M60's Surprisingly Out of Phase!

Posted by: leefarber

M60's Surprisingly Out of Phase! - 08/23/13 07:18 PM

Now this is strange. I've had a pair of M60's for the past two years and have enjoyed them. They have dual binding posts, connected to my Sunfire Cinema Grand Series II Amp and a Marantz 8801 Pre/Pro. I've enjoyed the sound, but something always felt lacking, and I could never put my finger on it.

Today I was playing around with a calibration disc, and just for the hell of it, I ran the speaker polarity test. The out of phase test tone should have been softer than the in-phase test tone, but it wasn't! I found some other polarity tests online and ran those. Lo and behold, my M60's appeared to be out of phase!

I checked the wiring (which I had done myself) and everything was correct... Red to Red, Black to Black. But despite this, I went ahead and swapped the polarity of one speaker (both pairs of binding posts), and the result was a significant improvement! And this time, it passed all the polarity tests!

So my question is: how could this be possible, given that the wiring was correct? Could one of the M60's be cross-wired inside the speaker, forcing me to compensate by reversing polarity on the binding posts? Again, I checked and re-checked the wiring. It was absolutely correct before.

As an aside, whenever I ran an Audyssey calibration, Audyssey always reported that my speakers were out of phase. I disregarded that, as I knew it was wired correctly, and I've read that Audyssey can be prone to errors, but now it all makes sense.

Can someone help me explain what's going on here? Thanks in advance!

Lee
Posted by: SirQuack

Re: M60's Surprisingly Out of Phase! - 08/23/13 08:31 PM

My m60's and current m80's also have dual binding posts, which is how Axiom manufactured them, but you should leave the strap on and only use one pair, was this the case? Just curious since you mentioned the dual posts and "buy wiring" would not be a benefit if that is what you were doing...
Posted by: Socketman

Re: M60's Surprisingly Out of Phase! - 08/23/13 08:38 PM

Its could be out of phase any where along the chain from the pre pro on. All speaker manufacturers check the speakers at the end of the line I cant really see one sneaking by but I guess it could happen. I would pull the binding posts out and take a look. The speaker connectors at the drivers are 2 different sizes so there is no way they could be reversed. Truly a strange occurance. I know audyssey often tells me my speakers are out of phase but the next time round it will say they are fine. Maybe Ian or Andrew will see this post and have some insight.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/23/13 08:54 PM

Originally Posted By: SirQuack
My m60's and current m80's also have dual binding posts, which is how Axiom manufactured them, but you should leave the strap on and only use one pair, was this the case? Just curious since you mentioned the dual posts and "buy wiring" would not be a benefit if that is what you were doing...


No, I don't use the strap. The Sunfire Amp has two sets of terminals for the mains and center channel, what they call a "Voltage Source" and a "Current Source". You can choose one or the other for a slightly more "tube-like" or "solid-state" sound, or you can bi-wire as I've done.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/23/13 10:00 PM

Originally Posted By: Socketman
It could be out of phase any where along the chain from the pre pro on.


The only other part of the chain are the XLR's going from the Pre/Pro to the Amp, but how could they be out of phase? It's only one connection per channel.
Posted by: JohnK

Re: M60's Surprisingly Out of Phase! - 08/23/13 11:01 PM

Lee, that's rather puzzling at this point. Just to take some of the rather gimmicky amplifier terminal setup out, try the normal "voltage" terminals(presumably lower output impedance and more accurate sound)alone with the speaker straps connected. See if the out-of-phase condition still exists.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/24/13 02:22 AM

I'll give that a try and report back. Thanks for the suggestion, John.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/24/13 12:42 PM

Unfortunately, I can't locate the straps, so I've emailed Brent to see if he could send me two pairs.
Posted by: a401classic

Re: M60's Surprisingly Out of Phase! - 08/24/13 07:54 PM

In the mean time you could use a short section of speaker wire to jumper between the posts. Depending on the gauge, there should be room for a pair of wires in each post.
Posted by: JohnK

Re: M60's Surprisingly Out of Phase! - 08/25/13 12:32 AM

Ditto.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/26/13 08:35 PM

So here's a brief update: I strapped the two sets of binding posts together on both speakers so they are no longer bi-wired. And the problem persists: one of the speakers is out of phase relative to the other. The only way that these speakers pass the FOUR different polarity tests I put them through is if one of the speakers has their polarities reversed (it doesn't matter which one).

