A Better Center Channel?

[Paul R]

Our,video sound runs through our living room two channel setup. Increasingly, over me past year, Karen and I what've notices that dialog, while perfectly placed, is getting lost in overwhelming music tracks. This is much more noticeable with newer material on BR, and with Dolby Digital tracks from Netflix.

 

My solution today was to take a pair of PSB Imagine B's, and wire them in mono to the center channel. They are placed to either side of the television, slightly behind and inside the PSB Synchrony 1Bs, angled in a 35 degrees.

 

Obviously, I lifted this idea from Magnepan, but boy, it is sure working well. We have never found a center channel speaker we we're happy with before, but this seems to stand a good change of working. Anyway, I was wondering if anyone else has done this and if so, what was the best positioning and angle you came up with for making thing work as best they'd possibly can. Should the center channels be higher or lower than the main music speakers?

 

Opinions welcome.

 

Paul

[wgscott]

What's the advantage of two speakers? Do they just play louder because the resistance is halved, or is it doing something else?

 

I was sort of doing this with two Orb speakers, but I recently replaced those two center-channel speakers with a single B&W M1. They were both pointed straight forward and centered under the TV. The single M1 sounds better. Maybe I should get another.

 

I think cabal TV and maybe netflix over-emphasize the bass either due to compression or just as some ill-considered policy. It is especially apparent on older British TV shows, but even Clone Wars seems to have a huge bass component.

[mayhem13]

Question is, how did you wire them?.....in series?.....or parallel?

[coxhaus]

Hopefully those are 8 ohms speakers so you are not feeding your amp 2 ohms loads. I think the center channel speak does most of the work for TV and movies and you really need a good center channel speaker.

[Kal Rubinson]

The big issue with pairs of center channel speakers is that their inevitable separation results in a "Venetian blind" irregular radiation in the plane of the separation. Thus, speakers on each side of the display would have irregular radiation, due to alternate beams of reinforcement and cancellation in the horizontal plane. It would be less significant in the vertical plane. A well-designed single speaker would be superior.

[sdolezalek]

Paul: As the first Magnepan tri-center customer, I am admittedly a strong fan of that approach. Although I see the logic of Kal Rubinson's response, I personally started with just a Magnepan CCR center channel (and I believe it is as good a center channel as you can buy), but there is no question in my mind that the tri-center is superior. Now as to why:

 

1. Possibly because the overall radiating area of the CCR plus two MCC2's is closer to that of a 20.1 and thus mates better (could be, but see point 3 below);

2. Possibly because the two speakers on each side of the television do create a unique radiating pattern that somehow actually works (although I'd be inclined to agree with Kal on his point);

3. Possibly because in adding the center and the sides, I programmed a slight delay into the pre-pro that makes the sides a bit of an echo of the center and possibly because of the unique radiating pattern of the Maggies themselves.

 

I have not seen any scientific or hearing-oriented work that proves or disproves the effect, but I do know that Magnepan regularly gets listeners to prefer the tri-center in A/B blind testing. For me, the biggest difference was a sense that the dialog was suddenly "in the room" rather than coming from the wall. Now Maggies already have more of that putting you into the performance feel, but in this case pulling the voices out into the room made it much easier to understand dialog on movies (and I have volume matched my speakers through my pre-processor's EQ system).

 

So, in addition to trying what you have already done, if you can, play around a bit with the timing of the center channel vs the sides (in distance measurements, I'm talking about a few inches forward or backward). Enjoy!

[Paul R]

What's the advantage of two speakers? Do they just play louder because the resistance is halved, or is it doing something else?

 

Hi Bill -

They are mono, so angling them in at 30-40 degrees tends to make one speaker louder than the other depending on the axis you are sitting on. The result is a pretty stable center image, and as others mentioned, it seems to be well out into the room. Dialog is very much better, especially on British shows. Without the angle, that off axis behavior is vastly reduced and so, I expect, would be improvement.

 

Yeah, there is not count that Netflix, Amazon, Acorn, PBS, and others are doing something audio-wise that doesn't happen with DVDs or Bluray disks. The very loud music tracks and overemphasized bass track, combined with not too bad dynamic range is making them an ever greater challenge, at least to me.

