat it in the real world when I connect it to other gear and speakers. Thanks
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Post by lrobertson on Jul 30, 2019 9:57:11 GMT -5
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ...
Thanks Audio....my gut feel is the same just want certainty. lonnie , keith 1. Can you please confirm the above from AudioHTIT re which pins are hot on each product category? 2. Keith you have already confirmed the input to output circuitry on the Emotiva amplifiers retain absolute phase ie no flipping internally. How about the processors and the preamps?These are not questions to solicit theoretical answers but simple technical question on how the Emotiva gear works (yes, no, confirmed etc). As for the debate around absolute or relative or or or other phasing we can work that out post understanding how the gear works. I don't really care what standard Emotiva used (thats your call and I still bought the gear ) as long as I know how to treat it in the real world when I connect it to other gear and speakers. Thanks Thanks for all your time on the subject Keith. Can I quickly ask if the sherbourn amps are the same design in this regard to the Emotiva amps?
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KeithL
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Post by KeithL on Jul 30, 2019 10:21:57 GMT -5
The short answer - for now - is that I don't have that specific information on the Sherbourn amps handy. I think that all or most of those are probably Pin 2 (+).
I don't have time to go digging around in old schematics right now.... Try me again after the next few product releases and I'll see what I can find.... (Or just listen, and flip them, if you can hear any difference.)
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ... Thanks for all your time on the subject Keith. Can I quickly ask if the sherbourn amps are the same design in this regard to the Emotiva amps?
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geebo
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"Too bad that all the people who know how to run the country are driving taxicabs and cutting hair"
Posts: 24,188
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Post by geebo on Jul 30, 2019 10:36:31 GMT -5
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ... Thanks Audio....my gut feel is the same just want certainty. lonnie , keith 1. Can you please confirm the above from AudioHTIT re which pins are hot on each product category? 2. Keith you have already confirmed the input to output circuitry on the Emotiva amplifiers retain absolute phase ie no flipping internally. How about the processors and the preamps?These are not questions to solicit theoretical answers but simple technical question on how the Emotiva gear works (yes, no, confirmed etc). As for the debate around absolute or relative or or or other phasing we can work that out post understanding how the gear works. I don't really care what standard Emotiva used (thats your call and I still bought the gear ) as long as I know how to treat it in the real world when I connect it to other gear and speakers. Thanks So does Dirac correct for speaker phase?
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Post by hsamwel on Jul 30, 2019 11:09:28 GMT -5
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ...
Thanks Audio....my gut feel is the same just want certainty. lonnie , keith 1. Can you please confirm the above from AudioHTIT re which pins are hot on each product category? 2. Keith you have already confirmed the input to output circuitry on the Emotiva amplifiers retain absolute phase ie no flipping internally. How about the processors and the preamps?These are not questions to solicit theoretical answers but simple technical question on how the Emotiva gear works (yes, no, confirmed etc). As for the debate around absolute or relative or or or other phasing we can work that out post understanding how the gear works. I don't really care what standard Emotiva used (thats your call and I still bought the gear ) as long as I know how to treat it in the real world when I connect it to other gear and speakers. Thanks Sorry for asking, but you didn’t mention balanced input of your processors, specifically RMC-1. I guess +2 pin? I also guess all other equipment (XSP, ERC etc.) inputs and outputs other than amps inputs have +2 pin? The good thing about connecting absolute phase is peace of mind, knowing that everything is connected as it should.
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Post by AudioHTIT on Jul 30, 2019 11:37:54 GMT -5
Thanks Audio....my gut feel is the same just want certainty. lonnie, keith 1. Can you please confirm the above from AudioHTIT re which pins are hot on each product category? 2. Keith you have already confirmed the input to output circuitry on the Emotiva amplifiers retain absolute phase ie no flipping internally. How about the processors and the preamps?These are not questions to solicit theoretical answers but simple technical question on how the Emotiva gear works (yes, no, confirmed etc). As for the debate around absolute or relative or or or other phasing we can work that out post understanding how the gear works. I don't really care what standard Emotiva used (thats your call and I still bought the gear ) as long as I know how to treat it in the real world when I connect it to other gear and speakers. Thanks Sorry for asking, but you didn’t mention balanced input of your processors, specifically RMC-1. I guess +2 pin? I also guess all other equipment (XSP, ERC etc.) inputs and outputs other than amps inputs have +2 pin? The good thing about connecting absolute phase is peace of mind, knowing that everything is connected as it should. I updated my post on the previous page with this confirmation, and will update again when we get this final piece on the preamp/processor inputs. Thanks for the update Keith.
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Post by donh50 on Jul 30, 2019 13:17:57 GMT -5
So does Dirac correct for speaker phase? Yes. Take note: less than 50 words.
