The Problem with Many Center Channel Speakers (by Erin)

[valerianf]

Phantom center - Wikipedia

en.m.wikipedia.org

 

[Sancus]

Phantom center - Wikipedia

en.m.wikipedia.org

I know what phantom center is. If you have a physical center, phantom center is not relevant because most material is played by the physical center by itself. Not spread to the L/R.

This thing you described as: "The FL and FR speakers will create a phantom center speaker that will play at the same time as the physical center speaker." is not a real issue because phantom center is almost never used in film/tv multichannel content.

When you "tell" your AVR that there is no center speaker, doesn't it take the center information and divide it between the L/R?

Sure, but that's not what the poster described. They said they have a center, it's just set to small. Setting a center to small does not produce a phantom center for anything. Low frequencies do not produce a phantom center at all.

My car is not standard from manufacturer but modified to get some workaround about the design issues.
Every user has different requirements.

I don't see the relevance. What you personally prefer in your room is not useful or appropriate advice to give other people, especially not when it deviates from what's actually in the literature. If you want to say "well I like x better even though it contradicts the spec" that's fine but you can't expect anyone to take you seriously if you do that.

 

[Everett T]

I noticed the Polk crosses over at 260 Hz (5 ¼" mid) and the Monitor Audio crosses at 650 Hz (3" mid). KEF R2C crosses at 400 Hz. Revel C426Be crosses at 210 Hz while the Revel C208 crosses at 375 Hz. Not sure if that means anything but it seems that the "better" speakers might be pushing the crossover from the mid to the woofer as low as possible. Which makes me wonder about the Monitor Audio a bit. The ELAC Uni-Fi 2.0 center crosses at 200 Hz, and, for $370 seemed to have pretty good response and dispersion. Maybe pushing the limits of a 3-way design though.

You typically want the transition above around 400hz and up, unless you have an exceptional midwoofer.

 

[Aerith Gainsborough]

So basically: most center speaker designs fail hilariously at their primary jobs: providing a good and even sound for the side seats.

Personally, I'm stuck with 4.1 due to space constraints (no where to put a center) which isn't much of a problem as a single listener but this is very interesting data nonetheless.

 

[SynthesisCinema]

Would be nice to see how TMM would do against MTM. Example M&K LCR750C. Any views?

 

[alex-z]

Would be nice to see how TMM would do against MTM. Example M&K LCR750C. Any views?

That depends on the crossover design. If it is a 2 way design, it is worse than the MTM configuration, because now the horizontal off-axis response is still poor, but also asymmetrical. A 2.5 way or 3 way design would improve performance significantly.

Looking at the LCR750C spec sheet, it is a 2 way design. I would avoid it.

 

[ooheadsoo]

That depends on the crossover design. If it is a 2 way design, it is worse than the MTM configuration, because now the horizontal off-axis response is still poor, but also asymmetrical. A 2.5 way or 3 way design would improve performance significantly.

Looking at the LCR750C spec sheet, it is a 2 way design. I would avoid it.

Who does a TMM 2 way?

 

[DonH56]

Who does a TMM 2 way?

Look up a couple of posts...

 

[ooheadsoo]

Look up a couple of posts...

When output trumps fidelity...

 

[bmoliver]

Yes, but an R3 is a bad example since it’s a coaxial already. A normal 2-way bookshelf would do just fine. Don’t put it in it’s size though (you can wij the R3)

Would the same apply to using an older Boston Acoustics HD5 bookshelf speaker, as I have several of these hanging around? I have been using a custom made center channel with a vintage Jordon Watts driver plus vintage Peerless tweeter (model 810065). My left/right channels are also custom made base reflex boxes with 2 Jordon Watts + vintage Philips dome tweeter each. Also, is the Polk T30 similar to the Polk XT30 in radiation pattern?

 

[Cousin Mose]

The center doesn't need to cover most dialog though, it needs to cover *all* possible dialog frequencies including overtones. The standard ranges for speech intelligibility go up to 8khz(which is why that's the max audiologists test for hearing), and down to 125hz. Unfortunately, even that is not enough, Barry White has a median vocal frequency of 71hz and it's normal, if less common, for men to have frequencies under 100hz. And then there's also voices altered by computer, which are quite common in many genres, that could be just about anywhere.

That's ignoring the foley issue mentioned by the poster above, where sound effects are also primarily in the center. In general, the Dolby/DTS/etc specs expect and treat the center as a full range speaker that is identical to the L/R. So anything else is out of spec and substandard.

What if instead of a full-range center, is was a 1-way midrange speaker that only covered the "normal" speech range (let's say 80Hz to 300Hz), and we used signal processing to send the higher frequencies to the L-R channels, where they can be reproduced with the phantom center effect? Basically, a half-phantom, half-real center channel. A single 6.5" driver in the center should have no problem handling this range. Anything below about 80Hz can be handled by the sub, since it is going to be nondirectional in residential rooms anyway. The phantom effect may be good enough for the high frequencies when paired with a real center that is doing the heavy lifting.

Thoughts? Would this be the best of both worlds, or the worst of both worlds?