 

Question is, how did you wire them?.....in series?.....or parallel?

 

Hi Mayhem - They are wired in series. It's a mono signal so... I do not think that is a problem.

 

Hopefully those are 8 ohms speakers so you are not feeding your amp 2 ohms loads. I think the center channel speak does most of the work for TV and movies and you really need a good center channel speaker.

 

Hi Lee -

They are being driven by their very own amp, and it can easily handle low ohms and lots of current flow. The Imagine B's are nominal 8ohm, low of 4ohm, and average around 6.5ohms. Not terribly easy to drive, but they voice very very similar to the Synch 1Bs I use as mains. I let the processor feed anything below 60hz to the Sync B1s though.

 

The big issue with pairs of center channel speakers is that their inevitable separation results in a "Venetian blind" irregular radiation in the plane of the separation. Thus, speakers on each side of the display would have irregular radiation, due to alternate beams of reinforcement and cancellation in the horizontal plane. It would be less significant in the vertical plane. A well-designed single speaker would be superior.

 

Hi Kal -

Duhhh..... I am going to have to study that idea to understand it. It may be we have the speakers close enough together to minimize this effect, but I am not sure. We have tried single center channel speakers and found that all the ones we have listened to tend to beam the HF sound in a manner we find unpleasant - though admittedly, some have sounded very good indeed. That seems true of even the more expensive models we have tried. That would be up to the PSB Synchrony 1C at about $2100, and includes Maggies, Martin Logan (the new Motion 30), a Focal Chorus CC700, and several downlevel from that. Many sounded very good, but - for lack of a better description - the "beaming thing" was just not getting there. I do not detect that beaming issue with this, but perhaps I am not listening for the right thing. (Or am just being ear blind. )

 

Paul: As the first Magnepan tri-center customer, I am admittedly a strong fan of that approach.

 

A man after my own heart!! I tried a CCR but thought the dual center was also superior. My better half has this thing about Maggies in the living room though...

 

I have not seen any scientific or hearing-oriented work that proves or disproves the effect, but I do know that Magnepan regularly gets listeners to prefer the tri-center in A/B blind testing. For me, the biggest difference was a sense that the dialog was suddenly "in the room" rather than coming from the wall. Now Maggies already have more of that putting you into the performance feel, but in this case pulling the voices out into the room made it much easier to understand dialog on movies (and I have volume matched my speakers through my pre-processor's EQ system).

 

So, in addition to trying what you have already done, if you can, play around a bit with the timing of the center channel vs the sides (in distance measurements, I'm talking about a few inches forward or backward). Enjoy!

 

I am working on trying to dial them in by position first, though I have ensured they are exactly volume matched. I will be needing to buy a new PrePro or AVR soon, and finger the new software may be vastly superior.

 

Thank for all the neat ideas guys! You have left me with lots of interesting research to explore, and at least I know I am not totally nuts to try this. It sires seems to be a vast improvement.

[mayhem13]

Ok, so series is ok presenting an 8ohm minima to your amp given the specs of your PSBs. Nominally around 12 ohms average so an easy load to drive.......but not nearly efficient. Had they been wired parallel, your impedance minima would have been 2ohms..........not good for all but the most robust amplifiers. Certainly louder....but not for long! Lol

 

Now....a mono signal.....well yes.....but it's important to remember that some if not most of the center channel info is also part of the the LR signal through the mix process AND two drivers playing the same content ( your two PSBs) will present some significant comb filtering dependant on distance and frequency.

 

Now none of this in necessarily a 'bad' thing........just far from multichannel surround specs. But it works for you and there are others who have reported similiar findings. Truthfully, there's all sorts of combing and phase cancellations going on in your situation that would be nearly impossible to predict due to the variables. Again, none of that matters as you and your wife enjoy the sound. I did something similiar in the early days of multichannel HT and really enjoyed it too. We had a 60" DLP and a single center channel above the TV just plain sucked and rewiring the Tvs internal bottom speakers from stereo to mono center was better......but too low to the ground. So two old Bose 901s went on top tilted down ( massive overkill I know !) but sounded INCREDIBLE with extreme dynamic range and imaging. After a while of getting used to it, a distracting quality became apparent in where althought the TV was 12 ft away, dialogue was floating right in front of me instead of from the screen. I applied the artifact part of a highly directive application with the two speakers rearward and fwd radiation creating some odd ball cancellations. It was kinda like watching TV with headphones.

