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#45766 - 03/24/03 11:38 AM Re: 6ch anlog input reversed polarity on sub channel
soundhound Offline
Desperado

Registered: 04/10/02
Posts: 1857
Loc: Gusev Crater, Mars
In the many measurements I've done, a 180 degree polarity reversal will cause a suckout of about 6db at the crossover frequency in cases where the woofers of the mains and subs are placed next to each other, when observed on a RTA. The farther apart the placement, the less the suckout will be, but depending on the place where you are measuring, there will be random peaks and nulls because of the acoustics of the room. These peaks and nulls will occur whether the woofers are in polarity or not; they will change in frequency somewhat from in polarity to out of polarity.

While all this is obvious on the screen of an RTA, the audibility with actual program material is generally much less. In addition, changing the polarity of the sub will yield flattest response in some locations and worse response in others.

Generally, I would determine the setting that yields flattest response at the listening position and call it good. Trying to find a setting that is valid in all parts of the room is difficult, and it will get harder the farther apart the sub is placed from the other speakers.

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#45767 - 03/24/03 03:51 PM Re: 6ch anlog input reversed polarity on sub channel
Kevin C Brown Offline
Desperado

Registered: 12/11/01
Posts: 1054
Loc: Santa Clara, CA
All of my measurements are at the listening position. (Finally got a tripod last year, so not even dependent on my left arm for holding it in the same spot! )

It *is* hard to explain the *more* out of phase result for DVD-A and the Chesky disc test, except that I am guessing that the test tone is sent to all 5 main speakers and then compared to either info that is crossed over to the sub from the 5, or a specific LFE signal sent there.

Also, on my system, the difference between in phase and out of phase is night and day. There is a specific music test for this also on the Chesky disc. Bass guitar notes. In phase, you can feel the rumble. Out of phase, you hear the notes, but no rumble. Same-o even when I play the Get Yer Ya Ya's Out SACD by the Stones. You wouldn't think that there's a lot of lower freq content on a disc like this, but there's enough that the difference is easily apparant.

The EFT software has phase stuff in it, I'll take a look and see if there's anything relevant.
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#45768 - 03/24/03 04:01 PM Re: 6ch anlog input reversed polarity on sub channel
The Hun Offline
Gunslinger

Registered: 03/14/03
Posts: 59
Loc: Riverside
Quote:
Also, on my system, the difference between in phase and out of phase is night and day. There is a specific music test for this also on the Chesky disc. Bass guitar notes. In phase, you can feel the rumble. Out of phase, you hear the notes, but no rumble

My observation exactly!
I also used the listening position as "reference".

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#45769 - 03/24/03 07:40 PM Re: 6ch anlog input reversed polarity on sub channel
Will Offline
Desperado

Registered: 05/28/02
Posts: 605
Loc: LA's The Place
As I mentioned earlier I have a phase difference when switching between stereo (with sub) and 5.1 (with of course sub).

The difference I hear between in phase and out of phase is the virtual positioning of the sound is centered where it should be, when the speakers and subwoofer are in phase. But the virtual positioning moves away from being centered and sounds just plain wrong, when the subwoofer is out of phase with the speakers. YMMV.

Will

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#45770 - 06/27/03 03:46 AM Re: 6ch anlog input reversed polarity on sub channel
Will Offline
Desperado

Registered: 05/28/02
Posts: 605
Loc: LA's The Place
Did the Outlaws ever acknowledge any polarity problem with the fixed 950, as reported by KCB and others?

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#45771 - 06/27/03 07:06 PM Re: 6ch anlog input reversed polarity on sub channel
DaleB Offline
Gunslinger

Registered: 11/15/02
Posts: 146
Loc: Clovis, CA,US
Please pardon my ignorance on this subject. But I have a couple of questions. Is it known if this phase reversal is ocurring on the input circuitry of the 950, or the output?
I am curious because I run a 4 satellite, one sub system and have the DVD player set up for all large, with no sub.
I do not use the sub output, I only run 5 analog inputs and let the bass manager in the 950 output any bass below 80Hz to my sub.
So I am not sure yet, if I am getting any 'suck-out' yet from phase reversal. Any comments would be appreciated.

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#45772 - 06/27/03 07:08 PM Re: 6ch anlog input reversed polarity on sub channel
DaleB Offline
Gunslinger

Registered: 11/15/02
Posts: 146
Loc: Clovis, CA,US
One more thing, where is the best source for the Chesky test DVD..still looking, many are sold out.

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#45773 - 06/27/03 07:42 PM Re: 6ch anlog input reversed polarity on sub channel
The Hun Offline
Gunslinger

Registered: 03/14/03
Posts: 59
Loc: Riverside
The Outlaws never officially [or un]admitted to this,as they unable to "reproduce" this phenomonon. My ubderstanding is that it happens on the Sub in or out,so if you don't use that in/output then it won't affect you.

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#45774 - 06/27/03 07:53 PM Re: 6ch anlog input reversed polarity on sub channel
DaleB Offline
Gunslinger

Registered: 11/15/02
Posts: 146
Loc: Clovis, CA,US
Quote:
Originally posted by The Hun:
The Outlaws never officially [or un]admitted to this,as they unable to "reproduce" this phenomonon. My ubderstanding is that it happens on the Sub in or out,so if you don't use that in/output then it won't affect you.



I apologize, my wording was incorrect. I do not use the sub output from the DVD PLAYER to the 950 SUB INPUT. But I do use the 950 SUB OUTPUT!

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#45775 - 06/27/03 08:32 PM Re: 6ch anlog input reversed polarity on sub channel
Kevin C Brown Offline
Desperado

Registered: 12/11/01
Posts: 1054
Loc: Santa Clara, CA
This guy saw it too:

http://www.audioholics.com/productreviews/avhardware/SherbournPT700072100.html

I don't actually think the Outlaws ever tested for it... It's a bugaboo, but there are ways around it.
_________________________
If it's not worth waiting until the last minute to do, then it's not worth doing.

KevinVision 7.1 ... New and Improved !!


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