 

[norman bates]

hmmm.

I think 1-4khz is needed.
Hearing aids often boost this range to help hearing.

As is 8khz for the s's and t's that help with intelligibility.....


I could be wrong.

 

[Head_Unit]

If anyone remembers Tom Nousaine (RIP)

Oh yes! RIP indeed. He wrote a couple of seminal pieces, one on box stuffing I think.

 

[Sancus]

What if instead of a full-range center, is was a 1-way midrange speaker that only covered the "normal" speech range (let's say 80Hz to 300Hz), and we used signal processing to send the higher frequencies to the L-R channels, where they can be reproduced with the phantom center effect? Basically, a half-phantom, half-real center channel. A single 6.5" driver in the center should have no problem handling this range. Anything below about 80Hz can be handled by the sub, since it is going to be nondirectional in residential rooms anyway. The phantom effect may be good enough for the high frequencies when paired with a real center that is doing the heavy lifting.

Thoughts? Would this be the best of both worlds, or the worst of both worlds?

Research has shown pretty conclusively that phantom center sounds worse than a center channer, and slicing up the overtones of vocals like this just sounds like asking for trouble to me. Not to mention, all surround content is mixed and mastered with a center that meets spec. So you're adding another, very strange variable to the playback system.

IMO you should get a good center, or skip the center entirely. It's honestly just not that hard to make room for a decent 3-way center with at least 6.5" woofers.

 

[restorer-john]

Research has shown pretty conclusively that phantom center sounds worse than a center channer

Can you cite that specific research? (genuinely interested)

 

[norman bates]

what about head related transfer function ?

To me, listening to a movie without a center, wouldn't you get a dip at 2khz ?
Maybe the processor already boosts this range, idk.

When I made an ambio barrier and had the speakers touching side to side, voice was right there.
MOve the speakers 6' apart, no barrier, sitting 12' away, it was a hazy 3' wide blob maybe 6db down.

see post 736 (crosstalk dip from stereo speakers)

KEF R3 Speaker Review

I've been taught a few dB lacking in that area give the impression that the singer is in the back of the scene, whereas a few dB too much give the impression he is in the front. Did you have such an impression? Precisely. In fact, looking back at my review from almost a year ago I wrote...

www.audiosciencereview.com

someone else later mentions that it is already mixed in to sound right (adding the boost there) for stereo recordings to get around crosstalk.

 

[jsilvela]

On the discussion of phantom center vs. real center. In my opinion/experience it's not just about the FR. Toole's book comments that the stereo dip is not very noticeable in average living rooms with average reflections/reverb. Apparently very noticeable in studio environments with low reverb.

But A/B testing phantom vs real center, I notice:
- the phantom image is a lot less localized. Vocals have a "voice of god" feel that I like less than a real center (YMMV etc.)
- if I let a movie just roll without "listening critically", I find the dialog more intelligible with a real center. Not a night-and-day difference though

I'm a convert to center. For a while I used a third bookshelf speaker on a speaker stand as a center speaker.
Recently I got a horizontal design as I had room under the TV. I was very careful choosing it, avoiding the dispersion issue of most MTM designs.

One thing I keep hearing does not mesh with my experience: "the center speaker is the most important / needs to be the best speaker".
I'm no connoisseur, but even using a center that was not better than the L/R mains, I still preferred it over phantom center.

 

[Spkrdctr]

On the discussion of phantom center vs. real center. In my opinion/experience it's not just about the FR. Toole's book comments that the stereo dip is not very noticeable in average living rooms with average reflections/reverb. Apparently very noticeable in studio environments with low reverb.

But A/B testing phantom vs real center, I notice:
- the phantom image is a lot less localized. Vocals have a "voice of god" feel that I like less than a real center (YMMV etc.)
- if I let a movie just roll without "listening critically", I find the dialog more intelligible with a real center. Not a night-and-day difference though

I'm a convert to center. For a while I used a third bookshelf speaker on a speaker stand as a center speaker.
Recently I got a horizontal design as I had room under the TV. I was very careful choosing it, avoiding the dispersion issue of most MTM designs.

One thing I keep hearing does not mesh with my experience: "the center speaker is the most important / needs to be the best speaker".
I'm no connoisseur, but even using a center that was not better than the L/R mains, I still preferred it over phantom center.

A LOT of the conventional wisdoms that have come into being in the last 40 years are bogus. Having all your speakers being the same brand and type, having to have ATMOS (which is good if you can) phantom centers are better than real centers etc. are bogus. Atmos, if you can fit it into your system speaker wise is great but if not your surround system will still be very nice. The lack of a center does not anchor the dialog and it does seem more to put the voices into a big area. Really, most all audio is kind of a try it and see affair. Whatever you find you like is fine!

 

[Iarwa1N]

In light of this video I am torn between Kef Q650C and SVS Ultra Center. Both of them costs the same (799+tax). I couldn’t find any review comparing these. Can someone help me?

 

[Ricardojoa]

The most important aspect of a center speaker is the location. Once the dialogue comes from the center of the screen, all else becomes less important.