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#45746 - 03/16/03 10:47 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
There was a data point in HTF too. Dude with a Denon 3802 or 3803, added an ICBM. He actually found the same thing. Signal to the sub was "out of phase" between the digital crossover in the receiver vs the ICBM.

Yeah, you can move the sub around, but that's not practical. If the 950 did have a distance (delay) setting to the sub, that's where the solution would lie. Or even a setting in the 950's software for polarity to the sub (my Sony TA-E9000ES had this).
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#45747 - 03/19/03 11:56 AM Re: 6ch anlog input reversed polarity on sub channel
surroundophile Offline
Gunslinger

Registered: 05/02/02
Posts: 68
Loc: Chicago, Il. USA
Quote:
Originally posted by bossobass:

when in digital modes, you have digital delay settings to time align the satellites (all 5 speakers). when you switch to analog, you lose the delay, causing different arrival times of satellite/redirected bass sound.

this means that the out-of-phase adjustment will be different in every setup.

if someone were so inclined to move their sub to a position that's equidistant with the mains, use 80hz for digital HP and test for phase that way, it might verify that it ain't the crossover. you would not be testing the best bass, but rather the phase difference between digital and analog modes.

in other words, i suspect that this problem isn't unique to the 950. phase is time. very few people place their subs with time/distance in mind, and every setup is different in that respect.

just a view from the peanut gallery.

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#45748 - 03/19/03 12:10 PM Re: 6ch anlog input reversed polarity on sub channel
surroundophile Offline
Gunslinger

Registered: 05/02/02
Posts: 68
Loc: Chicago, Il. USA
Quote:
Originally posted by bossobass:


if KCB had said his test revealed a 180 degree shift, i would lean toward the analog crossover as the problem and the switch flipping cure.

the 'possible' scenario i offered IS electrical (with delay, without delay)...not placement...as the problem. placement is a way to test the theory.

in repeating kevin's test, i found the phase difference (less difference than kevin's). i have 2 subs. i placed them equidistant with the front 3 speakers and the difference was reduced.

anyone is free to tell me why that is.


Sorry about the double post.

Haven't been here for a while due to looking for work (was laid off in Oct...still looking)

I think Bossobase DOES have the right idea here. When this "problem" originally was reported by KCB, I took the Chesky test DVD-A, and compared the DVD-A tracks (using the 6CH analog pass-throughs with bass summing on), to the Dolby Digital tracks using the 950's decoder and found NO phase difference.
KCB subsequently got the Chesky disc, did the same test, and STILL got a phase difference. I just went back last night ans checked it again, and still have NO PHASE DIFFERENCE.
I have all my speakers set at the same distance in the 950. In my player, I have all the speakers set to the same distance, EXCEPT the subwoofer, which is closer than all the other speakers (the player, a Pioneer DV47ai a sub distance whereas the 950 doesn't). Maybe this is why I DON'T have a phase difference.
Outlaws/Scott, could you please clear this up for us?
If there is a problem, it could be fixed at the same time as the DTS-ES problem.

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#45749 - 03/19/03 03:21 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
The 47ai's sub distance setting only has an effect on the LFE channel, but *not* the info that the 950's analog crossover crosses over from the mains to the sub.

[Edited:] You do have all small speakers in the 950, sub "on" (all large in the player), and the 80 Hz analog crossover switch on the 950 "on", right? (You have to make sure to be using both the digital and analog crossover, repectively, when you do the test.)

[This message has been edited by Kevin C Brown (edited March 19, 2003).]
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#45750 - 03/20/03 09:17 AM Re: 6ch anlog input reversed polarity on sub channel
surroundophile Offline
Gunslinger

Registered: 05/02/02
Posts: 68
Loc: Chicago, Il. USA
Quote:
Originally posted by Kevin C Brown:
The 47ai's sub distance setting only has an effect on the LFE channel, but *not* the info that the 950's analog crossover crosses over from the mains to the sub.

[Edited:] You do have all small speakers in the 950, sub "on" (all large in the player), and the 80 Hz analog crossover switch on the 950 "on", right? (You have to make sure to be using both the digital and analog crossover, repectively, when you do the test.)

[This message has been edited by Kevin C Brown (edited March 19, 2003).]


Yes, all 950 speakers set to small, analog bass management switch set to on, and distances set the same all speakers (which they physically are).
DV47ai all speakers set to large, and all speaker distance set the same except the subwoofer, which is physically much closer.