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Post by AudioHTIT on Jul 30, 2019 13:30:44 GMT -5
So does Dirac correct for speaker phase? Yes. Take note: less than 50 words. Wait, I need more explanation! So we know it will do phase in the sense of time and distance, but you’re saying it will correct for a speaker 180 out of phase? I’ve heard people saying that Dirac reported their speakers ‘out of phase’, but didn’t know if it corrected them too?
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DYohn
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Posts: 18,348
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Post by DYohn on Jul 30, 2019 13:38:01 GMT -5
Time + Distance + SPL = phase in the acoustic sphere.
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Post by donh50 on Jul 30, 2019 14:04:36 GMT -5
Yes. Take note: less than 50 words. Wait, I need more explanation! So we know it will do phase in the sense of time and distance, but you’re saying it will correct for a speaker 180 out of phase? I’ve heard people saying that Dirac reported their speakers ‘out of phase’, but didn’t know if it corrected them too? Yes. As will most room correction programs. It has been a long time since I asked for any details so I do not know exactly how DL does it, but most of them will do a simple (digital) polarity inversion if they sense a 180 deg phase shift, then apply their filters to correct the frequency response. You may have noticed that, even when you get an "out of phase" warning, the manual says to just carry on if the speakers are wired correctly and they all go on to correct the response anyway. Disclaimer: hand waving follows, and I am going to far exceed my 50-word limit even at that. Purists will cringe at some of the terminology and simplified explanations, but then again if they know it already don't need to read this post. Phase at a given frequency is another way of expressing a time displacement (shift, change). Room correction programs that include some sort of time-domain analysis (Dirac Live, Audyssey, MCACC etc.) will adjust the phase over frequency to align the signal at the MLP. It is more than just a time delay (group delay is the derivative of phase over frequency, I'll stop there with the math). Bottom line is, if they adjust the phase over frequency, it is equivalent to adjusting the time delay over frequency. More or less. Why not just distance? At 100 Hz a wavelength is about 1127 ft/s / 100 Hz = 11.27 ft. So a 180 degree phase shift is about 5.6'. At 1 kHz, the wavelength is 1.127 ft (13.5", so 0.56' or 6.8" will effectively invert the polarity), and at 10 kHz the wavelength is just 0.1127 ft (1.4") and 180 degrees is about 0.7". The phase shift measured very much depends upon where you sit and the frequency of the signal, and that is before crossovers and such in the processor and speaker change it completely. If the speaker has linear phase, then the group delay is constant, which is a fancy way of saying the speaker is time-aligned and you can move it back and forth without worry. Most speakers are not, and most crossovers also add phase shift. It's complicated. But room correction works well, and even doing it manually generally provides acceptable results (though measurements help). We are pretty tolerant and tend to listen through fairly glaring errors. HTH - Don
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KeithL
Administrator
Posts: 9,941
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Post by KeithL on Jul 30, 2019 15:20:58 GMT -5
OK.... On the XSP-1 and all the processors.... the Balanced INPUTS are also Pin 2 (+)
OK ..... absolute phase ..... once and for all .....
On the balanced outputs ..... On the XSP-1, the XMC-1, the XMC-2, the RMC-1, and the RMC-1L .....
Pin 2 is (+)
On ALL of our amps that have XLR inputs ....
Pin 3 is (+)
(There were good engineering reasons for this choice originally; and we have continued it so all of our amps are consistent.)
And, if you're really concerned about absolute phase, and convinced you can hear a difference ... Then you can reverse the absolute phase by ... - EITHER finding or building interconnects that swap Pin 2 and Pin 3 ... - OR swapping the red and black on your speaker connections ... Sorry for asking, but you didn’t mention balanced input of your processors, specifically RMC-1. I guess +2 pin? I also guess all other equipment (XSP, ERC etc.) inputs and outputs other than amps inputs have +2 pin? The good thing about connecting absolute phase is peace of mind, knowing that everything is connected as it should.
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Post by jim80z on Jul 31, 2019 7:13:46 GMT -5
OK.... On the XSP-1 and all the processors.... the Balanced INPUTS are also Pin 2 (+)
Sorry for asking, but you didn’t mention balanced input of your processors, specifically RMC-1. I guess +2 pin? I also guess all other equipment (XSP, ERC etc.) inputs and outputs other than amps inputs have +2 pin? The good thing about connecting absolute phase is peace of mind, knowing that everything is connected as it should. Thanks Keith, perfect!
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Post by AudioHTIT on Aug 1, 2019 0:04:03 GMT -5
While looking through the JBL thread, I was reminded of another component of phase that may need to be considered in some systems.