Brent had me only connect one of the speakers at a time and do the tests on each speaker. When I did that, there was no difference in the test tones between in-phase and out-of-phase. Brent took this to mean there couldn't be a problem with either speaker, but now that I think about it, I have to disagree, since the two speakers are out of phase RELATIVE TO EACH OTHER. Testing one at a time would be inconclusive.

It seems the only thing left to do it grab another pair of speakers (I have an old pair of m22's in storage) and see if the problem persists. If it does, then the problem must be with the amplifier. If it doesn't, then one of my M60's must be wired incorrectly.

I'll report back soon. In the meantime, I'd welcome any thoughts or suggestions. Thanks!
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/26/13 08:38 PM

And I should add that since reversing the polarities on one of the M60s, the difference is incredible. Bass is tight, sound is more directional and clear. It's night and day.
Posted by: SirQuack

Re: M60's Surprisingly Out of Phase! - 08/26/13 08:41 PM

that would be a good test, you could also try this simple test with a 9volt battery to see which direction the woofers travel, that will tell you if they are in or out of phase.

http://www.youtube.com/watch?v=YR2sXTVtLMc
Posted by: JohnK

Re: M60's Surprisingly Out of Phase! - 08/26/13 10:00 PM

Lee, if each individual speaker is connected internally with the correct polarity, then taken together they'll be in phase with each other. If the test you ran showed correct polarity in each that should answer the question. The battery test Randy linked(1.5 volt can also be used, although cone movement is less)can double check this. Also, using the M22s is yet another test.

If it appears that the amplifier is the culprit, connect different channels to see if removing one of them(possibly wired internally with reverse polarity)from the circuit also removes the phase problem.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/26/13 10:33 PM

Thanks guys. I've hooked up the m22's and had the same result! Plus, I did the battery test, and everything checked out. I can now verify with 100% certainty that it is NOT the speakers.

I never had this problem with the amplifier before. The only thing that has changed is that I replaced the RCA interconnects between Pre/Pro and Amp with balanced XLRs. Could they be the culprit? I can't imagine there's a way a single XLR cable could invert polarity.
Posted by: ClubNeon

Re: M60's Surprisingly Out of Phase! - 08/26/13 11:29 PM

If someone built the XLR wrong, it could be the cause. Do you have a volt meter with continuity checking? Test the pins end to end, and see if any don't match up.
Posted by: JohnK

Re: M60's Surprisingly Out of Phase! - 08/26/13 11:41 PM

Possible. Keep in mind that balanced XLR connections have two central conductors rather than the one in a coaxial cable. They work by sending out two signals, with one inverted 180 degrees in polarity, which are then in effect "re-inverted" in a balanced receiving unit(i.e., the amplifier). It's unlikely this this is the basis for the problem if you didn't notice a deterioration when you first used the XLRs, but in any case try it with the coaxials back in.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/27/13 12:31 AM

If I'm being honest, I think there was a deterioration when I switched to XLR from RCA, but I was trying to convince myself the XLRs were better! I'll try switching back to RCAs and see if that does the trick.

I got the XLRs from Blue Jeans cable, so I know they're well-made. Could it have something to do with the fact that my Sunfire amp is from 2000 and the Marantz Pre/Pro is from 2012? I found this thread which seems to pose the same question:

http://www.htguide.com/forum/showthread.php?30942-XLR-Polarity
Posted by: tomtuttle

Re: M60's Surprisingly Out of Phase! - 08/27/13 01:01 AM

Fascinating story! Thank you for sharing this journey.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/27/13 01:07 AM

I also found this site:

http://www.clarkwire.com/PinOutXLRBalanced.htm

Which says specifically, "Some manufacturers, especially in vintage equipment, do not follow this standard and instead reverse the polarity of pin 2 and 3."