 

......but enjoy what you have going on. It maybe a compromise to the specs, but IMO for multichannel HT....whatever works! I would a only add that my current setup of a 110" acoustically transparent screen with 3 matching front speakers for the L,R and C content is by far the best performance I've experienced to date.

[Paul R]

Ok, so series is ok presenting an 8ohm minima to your amp given the specs of your PSBs. Nominally around 12 ohms average so an easy load to drive.......but not nearly efficient. Had they been wired parallel, your impedance minima would have been 2ohms..........not good for all but the most robust amplifiers. Certainly louder....but not for long! Lol

 

Oh, I expect that the amp here has plenty of go juice even driving a two ohm load. Might try hooking them up in parallel for the heck of it, though I was thinking if it works out, I'll just buy another amp and drive each speaker separately.

 

 

Now....a mono signal.....well yes.....but it's important to remember that some if not most of the center channel info is also part of the the LR signal through the mix process AND two drivers playing the same content ( your two PSBs) will present some significant comb filtering dependant on distance and frequency.[/Quote]

 

This is an interesting point to explore for me. The kind of interference you are talking about usually sounds like a "beat" to me, and I suspect given the distances and such, it would center somewhere around 1800 to 2100 hz. Very audible.

 

So the two Imagine B speakers are about 1.6m apart center to center, so very roughly, that would mean comb filter effects can happen with any wavelength more than 1.6m, and that's about 220hz or thereabouts. But I am not hearing that at all - at least - not yet. That could just as easily be phrased as I am not recognizing that sound - yet. Or it could mean that particular effect isn't audible, at least in this room. I am absolutely not sure what the right answer to that is.

 

Now none of this in necessarily a 'bad' thing........just far from multichannel surround specs. But it works for you and there are others who have reported similiar findings. Truthfully, there's all sorts of combing and phase cancellations going on in your situation that would be nearly impossible to predict due to the variables. Again, none of that matters as you and your wife enjoy the sound. I did something similiar in the early days of multichannel HT and really enjoyed it too. We had a 60" DLP and a single center channel above the TV just plain sucked and rewiring the Tvs internal bottom speakers from stereo to mono center was better......but too low to the ground. So two old Bose 901s went on top tilted down ( massive overkill I know !) but sounded INCREDIBLE with extreme dynamic range and imaging. After a while of getting used to it, a distracting quality became apparent in where althought the TV was 12 ft away, dialogue was floating right in front of me instead of from the screen. I applied the artifact part of a highly directive application with the two speakers rearward and fwd radiation creating some odd ball cancellations. It was kinda like watching TV with headphones.

 

......but enjoy what you have going on. It maybe a compromise to the specs, but IMO for multichannel HT....whatever works! I would a only add that my current setup of a 110" acoustically transparent screen with 3 matching front speakers for the L,R and C content is by far the best performance I've experienced to date.[/QUote]

 

I noticed the floating effect immediately, but our system is quite forward in any case - the soundstage is upfront in the room with depth not going much past the plane of the speakers. I do dearly love that effect. And it was easily tamed with moving the center Imagine Bs around a bit.

 

The two Imagine Bs bring the dialog up to the same plane as the music, just the same as the phantom center channel effect does with only two. I may have to resort to using the AVR to adjust speaker distance a bit, but I am rather hoping not. The back reflection from the Bs is also damped quite a bit with rugs, and that probably helps a wee bit. (It works, my beautiful wife loves the look, and what the heck? )

 

More importantly though, can you drop me a reference to these multi-channel specs you are talking about? I have never heard ay spec that defined the center channel configuration, other than it being mono. I need to study some more.

 

-Paul

[sdolezalek]

A man after my own heart!! I tried a CCR but thought the dual center was also superior. My better half has this thing about Maggies in the living room though...

