Balanced XLR cable - polarity hot / cold matching between components- critical?

Discussion in 'Audio Hardware' started by TheVinylAddict, Jun 23, 2019.

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  1. TheVinylAddict

    TheVinylAddict Look what I found Thread Starter

    Location:
    AZ
    I'll cut right to it --- I have an Accuphase C-2410 line stage / preamp, and it is configured for XLR balanced with Pin 2 (-) and Pin 3 (+). (of course pin 1 is ground). Same XLR polarity configuration with the Accuphase C-27 phono preamp I own. Both Accuphase components are Made in Japan, 100V components.

    I recently purchased a Parasound JC3+ phono preamp to run in XLR balanced mode to the C-2410 line stage, in addition to the C-27.

    But the Parasound JC3+ XLR polarity is Pin 2 (+) and Pin 3(-). For that matter, so is the Parasound A21 amp, which the C-2410 line stage feeds! Both the A21 and JC3+ are Pin 2(+) and Pin3 (-)

    Note I have been running the JC3+ into the C-2410 for a while now in XLR before this polarity mismatch dawned on me. The C-2410 has also been feeding the A-21 for a while also in XLR balanced mode with the same mismatch. I didn't notice any issues and there definitely is not any hum or buzz or other untoward noises in the signal chain. Also note pushing the "Phase" button on my preamp appears to have no impact on sound (at least audibly). But I am not an expert in this area, and of course just because you don't notice does not mean you should be doing it!!!

    Realize of course I did do some reading on the topic - this is not the first I have researched or sought feedback - just looking for more thorough discussion hopefully. Feedback I have read ranges from "it doesn't matter" to " it is critical" --- surprise, surprise like everything on the internet it runs the gamut and you can find any answer you want!

    So, what do you think? Should I get my XLR cables re-pinned to swap hot and neutral in the right spots? Or does any of this matter?

    Additional info: The XLR cables I own are of two types - one is the Mogami 2549 (made by ProAudio LA) and the Belden 1800F (made by Blue Jeans). Both have Neutrik Gold connectors. Not that this matters, just FYI.

    EDIT:
    I should also note -- the Accuphase C-27 has a switch on the back to toggle polarity between Pin2 and Pin3 --- but the C-2410 line stage does not.

    The C-2410 does have a Phase button, but I don't think that is related to the XLR polarity?
     
    Last edited: Jun 23, 2019
  2. John Buchanan

    John Buchanan I'm just a headphone kind of fellow. Stax Sigma

    Most "phase" buttons are the same as a polarity switch.
     
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  3. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    If there is an odd number of polarity swaps in your system, it will invert phase.If that bothers you, you can indeed get a cable made up to swap polarity. If you use only one source, you can swap the red and black wires at the speakers instead.

    As @John Buchanan said, the "phase" button can also accomplish this.

    Most of the time, I can't hear absolute polarity. When I can, it's not obvious which I prefer. Different listeners are affected differently, so let your ears decide.
     
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  4. John Buchanan

    John Buchanan I'm just a headphone kind of fellow. Stax Sigma

    An excellent summary!
     
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  5. TheVinylAddict

    TheVinylAddict Look what I found Thread Starter

    Location:
    AZ
    That is why I posted - what about it should bother me, and secondarily is there any harm in it other than perhaps hearing some subtle difference (which
    I am not sure still what that difference will sound like)?

    What am I listening for - because I don't hear anything untoward currently as I stated?

    Also, yes aware that the Phase button inverts polarity, but pressing makes no difference and why I was unsure if it was affecting the balanced inputs / outputs.
     
  6. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    If pressing the phase button doesn't make a difference to your ears, you've answered your own question -- you are among us who think that absolute polarity is not a big deal.

    I've been told that percussion is a good test, if you are interested in pursuing discontent any further. ;)
     
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  7. The FRiNgE

    The FRiNgE Forum Resident

    On the topic of listening for polarity, and if this makes an audible difference.. I need to do more research on this. Theoretically we should be able to tell the difference since a "plosive" force should "push" air, or cause compression. A shock wave is a prime example, a volcanic explosion, sonic boom, etc.. that the initial force is positive, not negative. The attack of a stick hitting the head of a snare drum is negative, from the drummer's perspective. (and a microphone placed above)

    Polarity should make a difference only in the transient attack.. I doubt there isn't any difference in the regular oscillation of a sound. (a tone produced is the periodic repetition of compression and rarefaction and makes no difference) Musical tone should not be affected by polarity. Not to confuse this with improper recording practices.. more than one microphone incorrectly placed on the same instrument will definitely cause audible differences... the ultimate out of phase mix produces no sound.

