For hifi systems (stereo or Home theater), as long as all the speakers are wired the same way, it doesn't matter .... all of the speakers will be in the same phase. You are referring to what is called relative phase, which means that the connections assure that both speakers are moving in the same direction at the same time. If relative phase were to be incorrect, the symptoms would be extreme and obvious -- vague diffuse images, poor bass, etc. The original poster is referring to what is called absolute phase, which refers to the outputs of BOTH channels being inverted in phase with respect to the program source. That will have sonic effects which are subtle, but will definitely be audible to some people listening to some recordings on some systems. Particularly on sharp transients, where the leading edge will have the wrong polarity (the ear being particular sensitive to the leading edge of transient waveforms, compared to what follows during the next fraction of a second). An inversion of absolute phase in a preamp or power amp can and should be corrected by reversing the positive and negative speaker leads on both channels. It would be more problematical if the inversion were in a source component, because correcting it for that component would create a similar problem for the other source components. Regards, -- Al |
On typical poorly recorded, heavily multi-miked, heavily processed material, absolute phase (or polarity, as Dopogue points out) will clearly make either no difference or a random difference. On string instruments, and many other instruments as well, I'd imagine it would also make no discernable difference, as Ghstudio points out.
However, on a high-quality audiophile caliber recording, that is done using just two or three microphones, that is minimally processed, and especially one that contains sharp percussive sounds, you can find many comments by equipment reviewers and others indicating that there will be subtle but audible degradation if polarity is inverted.
As Dopogue alluded to, some preamps even provide for on-the-fly polarity switching via remote control.
My own philosophy has been that it's easy enough to keep the system phase correct (unless, as I mentioned previously, the source components differ from one another), so I just do it and don't worry about whether or not having it wrong would make a difference.
Regards,
-- Al |
If my preamp inverts and my amp is non inverted then there is no need to correct the phase is that correct?
No, that is wrong, and what Benie indicated has no basis as far as I am aware. Whether the amp and preamp are individually phase inverting or not is of no significance; what matters is the overall system response. The idea is that the polarity of the source material should be the polarity that is fed to the speakers. Also, I must say that I am surprised that this thread has produced so much discussion of whether or not absolute phase/polarity makes an audible difference. Just make the system polarity correct, and whether or not polarity makes an audible difference on your system with your recordings then becomes irrelevant. If it does make a difference, your system will then be optimized for best results on those recordings on which it is likeliest to make a difference (audiophile-caliber, simply mic'd, minimally processed recordings, particularly those containing sharp percussive sounds). If it doesn't make a difference, then nothing will be lost by connecting that way. It's as simple as that. Regards, -- Al |
"[If my preamp inverts and my amp is non inverted then there is no need to correct the phase is that correct?]"
Yes that is correct!
Whether you hear a difference or not. This is the correct way. Can you kindly offer either a technical explanation for that claim, or a link that would provide one? I don't see any basis for that claim whatsoever, as I indicated above, and I have never heard such a claim before. Regards, -- Al |
I'm not a tech, are you?
But I have had it explained to me by a very highly skilled Designer and I don't mean someone into DIY.
As far as a article about: Google is your friend!
Can you kindly offer either a technical explanation saying how I might be incorrect, or a link that would provide one?
I am not talking about, Recording or Speakers!!! Since you asked, I have both Bachelor's and Master's Degrees in Electrical Engineering, and more than 30 years experience as an electronics circuit designer and manager (although not in audio). I also have close to 30 years experience as an audiophile, and I am widely read on the subject, including high end publications (TAS, Stereophile, etc.), mainstream publications, the Journal of the Audio Engineering Society, etc. I have never in all that time encountered the claim you have made, that inverting preamps work best with non-inverting power amps, and vice versa. By that logic, every properly set up system should invert absolute phase/polarity overall. That conflicts with everything that has been written indicating that maintaining absolute phase can be important in some systems with some recordings, to a subtle degree. You can start with the papers that Jea linked to. I understand that you are not talking about the recording or speakers. You appear to be saying that somehow a preamp/power amp combination will function best together if the combination of the two components is inverting. As I say, in all of my experience that I cited above, I have never encountered such a claim. Likewise, I have never encountered any claim that having a combination that is non-inverting is necessarily better, either, other than the fact that it maintains the polarity of the recording without having to interchange speaker connections. So I don't think that asking me to provide a link that will "prove a negative," so to speak, is quite a fair question. Questions that have no basis tend not to be discussed. Regards, -- Al |
Adampeter -- Re absolute polarity checkers, looking at their website I suspect that the Smart Devices units that were suggested as possibilities in your other thread are no longer available.
