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post #1 of 18 Old 07-28-2012, 10:19 AM - Thread Starter
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I was just curious on how people felt about not having a center speaker.

I have a pair of JBL 4312's. And some nice in ceiling surrounds. I am planning on getting me JBL's re conned and checked and. But I do not have a third one for a center... What do you guys think?
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post #2 of 18 Old 07-28-2012, 10:38 AM
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Quote:
Originally Posted by N3kKo View Post

I was just curious on how people felt about not having a center speaker.
I have a pair of JBL 4312's. And some nice in ceiling surrounds. I am planning on getting me JBL's re conned and checked and. But I do not have a third one for a center... What do you guys think?

Not having a center channel speaker basically means that you are depending the creation of what has long been called "The Phantom Center Channel". This is the central stereo image that is a result of how the recording is mixed. It is strongly influenced by the contents of the main channels that are identical in both main channels.

The strength and coherency of the "Phantom Center Channel" is highly dependent on your setup, where you sit, and the recording. I personally find this works well for me as I listen to both music and movies on a 2.1 system.

YMMV!
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post #3 of 18 Old 07-28-2012, 02:46 PM
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Arny, do you encounter any discernible HRTF "2K dip" from down-mixed CC material? I'm not sure if it was in his newest book, but I'm pretty sure I read, and it makes perfect sense, that there's a HRTF 2K dip caused from this. I've never performed the test, I believe it, I'm not convinced how significant it is. Most important for me is the "anchoring" of CC material.

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post #4 of 18 Old 07-28-2012, 05:30 PM
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Originally Posted by FOH View Post

Arny, do you encounter any discernible HRTF "2K dip" from down-mixed CC material? I'm not sure if it was in his newest book, but I'm pretty sure I read, and it makes perfect sense, that there's a HRTF 2K dip caused from this. I've never performed the test, I believe it, I'm not convinced how significant it is. Most important for me is the "anchoring" of CC material.

Since I fine-tuned my system's equalizer by ear it sounds fine to me at 2 KHz. Go figure!
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post #5 of 18 Old 07-29-2012, 04:42 AM
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The problem with a phantom center is one of practicality. To get a palpable phantom center you have to have a symmetrical floor plan with symmetrical acoustic properties and speaker positions and have the listener positioned on a line centered exactly between them. In most rooms this means a single seat, an even a small shift of the heads position causes the phantom center to skew. Not to say it can't work, but it's really very touchy. For examplr, having slightly different acoustic properties on one side of the room makes the phantom center less defined ands blurry. A good two-channel room demands far more attention to early reflections and acoustics in general. But this is hardly ever done. As a result, very few people have ever heard good two channel stereo. A center speaker locks the center channel to a position in the room that is independent of seat position, much less head position, and makes the necessity of a perfectly symmetrical floor plan and acoustics much less important. It's possible to have a really decent 5.1 room with minimal acoustic treatment.

Speaking strictly of 5.1 material, the center channel carries somewhere around 80% of the total acoustic power averaged over the entire length of the program. Close to 100% of dialog and on-screen sound effects are in the center channel only.

Reprocessing a stereo mix to even 3 channels (LCR) is a bit of a pain though. There is no single process that can be used for every recording, and what's available for this in the typical AVR runs the range from very good to unacceptable. This is partly because stereo mixes were never expected to be up-mixed to more channels, so there can be no even partly standardized method for doing so. Rooms used for mixing and mastering stereo material have never followed any particular standards either as to speaker position, which strongly affects how the phantom center is presented during the creative process. Fortunately even simple AVRs usually have a 2 channel stereo mode that can be used when you want to play two speakers only.

Down-mixing 5.1 to stereo is easier, and may even have been taken into account during production. 5.1 mixing rooms, particularly film dubbing stages, are highly standardized because the layout of the expected playback systems are also standardized. There are settings within the 5.1 encoder that deal specifically and predictably with stereo down-mix, and depending on the target the material the stereo down mix may even have been carefully checked. But not always. It's unfortunately not that unusual to find a 5.1 track that doesn't play well in stereo.

I always advocate a center speaker unless the owner is a hard and fast stereo only person, at which point the entire room design is affected by his application.

A footnote here: the concept of a special "center channel speaker" that is in some way different from L and R is driven only by aesthetics. From the standpoint of sound, the center should be identical to L and R in every way. True, the position of the center in the room will by nature impress a different signature on it, but unless the speaker starts with the same "voice" as L and R there's little hope of presenting a unified and believable LCR sound field. Manufacturers that provide the ubiquitous horizontally oriented center are doing it becaus the market demands it. A tall vertical center speaker is difficult to accept visually and may be impractical physically, but the sonic results are unmatched.
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post #6 of 18 Old 07-29-2012, 07:02 AM
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Originally Posted by has7738 View Post

The problem with a phantom center is one of practicality.