    I think for the sake of discussion on point, does reversed polarity on a musical source make a difference, I would say generally no. However a highly dynamic source with sharp transients should make a difference. It makes a difference that the attack of a beater of the bass drum "pushes" air in a live setting, (plosive force) therefore our sound system should also push air. The woofer must "push" outward (positive polarity) to produce the plosive attack that hits you properly in the torso.

    Example of strong positive polarity, nasty thing:
     
    Last edited: Jun 24, 2019
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  8. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    Which XLR pin is hot differs between the convention of pin 2 being + and pin 3 being -, and Japan which for some reason have it the other way around. So when a rig involves both Western and Japanese balanced there is a phase inversion.

    I have no idea why Japan chose the opposite signal sense as compared to the rest of the world.

    Whether or not you can hear phase or not probably has more to do with loudspeaker technology as compared with audibility of absolute phase - and here is the reason.

    Suppose you are listening to an orchestra. At any position you are sitting you will hear every instrument in a different phase - since the sound reaches you from each violin at a different time, from the brass section a bit later etc. And noone sits there and listens to a concert (whether classical or rock) and cares one jot that the phase is totally scrambled.

    Now you end up in your listening room to two loudspeakers in an attempt to create a phantom image of some real event. The problem is that loudspeaker drivers are badly non-linear. Depending on the driver design, it will almost certainly have a different response when the driver kicks outward as compared to kicking inward. And that generates a perception signal phase one way round sounds different - or preferable audibly - than the other way round.

    But it depends on the driver design. If perfectly symmetrical (ie if the driver designer has done his job perfectly and the driver is built repeatedly) then phase is likely to be less of an issue.

    If anyone wants a little bedtime reading about why drivers are massively imperfect, here we go https://www.klippel.de/fileadmin/_migrated/content_uploads/Loudspeaker_Nonlinearities–Causes_Parameters_Symptoms_01.pdf
     
    Last edited: Jun 24, 2019
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  9. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    That is also the reason that very expensive loudspeakers with multiple bass drivers (there are some with 10 or more 15" drivers per side) or horn driven, sound clean. The thing is that distortion is very dependent on the amplitude of motion - near the excursion limit of say 10mm on a 12" driver it will be generating 0.3-0.5% harmonic distortion. And it sounds very much worse that that because the ear's sensitivity is higher as the frequency goes up towards the midrange (Fletcher-Munsen curves). So the harmonic distortion components of a bass driver are extremely audible, and can easily sound louder than the fundamental.

    But if you have ten drivers, each only has to do 1/10th the amplitude for the same loudness. And that produces much, much less distortion. Same thing with horns - a horn is an acoustic impedance matching device, so the driver has to work 1/100th as hard for the same loudness. And that is why old cinema loudspeakers used horns - you could play loud and clean.

    Of course the downside is there is no free lunch - any system that produces really clean bass is BIG! And expensive.
     
  10. TheVinylAddict

    TheVinylAddict Look what I found Thread Starter

    Location:
    AZ
    Maybe I will just remove all doubt and swap pins 2 and 3 (hot / neutral) on one end of the XLR cable(s) that connect two pieces of equipment that aren't alike. Having it right can't hurt! :)

    I do like on the Accuphase C-27 that there is a switch on the back to facilitate -- but unfortunately there is not on the C-2410 line stage!! So there is a current mismatch on JC3+ ---> C-2410 and on C-2410 ---> A21 XLR.

    Actually, I think I will do that right now for the XLR cable between the JC3+ and the C-2410 --- I just had two meetings cancelled so have some time --- just flipped the soldering iron on.......... report back later.
     
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  11. TheVinylAddict

    TheVinylAddict Look what I found Thread Starter

    Location:
    AZ
    OK all done - whether or not I can hear it, etc. is now inconsequential as I have swapped the hot / neutral on one end of two of my XLR cables.