 

Paul: I totally get where your better half was coming from -- I had to design the Living Room around my Maggies and it still wasn't easy. But I think the end result came out pretty well:

 

 

After a while of getting used to it, a distracting quality became apparent in where although the TV was 12 ft away, dialogue was floating right in front of me instead of from the screen. I applied the artifact part of a highly directive application with the two speakers rearward and fwd radiation creating some odd ball cancellations. It was kinda like watching TV with headphones.

 

Mayhem: As I mentioned in my response to Paul, a key part of making this work right for me was to play around with the delay settings on the pre-processor such that the center voice image was just a few inches in front of the screen but not disembodied in the middle of the room. This takes a fair amount of fine tuning, but also made a huge difference in realism not only for movies but also for 5.1 channel music recordings.

[mayhem13]

Paul: I totally get where your better half was coming from -- I had to design the Living Room around my Maggies and it still wasn't easy. But I think the end result came out pretty well:

 

[ATTACH=CONFIG]11215[/ATTACH] [ATTACH=CONFIG]11216[/ATTACH] [ATTACH=CONFIG]11217[/ATTACH]

 

 

 

Mayhem: As I mentioned in my response to Paul, a key part of making this work right for me was to play around with the delay settings on the pre-processor such that the center voice image was just a few inches in front of the screen but not disembodied in the middle of the room. This takes a fair amount of fine tuning, but also made a huge difference in realism not only for movies but also for 5.1 channel music recordings.

 

Yeah.....in the 'early' days of HT (LoL), there was no on board adjustable DSP in processors or AVRs so no delay adjustments. We lived with the floaters for quite a while anyways! Lol

 

......and again, whatever your fancy is with HT I say go for it! Nothing has to conform to any rules in your own space when 5 or more channels are involved.

[mayhem13]

Paul

 

Truthfully your combing begins 'technically' around 210hz or so, or the first wavelength of the frequency that measures the distance between the center of your PSBs. Generally it intensifies the higher in FR you go........but all bets are off with the series wiring of a speaker system which contains passive filters AND left and right channels adjacent which might contain some out of phase content. As I mentioned earlier......you simply couldn't predict what's gonna happen.

 

As to specs, THX.com is a great place to start.

 

........and a stereo power amp for your center channels wouldn't be a bad idea either!....or add an additional mono block to match the existing......might be cheaper.

[Paul R]

I was just estimating with 220hz, 210hz it is. I am thinking that it would be a wonderfully complex simulation to model just these four speakers just in this room. Perhaps next vacation... :)

 

Yes, it is being driven off a spare mono right now and showing no signs of strain but I think a second mono would be ideal. Always useful to have a spare around!

 

I will go read through the THX setup. I am beginning to wonder what six mini maggies and a couple bass panels might sound like... I could shove the couch up a little closer...

 

 

Paul

 

Paul

 

Truthfully your combing begins 'technically' around 210hz or so, or the first wavelength of the frequency that measures the distance between the center of your PSBs. Generally it intensifies the higher in FR you go........but all bets are off with the series wiring of a speaker system which contains passive filters AND left and right channels adjacent which might contain some out of phase content. As I mentioned earlier......you simply couldn't predict what's gonna happen.

 

As to specs, THX.com is a great place to start.

 

........and a stereo power amp for your center channels wouldn't be a bad idea either!....or add an additional mono block to match the existing......might be cheaper.

[mayhem13]

On an HT bug are we?

 

Gotta say in my dedicated HT room, live concert BDs are simply the only way to fly. It's soooooo much better than 2channel concert stuff.

[Kal Rubinson]

Hi Bill -

Hi Kal -

Duhhh..... I am going to have to study that idea to understand it. It may be we have the speakers close enough together to minimize this effect, but I am not sure. We have tried single center channel speakers and found that all the ones we have listened to tend to beam the HF sound in a manner we find unpleasant - though admittedly, some have sounded very good indeed. That seems true of even the more expensive models we have tried. That would be up to the PSB Synchrony 1C at about $2100, and includes Maggies, Martin Logan (the new Motion 30), a Focal Chorus CC700, and several downlevel from that. Many sounded very good, but - for lack of a better description - the "beaming thing" was just not getting there. I do not detect that beaming issue with this, but perhaps I am not listening for the right thing. (Or am just being ear blind. )

The separation distance for perception of the comb filtering is, generally, greater than 1/2 wavelength of the common frequencies. So, a separation of only 1foot (possible even with two adjacent speakers) will create problems above 500Hz. If you do not notice it or if you have not done the critical comparison, OK. It is a problem for me.

