At what price level will a center speaker improve sound?

T

Terv

Audiophyte
Hello,

We have a small room with only 2 chairs in front of a 50" plasma TV with PSB Image 1B front and rear speakers. I have a PSB Alpha 200C center speaker that just does not seem clear to me. So I have been researching to upgrade my center speaker in the $300-$400 price range.

I read Steve Feinstein's April 2012 article about center channel speaker design.

http://www.audioholics.com/loudspeaker-design/center-channel-designs

Then, I read this 2007 article by Steve Guttenberg.

http://www.cnet.com/news/attention-home-theater-shoppers-think-twice-before-buying-a-center-channel-speaker/


"First things first--center channel speakers do one thing really well--they anchor dialog to the screen for listeners sitting over to the left or right sides of home theaters. So if your family or friends watch movies together, I'd definitely recommend using a center channel speaker.

But for one or two people sitting directly in front of their TV a center isn't necessary, and almost always sounds less good than the left and right speakers. Center speakers tend to sound boxy, so Denzel Washington sounds like he's in a box. Ditch the center and your A/V receiver will redirect the center channel sound over to the left and right speakers. They have the advantage of not being in front of a display, which unfortunately acts like a large reflector behind the center, which messes with the sound. You will of course, need to go in the receiver's speaker setup menu and "turn off" the center channel speaker output to implement the change.

Also, the typical horizontal woofer/tweeter/woofer center design is a flawed concept (three-way center speakers that centrally position the midrange driver under the tweeter are better). In any case, center speakers rarely tonally match the left/right speakers, upsetting the illusion of a seamless soundstage. Yes, the center's responsibilities loom large--on movies the center conveys almost all the dialog, a lot of effects, and some music. That's why all of that will likely sound better over the left/right front speakers. Oh, and it wouldn't be a bad idea to "rechannel" the money you saved by not buying a center speaker into better left/right speakers. That strategy would result in better overall sound."


QUESTION: Since I am not in the high end market would I be better off upgrading my front speakers and not purchasing a center speaker?
 
BoredSysAdmin

BoredSysAdmin

Audioholic Slumlord
before buying new speakers, I'd recommend to looking into fixing room acoustics issues. Not clear human voice reproduction is very often the result of bad acoustics.
Start by posting image of your front setup.
 
j_garcia

j_garcia

Audioholic Jedi
The one you have seems to be relatively capable. I agree that you'll want to look at placement and acoustics first.

If you do have to replace it, you'll need to look at replacing all three front speakers at the same time. It isn't so much the cost as much as finding a speaker that does what you need it to do.
 
Swerd

Swerd

Audioholic Warlord
I would ignore Cnet articles about audio. What that 2007 article said has much right about center channel speakers, and about as much wrong.

You asked two questions. The first was "at what price level will a center channel speaker improve sound?" Let's wait on that for a while because it isn't clear why you have a problem.

Your second question:
Since I am not in the high end market would I be better off upgrading my front speakers and not purchasing a center speaker?
You can answer that right now without spending any money.

Go into your receiver's set up menu, turn off your center channel speaker by telling it you have no center channel speaker. It will redirect that sound to your front left & right speakers. This is sometimes called phantom center channel. Listen while sitting in the middle as well off to each side, and see what you think.

A solution may be as simple as setting the center channel speaker to be a bit louder. Another simple solution would be to move those two chairs a bit (closer together or wider apart, etc.) to see if that improves things.

There was a good AudioHolics article by Gene that addressed this question of just how good or bad is a sideways MTM speaker used in the center? His answer was they aren't that bad as people say. It does depend on how wide a rooms seating arrangement is, and how far away the seating is. Most rooms aren't wide enough for the problem to become big. Sideways MTM speakers as center channels, in my opinion, get a bum rap.
 
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tyhjaarpa

tyhjaarpa

Audioholic Field Marshall
It is best to have matching center to your front speakers. It might be that your placement is the problem, not the speaker itself. I would also try raising the center speaker level from your receiver and see if it has inpact to your sound.
 
S

shadyJ

Speaker of the House
Staff member
The problem with MTMs is the lobing screws up the off-axis horizontal response. The two woofers interfere with each other and creates some strange effects. Here is the horizontal off-axis pattern of a typical MTM that I measured some time ago:

A curious pattern emerges as one listens off-axis here, which should be visible. For comparison, here is a desirable dispersion pattern from a conventional MT design, the Revel M16s:

We see a far more uniform off-axis behavior.
 
DD66000

DD66000

Senior Audioholic
If that PSB Alpha 200C is a straight MTM, turn it on its end, so you have a vertical MTM.....then take a listen...if you hear an improvement, you need a quality center that has the tweeter either above or below the woofer centerline.
Go with the Image C3.
 
H

herbu

Audioholic Samurai
Here is the horizontal off-axis pattern of a typical MTM that I measured some time ago:
Shady, this raises a couple questions to me.
1) What was the distance measured? I wonder how the pattern would change with varying distances.
2) Don't mean to put you on the spot here, but would you consider Centers from Dennis or Salk as "typical"?
 