    Playing right now -- not sure I hear any difference LOL :) --- but everything is now phase matched throughout the signal chain!!

    [​IMG]
     
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  12. John Buchanan

    John Buchanan I'm just a headphone kind of fellow. Stax Sigma

    It appears that both of your Accuphase items have polarity switches/buttons - one is labelled "polarity" and the other "phase". all itemised several times above.
     
  13. TheVinylAddict

    TheVinylAddict Look what I found Thread Starter

    Location:
    AZ
    Yes I know I own the equipment, and mentioned the switches and buttons as such above. But I am not sure you are understanding the entire situation.... not sure what you are trying to convey.

    There are multiple systems / components at play simultaneously and by re-wiring two of the cables cables and I won't have to always think about flipping switches or pressing buttons. It is now all phase matched.

    If I am playing a TT through the C-27, it is OK to the C-2410 (both Accuphase) but then further down the chain C-2410 to A21 amp is not. Then if playing a TT through JC3+, then not OK to the C-2410, then reversed again to the A21 (which may actually cancel)

    This way by getting cables right it is done, never have to press any buttons, flip any switches or ever have to think about it.

    For the foreseeable future I have components with different polarity on XLR, and plan on running balanced (it sounds incredible) --- so having two sets of XLR cables with swapped polarity on one end is the price I pay! I have the cables marked! :)
     
    Last edited: Jun 24, 2019
  14. lonelysea

    lonelysea Ban Leaf Blowers

    Location:
    The Cascades
    I have a similar balanced XLR phase issue, one I’m hoping is less complicated:
    I’m getting an Accuphase DP-560 CD/SACD player to use with my Yamaha A-S3000 integrated amp. The “normal” phase setup on the Yamaha has pin 2 HOT (+) and pin 3 COLD (-), looking closely at the first pic, but the Accuphase appears to have the normal setting the reverse of the Yamaha (pin 2= COLD, pin 3= HOT). Both pins 1 are GROUND, btw.

    Both units have phase switches (see pics). Which one do I switch?
    Thanks for any help!

    [​IMG]

    [​IMG]
     
  15. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    Some Japanese manufacturers have pin 3 hot and pin 2 cold, which is the opposite of convention. No idea why.

    Stax used to be 3 hot and 2 cold (like with the legendary SRM-T2), but now they have converted to the conventional phasing.
     
  16. touch33

    touch33 Active Member

    Location:
    Houston
    OK, here goes: Old SoundMan shares what he knows...

    1) “phase” = time (when comparing two signals). Phase is expressed in “degrees” based on the concept of any wave-type signal having a repeating “cycle” of 360 degrees.

    2) “polarity” is an absolute 180.000000 degrees of phase difference, no more and no less.

    3) Combining two identical signals that have ANY phase difference between them results in mathematical/predictable “peaks & valleys” in the (combined) resulting signal.

    4) Combining two identical signals with 180 degrees of phase difference between them (“out of polarity”) results in absolutely no resulting signal at all, since we all know that two true opposites cancel each other out completely.

    5) Once we get our cables to be able to carry our precious signal without undue signal loss (assume that we have) the biggest problem we face is trying to reduce/eliminate the effect of any form of outside electromagnetic interference adding itself to our signal — what we call “induced noise”.

    The good folks at Bell Labs realized that even the best electromagnetic wire screening (“shield”) could only prevent most — but not all — of any outside interference from dirty-ing up the pure signal, and these guys were trying to send signals over MILES of cable length (not just the few feet we audio geeks deal with). Long story short: some Genius figured out that they could transmit two different versions of the same signal down separate conductors in a single (shielded/ground-referenced) cable jacket — with one of the signals’ phase shifted 180 degrees (or “flipped out of polarity”) compared to the other — and then add them together at the receiving end as long as they “unflipped” the polarity of one of the conductors”. No big deal, right?

    WRONG! Recognizing that any outside interference would be equally injected onto BOTH signal conductors, un-flipping the polarity difference of ONE of the conductors (making both signals now the same polarity) would also flip the polarity of the injected noise on the same conductors — which, when summed together at the receiving end, would result in the noise being completely cancelled out. Brilliant!