[sdolezalek]

The separation distance for perception of the comb filtering is, generally, greater than 1/2 wavelength of the common frequencies. So, a separation of only 1foot (possible even with two adjacent speakers) will create problems above 500Hz. If you do not notice it or if you have not done the critical comparison, OK. It is a problem for me.

 

The Magnepan discussion groups have a lot of back and forth on this issue (which sounds a lot like the discussions on this site about whether differences between 16/44 and 24/192 are audible). The engineers hold fast to the "comb filtering must produce audible issues" thesis and those who have listened to A/B tests of the tri-center hold fast to the "don't knock it till you've tried it -- it produces highly pleasurable results" thesis.

 

To make matters worse, tri-center involves not just two, but three discrete speakers (two of a different configuration), typically not all in the same sound plane and two of which are side by side and the third is typically above or below. Try to map out the comb filtering function from that. Lastly add that these are all dipole rather than boxed or point source drivers.

[Paul R]

The separation distance for perception of the comb filtering is, generally, greater than 1/2 wavelength of the common frequencies. So, a separation of only 1foot (possible even with two adjacent speakers) will create problems above 500Hz. If you do not notice it or if you have not done the critical comparison, OK. It is a problem for me.

 

I think it is just more a matter of learning what to listen for. Or listening to it long enough fo me to become accustomed to what it is I am hearing.

 

What I am not really understanding is how it is different from a normal stereo pair, or even a normal stereo pair playing a mono recording?

 

I think that is what is confusing me. Why do the same effects not take place with a multi-driver center channel speaker? It just seems like the same physics would apply.

 

Unless center channel speakers are constructed in some manner to null out the issue?

 

Not arguing, just really curious.

 

Also, I thought the separation distance for comb filtering was a full wavelength, not a half. I should hqve looked that up rather than relying on unreliable memory. !

[Paul R]

On an HT bug are we?

 

Gotta say in my dedicated HT room, live concert BDs are simply the only way to fly. It's soooooo much better than 2channel concert stuff.

 

(Grin)

 

It is difficult to do HT right without turning a pleasant living space into a jungle of deadly cables waiting to snap at me or be eaten by cats.

 

At least, it is for me!

 

I tried about three years ago, and was so disgusted with the results I achieved, I just went back to a two channel system, which was very very good indeed. It's only recently that the audio has become problematic with the two channel system.

 

Thus, it is only recently that I once again venture into a multi channel system. It is still difficult.

[Kal Rubinson]

What I am not really understanding is how it is different from a normal stereo pair, or even a normal stereo pair playing a mono recording?

A stereo pair is not getting identical signals. Even when the same single instrument is being reproduced, the two mic pickups from that source will differ.

 

Why do the same effects not take place with a multi-driver center channel speaker? It just seems like the same physics would apply.

They do. Notice that almost every modern speaker has the drivers arrayed vertically. This results in the same comb-filtering but it is now restricted to the vertical plane and all our ears are in roughly a fixed height even when we move around. Note, though, the change you hear as you stand up or lie on the floor.

 

Unless center channel speakers are constructed in some manner to null out the issue?

It really depends on how they are designed but most of the typical inexpensive MTMs suck in this regard since the small mid-woofers reproduce too high into the midrange for the distance which separates them. WMTW designs with the tweeter and midranges stacked vertically can easily escape these problems.

 

Also, I thought the separation distance for comb filtering was a full wavelength, not a half. I should hqve looked that up rather than relying on unreliable memory. !

Well, on the perception level, this is a debatable point since it depends on one's sensitivity to the phenomenon. That there is measureable beaming is not.