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#45751 - 03/20/03 10:38 AM Re: 6ch anlog input reversed polarity on sub channel
bossobass Offline
Desperado

Registered: 08/19/02
Posts: 430
Loc: charlotte, nc usa
surroundophile's last post adds fuel to my theory.

he doesn't see the phase shift between analog and digital because his speakers are equidistant from the listening position.

this means that there is no time-arrival difference between the 2 modes of redirected bass to the sub.

the digital delay settings use the front speakers as a zero point, regardless of what distance you select. from that reference point, the delay is added to the difference of the closer speakers.

surroundophile (and anyone who has all sats placed equidistant) actually has no digital delay applied to his system, therefore, no difference when switching to 6 ch bypass.

as far as the ICBM using a 2nd order low pass, i don't understand the logic of that at all. that slope would not match anything in BM mode. OTOH, if using vented mains, the 6th order LP is correct.

if you have, say, vented mains, and you selected the 2nd order LP, you would have a 12DB/octave slope on your sub and a 36DB/octave slope on your mains (vented roll-off of 24DB/oct + 12DB/oct HP applied = 36DB/oct). this, plus the unknown Q of the HP filter and how it reacts to the vented mains, would likely cause a hump at crossover, which would have nothing to do with phase.

also note, the ICBM manual claims less than 1 degree phase shift at crossover.

someone needs to design a delay system that sets the SUB as the zero point and is analog, after D/A, and thus a set-it-and-leave-it system (or...maybe someone already has )
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#45752 - 03/20/03 10:45 AM Re: 6ch anlog input reversed polarity on sub channel
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
the digital delay settings use the front speakers as a zero point, regardless of what distance you select. from that reference point, the delay is added to the difference of the closer speakers.


Hmmm. If I were the implementor I'd use the furthest speaker as zero and compensate the others. Are you certain the fronts are hardwired as the zero point, or does it just happen to work that way often? It seems the surrounds could often be furthest on bigger rooms.
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#45753 - 03/20/03 01:18 PM Re: 6ch anlog input reversed polarity on sub channel
bossobass Offline
Desperado

Registered: 08/19/02
Posts: 430
Loc: charlotte, nc usa
Quote:
Originally posted by charlie:
Hmmm. If I were the implementor I'd use the furthest speaker as zero and compensate the others. Are you certain the fronts are hardwired as the zero point, or does it just happen to work that way often? It seems the surrounds could often be furthest on bigger rooms.


i suspect that you are correct...the largest number is the zero point. i should have been more specific.

unfortunately, there is little in the way of specs that explain how digital delay is set up on pre/pros.

i wonder why the sub isn't included in the delay setup? it's 'usually' the farthest speaker. it still wouldn't solve the switch to analog, where no delay is offered.
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#45754 - 03/20/03 01:28 PM Re: 6ch anlog input reversed polarity on sub channel
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
There are some DSP boxes out with VERY configurable processing for pro (AES/EBU ?) digital connections - I'm hoping that once the consumer digital audio connection is finally standardized we as consumers start to see similar devices for that data-stream.

In that case analog processing could be finally obsoleted for most applications.
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#45755 - 03/21/03 12:27 AM Re: 6ch anlog input reversed polarity on sub channel
Kevin C Brown Offline
Desperado

Registered: 12/11/01
Posts: 1054
Loc: Santa Clara, CA
BoB- I'm not buying it.

The reason why, is that my sub is immediately to the left of my left main speaker. The left and right's themselves are identical distances from my listening position. (About 8 ft for the mains, and maybe 9.5 for my sub.) 1.5 ft isn't enough to explain the difference I get. At 80 Hz, it would have to be about 6.8 ft or so. (1/2 the 80 Hz wavelength.)

Plus, the test disc is a DVD-A disc, which the player *does* do time alignment for anyway. So time alignment is being done in the player for DVD-A, and in the 950 for CD/DD/DTS. I still get the phase difference. Distances in the 950 are set identically to the player (except for the sub, which the 950 doesn't have).

OK, but now that I think about it, here's a question: I use the variable knob phase control on my sub to dial in the "phase" (i.e., time alignment) for DD/CD/DTS because the 950 does not have a distance setting for the sub. So maybe in the player, I should set the distance to the mains and sub as the same? (Because it's already compensated for?) *That* makes sense, but again the problem is that I only have 1 ft difference in the player for the mains and sub distance.

??
_________________________
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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