S

shadyJ

Speaker of the House
Staff member
Shady, this raises a couple questions to me.
1) What was the distance measured? I wonder how the pattern would change with varying distances.
2) Don't mean to put you on the spot here, but would you consider Centers from Dennis or Salk as "typical"?
This was measured at 1 meter. Its an interference pattern that might change with distance, but it would still be there. Dennis and Salk's horizontal MTM's would still suffer from this pattern, although maybe not quite as badly since the tweeter on this speaker was directly between the woofers. Raising the tweeter might help it a little bit, but the main problem is the pressure waves from the horizontally aligned drivers are colliding with each other. That is an unavoidable compromise inherent in the design. The irony is these MTMs can have well-controlled vertical response. Here is that same MTM's vertical response:


It's not great, and there is quite a bit of waist-banding past 30 degrees, but out to 30 degrees it is not bad, certainly better than the horizontal response. The 'listening window' graph of this speaker in this orientation would not be that bad. The problem is the vertical response isn't nearly as important as the horizontal response. This is a speaker that is much better used standing on its side.
 
3db

3db

Audioholic Slumlord
Before we put the cart before the horse and dive too deep into the theory behind MTM, can we get a pic of of the setup from the seating position to see what is going on? I have a PSB Image 8C and a PSB 100C which are both MTM and I have no problems with dialog what's so ever. You can take a look at my pics to see the setup.

I would check the tweeter as well. Remove the grill if possible and place your hand over the tweeter and see if you notice less treble response. If there is no difference in sound between having your hand covering the tweeter and uncovered, then the tweeter maybe dead or on its way out.
 
KenM10759

KenM10759

Audioholic Samurai
I have a KEF R200c center speaker that's W(TM)W and it's great. No issues at all, and even sounds especially good playing MUSIC on the rare day I'm not using 2.1 stereo.
 
KenM10759

KenM10759

Audioholic Samurai
Need to make it not so rare days then. ;) :D
Nah...5.1 has it's place and time and choice of music, I just prefer the imaging I get with 2.1 most times. Much of that time I can put my receiver into its "analog bypass" mode and it's feeding just the L-R mains, no sub and capable of handling the appropriate type of music.

But thanks for the suggestion. Point taken.
 
H

herbu

Audioholic Samurai
This was measured at 1 meter. Its an interference pattern that might change with distance, but it would still be there.
For this attribute, I'm thinking 3 meters would be more appropriate as an indication of whether it will matter in real life. I understand the theory and it makes sense. Just not convinced it matters.
 
S

shadyJ

Speaker of the House
Staff member
For this attribute, I'm thinking 3 meters would be more appropriate as an indication of whether it will matter in real life. I understand the theory and it makes sense. Just not convinced it matters.
The dispersion pattern would mostly stay the same whatever distance you measured from, although it might shift in frequency. And it absolutely does matter. This is one of the cornerstones of Floyd Toole and the NRC's work. A uniform off-axis response is very important for what is considered a 'good sound' in normal room acoustics. There is a boatload of research behind this.
 
Swerd

Swerd

Audioholic Warlord
The dispersion pattern would mostly stay the same whatever distance you measured from, although it might shift in frequency.
The dispersion pattern does shift with the frequency of the sound. It depends entirely on the distance between the two mid woofers. Think of that distance as a wavelength, rather than inches.

Regardless of the sound's wavelength or the distance between the mid woofers, a listener in the center will hear sound from both in phase with each other. As listeners sit more off center, up to about 30° off center, sound from the two mid woofers may or may not arrive at the listeners out of phase with each other, causing destructive interference. Just how much depends on wavelength of the sound, the listeners sitting distance and how far off center they are. So there are no absolutes here.

For voice and movie soundtrack dialog, sideways MTM speakers work surprisingly well in many rooms, despite everyone's warnings.
This is one of the cornerstones of Floyd Toole and the NRC's work. A uniform off-axis response is very important for what is considered a 'good sound' in normal room acoustics. There is a boatload of research behind this.
If I remember correctly, Toole meant that uniform off-axis response was important for loudspeakers in general, and not specifically about center channel speakers reproducing voice in a surround system.
 
3db

3db

Audioholic Slumlord
The dispersion pattern would mostly stay the same whatever distance you measured from, although it might shift in frequency. And it absolutely does matter. This is one of the cornerstones of Floyd Toole and the NRC's work. A uniform off-axis response is very important for what is considered a 'good sound' in normal room acoustics. There is a boatload of research behind this.
You are still putting the cart before the horse. Lets see a pic of his layout. Like I said before, I have no problems hearing dialog from both of my two center channels in my two setups, one of which has a seating position greater than 30 degrees off center.
 
S

shadyJ

Speaker of the House
Staff member
For all the complaints we get in these forums about dialogue intelligibility, I don't think that horizontal MTMs do work well. It is a compromised design, and I bet we would get a lot less complaints with something that had a good off-axis response. I think a uniform off-axis response is important for the center; consider how much speech is in the woofer's frequency range. The typical crossover point for a two-way mtm will be around 2.5 kHz or so. A three-way can alleviate that somewhat, at least if the tweeter and mid are vertically aligned. And even for those seated directly in front of the center, consider how much sound we hear is still reflected sound.

Anecdotes about how well dialogue is heard in X setup is irrelevant. Let's see a frequency response measurement of the center at various listening positions.
 
3db

3db

Audioholic Slumlord
Anecdotes about how well dialogue is heard in X setup is irrelevant. Let's see a frequency response measurement of the center at various listening positions.
Lets see the user's setup first. Why don't you get the whole picture before going off on theoretical tirade? As far as anecdotes go.. I don't claim I wouldn't hear differences. I'm saying I have no problems hearing mine what so ever so they must be doing something right. :rolleyes:
 
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