In any event, they may very well not be worth the expense, considering especially that you would only be using them once, at least until you were to replace a system component.
I suggest playing a few high quality audiophile-oriented recordings that were made using just 2 or 3 mics (that will probably be indicated in the album notes), and that contain a lot of percussive sounds.
Then re-listen with your speaker connections reversed. See if you hear a difference in the sharpness, crispness, and realism of the leading edge (the very beginning) of the percussive notes. If you do, use the connection polarity that sounds best. If you don't hear a difference, assume the power amp is non-inverting, and connect plus to minus so that the inversion in your preamp is corrected for.
On another note (no pun intended :)), re the statement that 50% of recordings are out of phase, I would go further, and put it a little differently.
I would say that on 90+ percent of recordings, the whole concept of absolute phase or polarity is meaningless. The great majority of pop recordings, and the majority of classical recordings as well, are processed through complex multi-track consoles where they are subjected to a bewildering array of effects and mixing. Not to mention that the original takes were probably done with a virtual forest of microphones (particularly in the case of typical poorly engineered recordings of symphony orchestras). The end result, when it comes to absolute phase or polarity, is inevitably a random hodge-podge of different sounds with different phases.
So even if you had a preamp that provided on-the-fly polarity control, if one setting sounded better than the other on a particular recording it would more likely be due to random synergy than to your system preserving the "polarity" of the recording.
Getting the polarity of your system correct is relevant primarily to the unfortunately very small percentage of recordings that are well engineered, using purist techniques. But then again, those are the recordings that we Audiogon'ers tend to have particular interest in.
Enjoy!
-- Al |
Why argue the point? Just do what the manual says. What's so difficult about that? Because all the manual can tell you is if that particular component inverts. But what counts is that the system as a whole should not invert, which as has been explained means that the total number of inverting components and inverted connections should be an even number (0 or 2 or 4). As to "why argue the point," that was exactly what I was getting at in one of my earlier posts. Just get the overall system polarity correct (i.e., non-inverting), and then you don't have to worry about whether or not it makes a difference. Regards, -- Al |
Rodman -- Good references; thanks!
Jea -- Thanks for posting those results. The thing I wonder, though, about preamps that have polarity reversal capability, is if there may be an additional significant variable present. When you reverse polarity, you are not only reversing polarity but you are changing the circuit configuration in the preamp, either adding or removing or selecting a different active stage somewhere in the signal path. So I'd be a bit more cautious drawing conclusions from that kind of test than from a test where the polarity of the speaker connections is interchanged, given that the polarity effects being listened for are alleged by many to be subtle at most.
Regards,
-- Al |
Al, remember that when you switch speaker cables you are also affecting wire directionality, or so I've read. In fact, I remember Doug Blackburn writing an essay on polarity suggesting that the primary audible change you hear (if you hear ANYTHING) is the effect of wire directionality rather than polarity. IME, there IS a more pronounced effect from switching speaker wires rather than changing polarity via the preamp's remote. Anyone for listening to some music? Dave Hmm, some interesting food for thought. I'll say first that I am not in a position to take a position on cable directionality, but I have the following questions and comments: 1)Which end did you switch? Interchanging + and - at the speakers would not change cable directionality -- the electron flow would be in the same direction through each wire, and in the reverse direction only within the speaker. Interchanging at the amplifier end would reverse the direction of electron flow through each leg of the cable. 2)Was your experience with speaker cables that were basically unshielded wire, or did they incorporate passive networks (a la MIT) that might have been direction sensitive, or did they perhaps have shields (whose physical configuration and grounding might contribute to directionality). 3)In this reference, http://www.6moons.com/industryfeatures/polarity/polarity.html, it is stated that reversing polarity at the amp end can reduce overall distortion, by causing amplifier-generated harmonic distortion to be out of phase with speaker-generated harmonic distortion. I haven't thought that through sufficiently to conclude whether or not it makes any sense, and offhand it is very conceivable to me that it does not, but if so perhaps that was a factor in your findings. Regards, -- Al |
Will the mono setting on my preamp help me in any way to determine correct phase via listening tests? Well, maybe a little bit, by cancelling out the stereo information and simplifying the sounds you are listening to. As you probably realize, the mono switch makes for a very convenient way of checking relative phase (that the two channels are in phase with each other). In mono mode if relative phase is correct a sharply focused image will be heard centered between the speakers, and if it is incorrect an unfocused diffuse image will be heard. But I would expect the relevance of the mono switch to assessing absolute phase/polarity to be subtle at most. Regards, -- Al |