[mayhem13]

The Magnepan discussion groups have a lot of back and forth on this issue (which sounds a lot like the discussions on this site about whether differences between 16/44 and 24/192 are audible). The engineers hold fast to the "comb filtering must produce audible issues" thesis and those who have listened to A/B tests of the tri-center hold fast to the "don't knock it till you've tried it -- it produces highly pleasurable results" thesis.

 

To make matters worse, tri-center involves not just two, but three discrete speakers (two of a different configuration), typically not all in the same sound plane and two of which are side by side and the third is typically above or below. Try to map out the comb filtering function from that. Lastly add that these are all dipole rather than boxed or point source drivers.

 

Combing is certainly real and very audible. In your system as shown, you're simply overcoming the pitfalls with sheer radiating surface area. Your arrangement is certainly not Typical or easy to implement. But as I mentioned to Paul, if it works in your environment when HT is concerned, go for it!

[Paul R]

Combing is certainly real and very audible. In your system as shown, you're simply overcoming the pitfalls with sheer radiating surface area. Your arrangement is certainly not Typical or easy to implement. But as I mentioned to Paul, if it works in your environment when HT is concerned, go for it!

 

Okay- but as far as I can tell- comb filtering is *always* an issue in every room. I think I see why the issue raises hackles here, but comb filtering to me has always sounded - metallic and unpleasant. I am not getting any of that with this, possibly because so much of the material is fed through the center channel. No listener fatigue either, which is what I would expect..

 

Reducing to a single center channel speaker, arrayed vertically does not seem to make any change in the quality, but it sure changes the prime listening area to a very small restricted area, and that nuisance beaming issue makes itself evident. Perhaps any issues present from dual speakers for a center channel array are overridden by the nasty beaming behavior, at least for me..

 

Dual speakers eliminate that issue for certain!

 

Now, as far as I can tell, most of the center channel speakers out there tend to have this same problem as well, if for no other reason than they have two or more speakers separated by only a foot or so, and are also arrayed horizontally, which if I am beginning to understand correctly, just adds to the problem, at least for those who can hear this problem.

 

I played with delay on those speakers today, a well as with positioning, and there was a point where everything snapped into focus very exactly. Nice.

 

In my particular case, the two sets of speakers are close to each other, and have a distinct configuration that may be helping to avoid this issue. That would be at the Synch 1Bs have the woofer on top, while the Imagine B's have the tweeter on top. Playing with the physical height of the Imagine B's made a considerable difference in the sound. I think some of the issues you predict are eliminated by the horizontal sources being coordinated this way. Could be a crazy idea, but hey- just playing here.

 

Also, the material playing from the fronts is - apparently - quite different than what is coming through the center. And for 2ch music, like a ballet, the fronts take on almost all the work, while the center channels seem given over to producing great gobs of silence. Wonderful.

 

Obviously, this could turn out to be quite wrong, but it is a fun experiment, and sounds better than any single speaker center channel I have ever tried. Blends absolutely seamlessly to us. And two channel playback is unaffected by any of this. I have a set of NHT SuperZero 2.1s here I may try out on a second system to see how that plays out. They are inexpensive enough I can order two or three extras - and if it doesn't work out, I got Christmas and Birthday presents for some people.

 

Paul

[mayhem13]

Comb filtering as we're discussing it results in cancellations, the more intense the effect the more a perceived loss of high frequency content. It can exist in both the horizontal and the vertical so adjusting speaker positions in both planes can certainly help as you've experienced. Typical horizontally aligned center channels as Kal mentioned do seem to 'beam' high frequencies, but that's not what is really happening here. This may help....

 

Directivity......for a particular driver's diameter, the driver will direct its energy in a narrow, direct pattern. At this point, it begins to 'beam' as we call it. There's small variances as to exactly when this happens such as the driver's profile, phase plugs or dust cap size,etc but pretty much 1/4 wavelength of the frequency at the nominal diameter. So a typical 1" dome begins beaming up around 3.5khz or so. Move off axis, and the effect is audible the farther you go. For audiophiles for many years, the intersecting point of the radiated energy from the tweeters determined the 'sweet spot'. The smaller the spot, the more limiting of course. Horns and waveguides certainly help and for large spaces and concert, line array technology is employed to 'direct' energy evenly over a given area...........