We’ve generally discussed hooking our speakers to our amps ‘normally’, that is, red to red and black to black; or ‘reversed’, red to black and black to red, but that assumes we know what’s normal or that there’s a standard.
For some time, most speaker manufacturers have built speakers with what’s called ‘positive phase’, which is defined that when a positive voltage is applied to the ‘red’ terminal the cone moves out or forward. These days we assume all manufactures build speakers with positive phase, but this wasn’t always the case.
Early in their history JBL chose (somewhat arbitrarily) to build their speakers with negative phase, that is, when a positive voltage is applied to the red terminal, the speaker cone moves in or back. I happen to have two rather old guitar speakers (JBL D-131) that were built to this negative phase standard.
So how does this fit into our scenarios above? Well, in my case I use my D-131’s with a stereo amp, and they are wired the same, so everything’s in phase, no problemo. What if however I decided to replace the L/R B&W’s in my HT system with these two JBLs (not likely, but play along), what would happen then? Well, we now know that if I hooked everything up normally, red to red and black to black, that my L/R speakers would be out of phase with the other speakers in my 7.2 system.
It’s not that far fetched that someone could build a surround system with a combination of legacy JBLs and newer models, they would have to account for this mix in phases.
What if weren’t sure how a specific speaker is phased (or we just like to experiment)? Well many know if you’re trying to troubleshoot speakers and their connections, you can connect a 1.5V battery across the wires (it works best if you hold one end on, and tap the other end). This causes the speaker to make a popping sound. But if the woofer cone is visible, you can watch to see whether the cone goes in or out, and which wire is connected to the positive battery pole will tell you if the speaker is positive or negative phase.
So, most speakers today are built positive phase, but it wasn’t always so, and if you’re not sure it’s easy to check.
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Post by markc on Aug 1, 2019 3:11:20 GMT -5
Yes. Take note: less than 50 words. Wait, I need more explanation! So we know it will do phase in the sense of time and distance, but you’re saying it will correct for a speaker 180 out of phase? I’ve heard people saying that Dirac reported their speakers ‘out of phase’, but didn’t know if it corrected them too? Alert: More than 50 words but my disclaimer is that I am not an engineer! As you point out, phase is about time and distance and when those overlapping sine waves hit your ears. With the much shorter wavelengths of low frequency bass, this is even more relevant to subwoofers. Subwoofer phase is exactly about time and distance and not just to do with polarity of wiring. The issue is the processing time of the subwoofer. A pre-amp/surround processor outputs sound to the main speakers (via a power-amp) in real time - there is no delay in this signal chain after the SSP other than the speed of electricity down a wire which is negligible in contrast to the speed of sound and can be ignored. We compensate for distance of speaker from the MLP using relative delays in the processor, by entering speaker distances from MLP. The signals are simultaneously sent to the subwoofer. However, most subwoofers have an internal delay due to the processing circuitry which is in the order of 10-25 milliseconds depending on your sub. This means the bass produced by the sub is not in exact sync with the bass from the main speakers - it is delayed by 10-25ms! To compensate for this, the sub phase setting lets you partially (and only crudely) correct for this so that a sine wave peak from both sub and mains will coincide at the MLP for maximal bass response, rather than arrive out of phase and have partial cancellation. This is why most subwoofers have a phase selector - either 0-180 or like mine, 0-90-180-270 for more (but still crude) realignment.However - the sub phase setting is simply functioning by introducing a further delay, so that the sine waves of the bass sounds from both sub and mains are more likely to be aligned at the MLP. Sub processing time cannot be shortened. Critical note: the bass peaks are only in phase when you do this - it is not in sync! The bass produced by the sub is reaching the MLP after the bass from the mains and may be noticeable on the attack and fade. The accepted best way to correct for this is to incrementally INCREASE the distance setting of the subwoofer from the MLP within the Surround Sound Processor beyond what the ACTUAL distance is - This would usually need to be between 3-8 metres (10-25 feet) to compensate for the 10-25ms subwoofer internal processing delay until the bass response is audibly optimal. (Remember that this matches with what Dan pointed out that sound travels at approx. 1 foot per millisecond) (Dirac Live is doing this automatically we would hope, using its impulse response measurements, and certainly, it is not possible to set or change Speaker Distances in the Dirac Live speaker preset in the XMC-1: "distance" (=relative delay) is set automatically after Dirac's measurements) The reason for INCREASING sub distance in the processor is that it means that the processor will DELAY the audio to the main channels so that their sound reaches the MLP at the same time as the "further away" subwoofer sound. The sub is delaying the audio that it produces, so we are forcing the processor to delay the audio to the mains (because we cannot make the sub speed up it's processing and nor can the SSP send audio to the subwoofer early) (Decreasing the distance of all of the other speakers would also work exactly the same, but is more fiddly. One could do it if the SSP runs out of Distance adjustment for the subwoofer) Delaying audio is not a problem and fits in well with home theatre AV sync because the system almost always has to introduce an audio delay anyway because of video processing time by the display. Finally - inflating subwoofer distance setting in the SSP and causing mains (LCR and surrounds) audio delay is waaaaay more accurate than using the subwoofer phase switch whether 0-180 or 0-90-180-270. At 80Hz, sound has a wavelength of 4.3m (14 feet), so even a 0-90-180-270 phase setting is only making changes (delays) in steps of 1.1m (3'6") Distance settings in the SSP are 10cm increments so 11x finer so you are MUCH more likely to get the sine waves to coincide and they will also be in sync and not just in phase! Best advice - leave subwoofer phase setting on 0, and increase sub distance in the SSP beyond what the distance actually is.
