Questions on balanced inputs and XLR Cables

[Jon_Logan]

Again, I think this is incorrect. You are sending a +/- signal to the -/+ connection on your amp. This does not mean that simply switching the connections to the speaker terminasl will correct the polarity and correct the phase. You're simply reversing the polarity a second time, which basically is doubling the problem.

At least this is how it was explained to me by the engineers at Accuphase. I assumed the very same thing you did, but it was clear from Accuphase that this would just make things even worse. Imaging would be even further off center and bass could be more flabby than before.

Maybe they are wrong. Just passing the info.

Well, this is a case where two wrongs do a make a right.
180 degrees + 180 degrees is 360 degrees, or 0 take your pick. Unless you're saying that the signal is delayed by one cycle. Which cycle would that be? 100Hz, 1000Hz. What do you mean?

 

[whoaru99]

Well, this is a case where two wrongs do a make a right.
180 degrees + 180 degrees is 360 degrees, or 0 take your pick. Unless you're saying that the signal is delayed by one cycle. Which cycle would that be? 100Hz, 1000Hz. What do you mean?

This.

With regard to any actual phase issues I don't see how it would be any different regardless of polarity. Both channels are going through the same circuits either way. The amp would have to have something different in one channel vs the other to get channel-to-channel phase problems, again, regardless of any absolute polarity issue.

 

[PrestigeWW]

Well, this is a case where two wrongs do a make a right.
180 degrees + 180 degrees is 360 degrees, or 0 take your pick. Unless you're saying that the signal is delayed by one cycle. Which cycle would that be? 100Hz, 1000Hz. What do you mean?

Well, I'm trying to figure this our myself, having zero engineering background. Maybe we should go back to where I started. This was explained to me as a phase issue, not a polarity issue. It's my understanding (albeit limited) that having the wrong polarity can take the signal out of phase, but fixing the polarity after the fact will not put it back into phase - in fact, it might make things worse.

I found this article which I think is relevant to the discussion: http://www.planetoftunes.com/sound/polarity_and_phase.htm. It seems the issue maybe more with timing. Obviously I need to read more to get a better understanding, but this at least seems to support what the guys at Accuphase were telling me.

 

[whoaru99]

Phase indicates an offset with regard to time. If the signal voltages are simply reversed it is only a matter of polarity because the signals are merely upside down, for lack of better terms, not shifted in time from each other as would be the case for phase.

So, in the previous example, if the signals are "upside down" because the + and - between pre amp and power amp are reversed, simply reversing the speaker lead connections "rights" the signal. There is no timing difference thus it's not a phase issue.