    And that’s how a differential (“balanced”) cable works: the transmitter flips the polarity of one signal conductor, interference affects both conductors equally, and the receiver reverses the polarity of one conductor before summing the two signals — double the signal and no noise. Voila!

    SO... it doesn’t matter which XLR pin is + (“hot”) and which pin is - (“not”) UNTIL you start talking about using two or more signal channels with each other — like in a stereo system. Get your left and right channel cables “out of phase (polarity)” with each other — either by inconsistent XLR wiring or by “swapping the red/black wires on one speaker” and the result is the same: that “hole in the middle of my skull” sound we all recognize when walking past a sound system in Best Buy...

    Regarding XLRs: the IEC international standard for “differential audio cable” has always been “pin 2 hot”, but being contrary Americans, we (and the Japanese who catered primarily to the US market at that time) used “pin 3 hot” up until the late 1970’s when we finally fell in line with the rest of the world.

    Reality: as long as both ends of all XLR cables are wired the same way you’re not going to hear any difference — and since you don’t have a clue as to how the recording studio was equipped you also have no idea if that initial kick drum impulse (which was most certainly a “push” when the beater hit the rear drum head) got “flipped” along its way from the microphone(s) and consoles and processors and recorders and mastering systems and finally to your woofers...

    (BTW: easy way to test speaker polarity is to take a 9V battery and BRIEFLY touch it to the speaker wire feeding each speaker and see which way the woofer “pops” in or out — but do be quick about it or you’ll burn a coil...)

    So. There.
    (please pardon any thumb-induced typos/wordos/etc.)

    Cheers,
    Bruce
     
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  17. Steve Hoffman

    Steve Hoffman Your host Your Host

    Good times.
     
  18. lonelysea

    lonelysea Ban Leaf Blowers

    Location:
    The Cascades
    My brain’s polarity just got inverted.
     
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  19. Tim S

    Tim S Senior Member

    Location:
    East Tennessee
    Good! You did it right! Someone floated the idea of making or buying a phase inverting cables - no, don't do it! Somewhere, sometime somebody is going to use these cables with no idea of what they are and potentially create an audio nightmare that will be nearly impossible to diagnose and fix.
     
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  20. lonelysea

    lonelysea Ban Leaf Blowers

    Location:
    The Cascades
    I’m guessing that if I invert the polarity on the cd player (using the switch, 2=HOT), it will match the polarity of the Yamaha amp’s input.
    Also guessing it makes no difference which component I choose to “invert”.
     
  21. Mike-48

    Mike-48 A shadow of my former self

    Location:
    Portland, Oregon
    That sounds right to me.
     
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  22. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    on the yamaha the phase switch does reverse the hot and cold pinouts on the balanced connections. switch both phase buttons on the amp and connect away.
     
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  23. lonelysea

    lonelysea Ban Leaf Blowers

    Location:
    The Cascades
    The Accuphase cd player has the same switch. Is there any practical reason to favor switching one component over the other? Pretty sure I’m overthinking this stuff but I can’t help being curious about it.
     
  24. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    no reason, a switch is a switch, picture what is happening inside the chassis. one or the other just not both :) possibly the one that is easiest to get to ?
     
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  25. Just Walking

    Just Walking Forum Resident

    Location:
    UK
    “Only the common-mode impedance balance of the driver, line, and
    receiver play a role in noise or interference rejection. This noise or
    interference rejection property is independent of the presence of a
    desired differential signal. Therefore, it can make no difference
    whether the desired signal exists entirely on one line, as a greater
    voltage on one line than the other, or as equal voltages on both of
    them. Symmetry of the desired signal has advantages, but they
    concern headroom and crosstalk, not noise or interference rejection.”
    IEC Standard 60268-3 (2000)

    The purpose of copying that out is to pop the bubble that balanced connections must have equal and opposite polarities. That is just not true. The sole reasons to go balanced are (a) interference rejection and (b) immunity to hum loops.

    But all that is down to the common mode impedance balance - AKA CMRR. All the relevant parameters are listed for well designed and specified equipment (usually pro-audio gear), and specifically for line driver and receiver chips manufactured by THAT. They are never specified as far as I know for domestic audio equipment, regardless of price.
     
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