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Post by pedrocols on Aug 1, 2019 8:18:39 GMT -5
Variable phase control knobs on subwoofers are so very helpful.
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KeithL
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Post by KeithL on Aug 1, 2019 10:26:11 GMT -5
All quite true.... However, add to all the the fact that virtually all speakers exhibit a phase shift that changes with frequency. (For some, that phase shift may vary by as much as 720 degrees over the range from 20 hz to 20 kHz.) [[ I should add that this is different for each speaker model... and there is no standard... and no reason to assume that it will be similar between different speaker models ]]
(Testing with a battery only shows you the "physical electrical phase" for DC.... which is likely to match the electrical phase, more or less, at low frequencies.)
Most "well behaved speakers" exhibit a phase characteristic that varies smoothly as the frequency goes up... (so the phase plot is a smooth curve that covers about 720 degrees). However, some speakers are designed to minimize the overall phase shift, and do so by adding various delays, or by connecting some drivers in reversed phase. The phase plots on some of these may exhibit a zig-zag pattern of some sort. (You sometimes also see what looks like this if a speaker with a large but smoothly varying phase shift is plotted on a graph that "wraps around" at 360 degrees.) In general, smoothly varying this tends not to be very audible, depending on who you ask, but it could become critical if you were mixing different brands or models of speakers. For example, if you have two very different speakers, they could be exactly in phase at 50 Hz, but exactly out of phase at 2 kHz.... This could lead to very odd sound stage imaging between them (and is one reason why it's pretty critical to match both speakers in each symmetrical pair).
In that case, unless you have software that can make significant complex phase corrections, you're simply not going to get them to be in phase across the entire audio band. Your best bet would probably be to get them to be in-phase in the midrange voice region - where our human hearing is most sensitive to such things.
It would be better to use all speakers that are at least similar - same manufacturer and, better yet, same model line.
(For example, all of our current Airmotiv models are pretty well matched.)
While looking through the JBL thread, I was reminded of another component of phase that may need to be considered in some systems. We’ve generally discussed hooking our speakers to our amps ‘normally’, that is, red to red and black to black; or ‘reversed’, red to black and black to red, but that assumes we know what’s normal or that there’s a standard. For some time, most speaker manufacturers have built speakers with what’s called ‘positive phase’, which is defined that when a positive voltage is applied to the ‘red’ terminal the cone moves out or forward. These days we assume all manufactures build speakers with positive phase, but this wasn’t always the case. Early in their history JBL chose (somewhat arbitrarily) to build their speakers with negative phase, that is, when a positive voltage is applied to the red terminal, the speaker cone moves in or back. I happen to have two rather old guitar speakers (JBL D-131) that were built to this negative phase standard. So how does this fit into our scenarios above? Well, in my case I use my D-131’s with a stereo amp, and they are wired the same, so everything’s in phase, no problemo. What if however I decided to replace the L/R B&W’s in my HT system with these two JBLs (not likely, but play along), what would happen then? Well, we now know that if I hooked everything up normally, red to red and black to black, that my L/R speakers would be out of phase with the other speakers in my 7.2 system. It’s not that far fetched that someone could build a surround system with a combination of legacy JBLs and newer models, they would have to account for this mix in phases. What if we’re not sure how a specific speaker is phased (or we just like to experiment)? Well many know if you’re trying to troubleshoot speakers and their connections, you can connect a 1.5V battery across the wires (it works best if you hold one end on, and tap the other end). This causes the speaker to make a popping sound. But if the woofer cone is visible, you can watch to see whether the cone goes in or out, and which wire is connected to the positive battery pole will tell you if the speaker is positive or negative phase. So, most speakers today are built positive phase, but it wasn’t always so, and if you’re not sure it’s easy to check.
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