Your expansion of my comment that the effectiveness of phantom center channels is a "YMMV" issue raises the same points I had in mind with my brief reply. Thanks!

However, I think that the problems that are common with real center channel speakers were understated. The difficulties of phantom center6 seemed overstated.

For one thing the timbre matching of the phantom channel is inherently close to ideal since it involves the identical same speakers,identical same room features and identical same ears as the main speakers which are always there and dominant.

Phantom center channels are still acceptable to very many 2-channel loving audiophiles.

My own biases in the matter is that audiophiles seem to tend to expect a far more detailed and well-defined phantom center than exists for most seats at most live performances, and not by a little. Since most give at least lip service to the idea that live performances are the ultimate standard, this indicates to me that some tolerance can be given without burning one's music lover card. ;-)

Creating a sweet spot with just two speakers that does not require a fixed head clamp to enjoy is far from being impossible.
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post #7 of 18 Old 07-29-2012, 09:03 AM
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Quote:
Originally Posted by arnyk View Post

Your expansion of my comment that the effectiveness of phantom center channels is a "YMMV" issue raises the same points I had in mind with my brief reply. Thanks!
However, I think that the problems that are common with real center channel speakers were understated. The difficulties of phantom center6 seemed overstated.
For one thing the timbre matching of the phantom channel is inherently close to ideal since it involves the identical same speakers,identical same room features and identical same ears as the main speakers which are always there and dominant.
Agreed. It's one aspect where the phantom has a leg up.
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Phantom center channels are still acceptable to very many 2-channel loving audiophiles.
Again, agreed, but I think a large part of that is driven by the overwhelming catalog of 2-channel stereo, and the assumption that accurate reproduction of a sound field can be achieved by two sources in a small room. Just not so. The configuration of the reproducing system is completely different from the configuration of the original sound producing elements, and simply can't replicate the original sound field. In fact, very early research into stereo sound recording and reproduction by Bell Labs concluded more channels/speakers was always better, and that the absolute minimum number of speakers/channels necessary for a reasonable stereo soundstage was 3, Left, Center and Right. We ended up with 2 because of the difficulty of placing 3 discrete channels into a release medium.
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My own biases in the matter is that audiophiles seem to tend to expect a far more detailed and well-defined phantom center than exists for most seats at most live performances, and not by a little. Since most give at least lip service to the idea that live performances are the ultimate standard, this indicates to me that some tolerance can be given without burning one's music lover card. ;-)
Creating a sweet spot with just two speakers that does not require a fixed head clamp to enjoy is far from being impossible.

Problem with the "sweet spot" is, if you want it to be a full-bandwidth sweet spot with solid and dimensional phantom center, you have apply unusual early reflection control. The hearing mechanism is quite sensitive to tiny timing errors, and above 3KHz inches do matter a lot. If you don't mind a phantom center that anchors well below 3KHz, the sweet spot isn't too tight. But to really make it palpable you have to be in a very tight window, and very equidistant to the speakers.

I had a client that was proud of his two-channel stereo setup. He had some rather esoteric gear, and some respectable high-end speakers. But the left channel was within about 3' of an untreated wall, and the right was the same distance from a window with heavy drapes. We listened to a female vocal recording, and I asked him if the smeary center image bothered him. He never noticed it. I placed a spare piece of Sonex foam on the left wall so that it would absorb the first reflection, and the vocalist suddenly popped right into the room, was so dimensional that we could have patted her on the head. Of course, off the center line even a little, and that fell apart. Treating the early (and asymmetrical) reflection was the key.

Consider this: if spacial hearing can localize forward images to angles under 5 degrees, how could it be possible to have a solid center image even a few inches off the center line? The skew in inter-aural timing is enough to smear the image, though obviously that mechanism is frequency dependent.

Some might be completely satisfied with how it works, and be completely happy with ignoring the difference between the sweet spot and the relatively collapsed center image you get out of the sweet spot. But the reality is, you won't get a solid palpable full bandwidth phantom center anywhere but a very well positioned sweet spot in a space that has at least some critical acoustic treatment.