 

.......back to what we were talking about and perceived 'beaming'. Normally the radiated energy from the midwoofer would share that same plane up to its limits above the crossover point giving a nice balanced response. But when we consider 'two' midwoofers on either side of a tweeter is where destructive comb filtering begins. The drivers radiating energy at and above the frequency of the wavelength of the distance seperating them from center to center begin to cancel. The higher in frequency, the worse the cancellations leaving the highly directive, beaming radiation of the tweeter. Move off axis in these cases, and vocal intelligibility is completely lost. Kal mentions above with the typical horizontal MTM center channels.....the worst compromise to allow for a convenient center channel mounting.

 

So what you and others have discovered is if you use multiple speakers for center, experiment with distance horizontally and vertically and apply delay accordingly you can eventually find a nice center channel field of operation. Now it's important to consider what you've gone through to accomplish this. It takes some work, some additional equipment and time as well a processing. For me and you and other audiophiles, tweeters, enthusiasts.....whatever.......we don't mind the work or effort. But the real kick is that there's a much simpler, predictable and better performing solution with a simple vertically aligned point source properly placed. Proper 'placement' is right in front of the display! Lol.....but seriously......the simple compromise is below or above the screen angled at the listeners. If the system has good off axis response, at a typical listening distance center channel info should cover the seated area better than other options as phantom centers and the things you and others have been experimenting with. Those 'simple' above and below compromises often aren't very simple a many displays are low to begin with, so placing the speaker below often interferes with the typical occasional tables in front of living space seating and such. Above, limitations become shelves or a basic aesthetic avoidance to place a single vertical speaker above the display.....it just 'looks' odd to us so we avoid it. Slim it down and stretch it linearly to match the display though....and it looks 'better' to us and seems to be a good fit.......but from a performance standpoint it's anything but a good fit.

 

So hope this helps.

[sdolezalek]

I played with delay on those speakers today, a well as with positioning, and there was a point where everything snapped into focus very exactly. Nice.

 

Glad that worked well, I found the same thing in doing trial and error on both positioning and delay. Still wish I better understood what the psycho-acoustic phenomenon was that makes this sound so much better than a single center channel. So far, I have heard reasons why it should sound worse (comb effects), but none to explain why the opposite could be true.

[Paul R]

Comb filtering as we're discussing it results in cancellations, the more intense the effect the more a perceived loss of high frequency content. It can exist in both the horizontal and the vertical so adjusting speaker positions in both planes can certainly help as you've experienced. Typical horizontally aligned center channels as Kal mentioned do seem to 'beam' high frequencies, but that's not what is really happening here. This may help....

 

That was very helpful, thank you! The only thing that I wish to bring up with this is that comb filtering, at least so far as I am aware, can reinforce a set of frequencies as easily as cancel it out. Unless, as there very likely may be, there is some operator that prevents that.

 

I am beginning to doubt that any Center Chanel speaker in our space can do as well as a dual speaker setup, but I have not totally worked out why. In fact, I have barely started. And it may, in the end, prove to be false and we wind up with a single CC.

 

Found a few other datums that do not exactly fit into my limited understanding yet... Using a different brand of speaker can prove very undesirable results. I put a set of NYT Superzero 2.1s in place and immediately heard exactly what you guys are talking about. Conversely, a set of Maggie MMGs, when used sounded much much better- perhaps because of the greater radiative area that you or Kal mentioned. Yi yo I!

 

Confusing, and difficult! Impossible perhaps, without digital room correction..

 

Paul

[Paul R]

Glad that worked well, I found the same thing in doing trial and error on both positioning and delay. Still wish I better understood what the psycho-acoustic phenomenon was that makes this sound so much better than a single center channel. So far, I have heard reasons why it should sound worse (comb effects), but none to explain why the opposite could be true.

 

Yes, absolutely. And another thing that bit me was the types of signals being decoded. DTS vs Dolby vs something else, yeep! They all have slightly different settings too- including dynamic range adjustments that that make things terribly confusing..