Absolute Phase problem

JoeE SP9

JoeE SP9

Senior Audioholic
My buddie and I have recently come across a situation we are at a loss to explain. Everyone should be aware of the effect of absulute phase, if not please read The Wood Effect by Clark Johnson. There are tests on Chesky samplers and Stereophile test CD's to test absolute phase/polarity. Please do not confuse this with wiring speakers out of phase with each other. When my buddy connects his Adcom GFA5800 to his Maggy MG2's in one polarity they sound drastically different than the other. His other Adcom (GFA545) does not exhibit this difference. None of the closet full of amps that I have collected does this when connected to his Maggy's. The big Adcom does not have any DC offset (we checked). We are both aware that there should be a difference when reversing absolute phase but it should be small and subtle not gross and easily audible. When I connect his big Adcom to my ES panels we don't get the same gross differences. The MG2's sound simply wonderful and he has no complaints about the sound. We are puzzled by the gross differences that reversing phase shows. Anyone got any ideas? :cool:
 
D

djoxygen

Full Audioholic
Would you be willing to try to characterize the difference?
 
WmAx

WmAx

Audioholic Samurai
Well, first I would suggest ensuring that this is not due to psychological influence. THeir is no evidence to suggest absolute polarity, itself, as being audible on music program material on properly functioing equipment. The Clark Johnson test you refer to used an assymetrical test signal -- not music. In many cases, special test signals are used to enhance sensitivity to audible phenemena to make it easier to 'hear' the effect. However, relevance must be considered for the end purpose(music playback).

Now, it's only fair to state that I can percieve an effect when changing absolute polarity. However, I have submiited myself to a DBT(abx version) test of the phenomena and failed to score anything more then chance percentages. Psychological subconscious bias at it's finest. :)

ALso, perhaps an unusual non linear behaviour in the chain may somewhoe cause an audible difference? I am not sure.


-Chris
 
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JoeE SP9

JoeE SP9

Senior Audioholic
In one phase the sound is almost as if the speakers were wired out of phase without the loss off stereo. His wife called it going from mono to stereo. He calls it a loss of imaging. I don't really agree with the terms they are using. We are certain this is not a psychological effect. The differences are just too gross. His wife daughter and he and I can hear the difference in another room without being prompted to respond. Casual listeners who are in the listening room immediately hear the difference. As I said in my original question changing absolute phase shows a very small audible difference if any at all is percieved. We are talking gross differences here.
 
D

djoxygen

Full Audioholic
Can't really say, I guess. The descriptions make it sound like you're inadvertently cross-patching the 2 channels or bridging the amp into mono, although I'm not sure how that would be possible without your knowing it.

Are you flipping the cables at the amp or at the speakers?

Any reason you wouldn't hook it up the way it sounds "right" and leave it at that?
 
JoeE SP9

JoeE SP9

Senior Audioholic
Phase

We have tried flipping the speaker cables (Kimber TC8) at both ends. We have replaced or substituted the cables from the pre to power. We have settled on the "phase" that sounds right. We are just puzzled by the differences we hear. :cool:
 
WmAx

WmAx

Audioholic Samurai
JoeE SP9 said:
We have tried flipping the speaker cables (Kimber TC8) at both ends. We have replaced or substituted the cables from the pre to power. We have settled on the "phase" that sounds right. We are just puzzled by the differences we hear. :cool:
Looks like the only way your ever going to find out what's really going on is to perform some detailed signal analysis of the differing conditions. Unless some reads your post that has just happened to have com across this odd problem.

-Chris
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
We have tried flipping the speaker cables (Kimber TC8) at both ends.


I am not sure what this accomlished? Did you do it on both speakers? Maybe you can clairify exactely what you did with them?

We have replaced or substituted the cables from the pre to power.

Again, this will do nothing.

We have settled on the "phase" that sounds right.

Maybe one of your speaker was in fact out of phase with the other, not witht he actual signal itself.

Besides, you have no idea what phase is the correct phase as in the recording, the absolute phase is not in anyones mind to follow.

And, as was stated, you need very special signals and conditions to observ this issue, certainly not in music. You should expand your horizon and read some of the works of RA Greiner who followed up on Johnsons poor work.
 
JoeE SP9

JoeE SP9

Senior Audioholic
Thank you WmAx, although we are satisfied with the sound now we are very puzzled and want to know for curiosity's sake. To clarify for others. When I say we reversed the speaker cables that means we reversed the connections on both cables at one end. We know changing the signal cables should make no difference but the problem is so strange we have tried everything. I began this question by stating that the speakers were in phase. Maybe I should have been more specific. We removed the socks on the maggies and connected a battery to the speaker terminals to make sure that we did not have them wired out of phase with each other (they were purchased used). I am well aware that absolute phase is very difficult to hear if at all. The differences we and other listeners including casual hear are GROSS. It requires no prompting for even casual listeners to say "it sounds better now". :cool:
 
surveyor

surveyor

Audioholic Chief
Correct phasing is essential to assure that left and right spealers are working in unison rather than opposing each other.
Each speaker has a red positive (+) and black negative (-) connections. Each should be connected the same way to your amp and speakers.
To audibly check phasing, play some music rich in bass frequencies and switch between mono and stereo on your preamp. When you are standing midway between the speakers you can identify an out of phase hookup by a weakening of bass when mono is selected. If phasing is correct, the bass is unchanged. To correct, simply reverse the leads of one speaker.

Cheers :cool:
 
JoeE SP9

JoeE SP9

Senior Audioholic
I tried to make clear that the inter speaker phasing was always correct ie: a positive voltage applied to the red bannana socket caused a forward motion, both speakers were connected in phase with each other in this respect. What is puzzling is that there is an enormous difference when the speaker cables are reversed. Insted of red to red and black to black, do red to black and black to red with both. What differences you hear are supposed to be damn near inaudible if audible at all. This is not what is happening. We really don't care if it's red to red or red to black etc. We are just puzzled by the large difference we hear. We settled on the "phase" that sounded best. Black to red etc.
 
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