On the multi-channel side, the principle is: if you want a sound to come from there, put a speaker there. You minimize the demands of phantom images, and the listening sweet spot becomes enormous. Then with proper treatment, tambre matching the center becomes a non-issue. The big problem with a multi-channel setup is the lack of audio only recorded material.
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post #8 of 18 Old 07-29-2012, 09:40 AM
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I was running without a center for a while in our basement system. Had a pair of Paradigm Atoms for the mains. It was kind of neat how it seemed like there was a center, even though there wasn't. I still like our setup much better with the CC-190 that I added, though. You tend to get more ambiance out of the mains, because they don't have to handle the center channel audio at the same time.
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post #9 of 18 Old 07-31-2012, 09:56 AM
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I think "YMMV" is the best response to the OP. Without details of the physical set up, it is hard to answer the question. There is theory, then there is practice. Experimentation is easy enough. Most AV systems let you choose no CENTER quite easily.

I am in no way an expert here, but this thread caught my attention since I have had the same quesion for my own system, but have not have had the chance to experiment yet.

For my great room setup, TV and speaker locations are dictated by other factors, the wife and furnishings in the room. The house is a chalet with a 25' to the peak ceiling, wood panel walls, exposed beam wood ceiling and a wall of wndows. The 60" TV is in a corner and the seating is an L shaped leather sectional dividing the room in half. My "ideal" seat is in the corner of the sectional. Measured distance to the screen is ~12 feet. Def Tech BP2004 fronts are on either side of the TV pulled forward about 4" (until the wife realizes and tries to push them back.) The Center speaker is a 5-1/4" MTM Waferdale sitting about 10-12" below the screen on the top shelf of the TV stand.

The Def Tech speakers are better quality than the Center speaker (which is surprisingly good). Separation of the Fronts is about 6 feet. Imaging in 2.0 of the BP speakers is fairly wide. So my guess is, when in the corner of the sectional sofa, 13' from each speaker, the system may sound better without a Center speaker because of the better quality of center programming from the better speakers. ( I assume the decoder will send Center channel programming to the Fronts.)

Now that I wrote all of this, I am anxious to test this out tonight. I am interested in any predictions and will post my SUBJECTIVE results soon.
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post #10 of 18 Old 08-01-2012, 05:10 PM - Thread Starter
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I have my system hooked up now, jbl 4312 in the front, Polk audio 8' cieling speakers, a Sony Str-db830, and a BIC sub. I put on a blu ray in my ps3 and went to the audio settings. It only shows PCM 48 kHZ on the ps3 and receiver. I can't really hear my rear speakers.. The test tone works great with them though..
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post #11 of 18 Old 08-01-2012, 05:17 PM - Thread Starter
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I have my fronts ran to the receivers left and right front, my rears hooked to the receivers rear surround left and right, and my sub connected to the sub input.

Also I have my center set to off. And I turn the mode to Normal Surround.
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post #12 of 18 Old 08-01-2012, 05:50 PM - Thread Starter
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The way I am getting sound is through an optical cable plugged into my TV. All of my devices are plugged in to my TV with HDMI. And my TV is connected to my recover with optical.

So my PS3 is connected to my TV via HDMI and my receiver is receiving audio via an Optical cable from my TV to it.
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post #13 of 18 Old 08-01-2012, 07:11 PM
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Connect the rear speakers to the side surround terminals, not the rear surround.


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post #14 of 18 Old 08-01-2012, 07:30 PM - Thread Starter
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post #15 of 18 Old 08-02-2012, 05:58 AM
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Quote:

You seem to have a 5.1 receiver, so of course the only surround speakers are rear surrounds.

So much for Kal's advice which is usually very good.
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post #16 of 18 Old 08-02-2012, 06:02 AM
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Quote:
Originally Posted by N3kKo View Post

I have my system hooked up now, jbl 4312 in the front, Polk audio 8' cieling speakers, a Sony Str-db830, and a BIC sub. I put on a blu ray in my ps3 and went to the audio settings. It only shows PCM 48 kHZ on the ps3 and receiver. I can't really hear my rear speakers.. The test tone works great with them though..

Exactly how much comes out of the surround speakers depends a great deal on the source material.

Once you've turned the fronts+center way down, and turned the surrounds way up, its pretty much out of your hands.

Every AVR seems to have its own "sound field" settings that may affect this.
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post #17 of 18 Old 08-08-2012, 06:18 AM
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late to teh party here, but is there any processing that changes 5.1 to 4.1 material?
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post #18 of 18 Old 08-08-2012, 11:55 AM
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Hi Kimwyn,

Changing 5.1 to 4.1 simply involves taking the audio from the center channel and mixing it in to the left and the right channel. To keep the volume correct, half of the signal is mixed into each side channel.

Most AVRs (maybe all) will do this correctly, if you configure them for no center speaker.
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