But by glancing at the Sunfire manual, it doesn't appear as if the polarity is reversed. Can someone verify that for me? It's online here:

http://www.sunfire.com/manuals/Cinema%20...er%20Manual.pdf
Posted by: ArthurC

Re: M60's Surprisingly Out of Phase! - 08/27/13 07:49 AM

I'd have to agree on the manual and XLR spec having the +,- reversed. Still, if both channels are similarly wired, the output signals would still be in phase with each other.

Now if one cable were wired differently that could explain it. Continuity check will answer that.

/a
Posted by: ClubNeon

Re: M60's Surprisingly Out of Phase! - 08/27/13 09:53 AM

Originally Posted By: leefarber
I got the XLRs from Blue Jeans cable, so I know they're well-made.

Blue Jeans' XLRs are hand soldiered, so there is a possibility of human error involved. And I bet if there is an issue, even after this time, if you e-mail them, you'd get a free replacement.
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/27/13 12:16 PM

Solved it! (Well, more or less).

I replaced the 5 XLR cables connecting the Pre to the Amp with RCAs, and now everything is as it should be. Honestly, I don't know what could have caused this, but I'm not going to worry too much about it. I use very short runs of cable (less than 3 feet), so it would seem there is no advantage to XLR over RCA anyway.

Either I had a faulty cable, or there is some incompatibility between my Pre and my Amp. I'm leaning toward the latter. I found an interesting passage in the Marantz 8801 manual here:

Quote:
AV8801 BALANCED XLR PRE OUT terminal PIN arrangement:

1 GND (Ground)
2 HOT (+)
3 COLD ()
The PIN arrangement in this device uses the European method.
In the USA method, 2 is COLD, and 3 is HOT.
When connecting a device that utilizes the USA type of PIN arrangement, replace
the 2 and 3 plugs on one side of the balanced cable.


This seems crazy to me! So rather than spend any more time on it, I'm just going to be happy with my unbalanced RCA connections and leave it at that! But again, if anyone has any insight, I would be interested to hear it. Thanks again!
Posted by: J. B.

Re: M60's Surprisingly Out of Phase! - 08/27/13 01:17 PM

lee, i've seen the same info on some pro amp sites.
one just has to care about they way they are made up, but for short runs like yours, RCA is excellent.
Posted by: JohnK

Re: M60's Surprisingly Out of Phase! - 08/27/13 11:19 PM

Lee, so the bottom line is that there appears to be incorrect wiring in either one of the Marantz XLR output channels, one of the Sunfire XLR input channels, or one of the BlueJeans XLR cables connecting them. Whichever may be the case, there's already been more than enough concern exercised, so just relax and enjoy the better sound. The coaxial connection is totally sufficient.

The balanced XLR connection is only of benefit in reducing noise in primarily professional applications where there's both a high level of electrical interference and long runs occur through it. Most home setups, undoubtedly including yours, don't experience an interference problem with regular shielded coaxial cables. Reports of substantial XLR benefits, not relating to just noise rejection, exist on some audio forums, but if the equipment used didn't compensate for the double voltage(by having 6dB less gain in the XLR circuitry), causing an increase in loudness at the same setting, this is simply another example of louder sounding better.

Incidentally, both the Marantz and Sunfire units are designed to use the standard pin2 positive convention. Also, the quote from the Marantz manual regarding supposed "methods" is incorrect or at best, outdated. For the correct info on this point, see Bob Lee's discussion here .
Posted by: leefarber

Re: M60's Surprisingly Out of Phase! - 08/28/13 12:24 AM

Interesting! Thanks for clearing that up for me, John. I will certainly just kick back and enjoy the status quo. Out of curiosity, is there a way to open up the XLR cables and check the polarity myself? I'm trying to decide if I should send them back to Blue Jeans to be tested (at my expense if there's nothing wrong with them!).
Posted by: ClubNeon

Re: M60's Surprisingly Out of Phase! - 08/28/13 01:03 AM

A $9 volt meter will easily tell you, and could be useful for other things in the future.

But you might look to see if the shell has a lock screw holding it in place, or itself screws loose from the plug (my balanced cables from Bluejeans are TRS).
Posted by: NOLAGT

Re: M60's Surprisingly Out of Phase! - 09/27/13 02:03 PM

I just cant believe for 2 years you had them out of phase...it must be like getting brand new speakers all over again now that you got them running right....wow lol