Center Channels a Gimic? (1 Viewer)

[Mark Seaton]

If adding a center channel doesn't improve the sound, the system probably isn't set up right, acoustics and nearby objects are killing the performance, or your center channel sucks. Many center channels are pretty disappointing, but there are certainly some very good ones.

I havent' seen anyone even mention the problem of comb-filtering from a stereo-produced center image. A good center channel or identical speaker in the center will sound much clearer than a pair producing an image. No magic, simple fact.

 

[Evan M.]

Where did someone say this Lance? Let me know and I'll jump ugly on them because I LOVE my Boston VR3's !!!!!!

 

[Kevin C Brown]

Ahhh, but because the stereo pair of speakers would be a lot further away from each other than mids contained in a single center speaker, isn't that effect negligable? Wavelength distances an' all. Well, I guess depending on how far the stereo speakers are apart.

 

[John Garcia]

With a good recording, combing between the left and the right shouldn't be an issue anyway, as they aren't playing exactly the same thing. Each playing something slightly different from the other is what gives you the imaging.

 

[Mark Seaton]

I believe you are thinking of comb-filtering in the context of adjacent drivers through the crossover range of a loudspeaker. While not un-related, this is a different situation.

Consider that if you want a true center image you will send a mono, or identical signal to L & R speakers. With two speakers playing the exact same signal, there will only be one equidistant location where comb-filtering will be zero or at a minimum. We have two ears, separated by the width of our head (duh). There is no way you can have both ears in this "ideal" location. Measurement at each ear location will quickly show comb filtering at one or both ear locations.

A capable center channel should easily provide consistent response across the width of a seat, and certainly the width of our head. The difference is quite noticable with dialog or a solo singer.

 

[LanceJ]

I totally believe what you're saying, but for most people, I think reality rears its ugly head & can screw things up:

* Center channels can get placed in some really bad locations because of practical concerns i.e. 2 feet above the monitor in the "slot" the builder of the entertaiment unit thought would be a good place; on the bottom shelf a few inches from the floor because their LCD RPTV only has a narrow strip of cabinetry on top & won't allow any speaker to be placed there, etc.

* I almost never see centers horizontally-even with the left/right mains. For example as a car travels across the screen it exhibits sort of a rollercoaster effect, which is obviously not very realistic.

* Most peoples' living rooms are acoustically "messy" - maybe if they had a dedicated theater room that wouldn't be a problem but AFAIK this still requires some quite expensive room treatments and possibly professional advice to attain the proper acoustics.

* Really good center channels are expensive & they also are usually quite large. The $$$ issue is not a big deal for many people but to others having a huge 40lb box sitting next to their beautiful HDTV just won't cut it. I'm using a pretty chunky Infinity bookshelf speaker as my center (@16Hx10Wx8D), sitting on a short stand in front of the 27" TV - this doesn't bother *me* but my female friends make ugly comments about it every time they see it (my response to them: :p) ). So I'm not surprised it seems like 95% of all centers are of the dual 5" woofer/single tweeter type.

 

[Kevin C Brown]

Mark- It might be because room reflections overwhelm the version of comb filtering that you're talking about. However, it is said that with speakers capable of very pinpoint imaging, that there is a very small window of that pinpoint imaging. (I'm thinking of time coherent, phase aligned driver designs like Vandersteen, Dunlavy, Thiel, among a very few others). I had a pair of Vandersteens that were like this. The sweet spot was oh so sublime, but oh so small.

 

[Leo Kerr]

In my own experience, I find that "properly calibrated" the center channel is usually a tad on the hot side. In generally, I'll calibrate, and then back the center off by 1dB or so; it helps the center to "disappear" in the image.

Leo

 

[Mark Seaton]

Leo, Sometimes another effective method is to decrease the distance set for the center channel in your pre-pro. This works best if the distance increments are less than 1'. Localization is dominated strongly by first sound arrival; even more so than level. This way you can keep the dialog clear while helping to make sure sounds present in the left and right are as expansive as possible.

The fact of comb filtering from a stereo pair and the improved clarity of a center channel is not a new one. I would have to do some searching, but there have been very conclusive studies, and anyone with 3 of the same speaker can experiment at home.

Acoustic and placement issues with a center channel are important, although I would say given more credit than they should in the above arguments. While there are certainly exceptions, a large majority of the better center channels are 3 way designs with a vertically oriented tweeter and woofer. Not all of these are great, but they are often harder to screw up. :rolleyes

 

[Alan Wise]

My system consists of six identical monitors, a center and a sub. The placement of my center was a concern because of the narrow strip and steep angled drop off on the top of my 60" Hitachi LCD RPTV. I still wanted the speaker on top of the TV so I took two pieces of styrafoam (speaker packaging material)and cut them into wedges. These wedges allowed me to adjust a very slight downward angle of my Boston VRC center (yes Lance I too am a Boston fan)to point it towards the main seating position. I then placed my left and right main speakers (yes, more Bostons)with their tweeters set at the same height as that of the center channel. I am very satisfied with the imaging that I have achieved, and can not not find any off center listening area differences, even with two recliners out at the flanks. I do like the effect that the center channel provides especially where dialogue and background noise occur at the same time. It feels like someone is talking directly to you from the TV screen while a car can start up and drive away, panning from the left or right mains to the side, then back surrounds. I guess I am a surround sound fan indeed. I am 80/20 Movies/Music though, and I might feel different if I was more into music listening. But, then again this is a "Home Theater Forum" is it not?

Regards, Al Wise

 

[AlanZ]

Al: Not only do you have a good name, you pretty much hit my exact reasoning for going w/out a center. Though I am also an 80/20 movies to music person, the quality of my 2-channel reproduction is MUCH more important to me than the quality of my movie sound. I think most people would agree that it's much easier to get good sound for HT than it is for music. The money that I COULD put into a center channel is much more valuable to me when I apply it toward better mains. Better mains makes more of a difference with music than a center channel does with HT. People can throw out all the technical points they want to, the ultimate judge is my own hearing. But anyway, my main point is that to me it's not so much which of the two applications you spend more time with, it's which one of them is more important to you in terms of the best sound you can afford. For me, it's music.

Okay, I'm off to watch a movie now....

 

[drobbins]

Heck, I use two centers!!
I have JBL E30s for R & L and a JBL EC35 for a center. With a 105" screen, it is impossible for me to put the center aligned with the R & L. I found myself looking at the bottom of the screen during dialog and moving objects like cars did the roller coaster thing as they went across the screen. So I added a second small center above the screen wired in parallel. This also helped deliver the center sound to the second row of seating. If there is any combing going on, I can not tell. As stated before, If you are happy with the sound, that is what matters.

 

[Bo-Cephus]

New to this forum, but from what I've heard it's generally optimal to from "true" reproduction to start with the intent of the authors, including how it was mixed and processed, stereo, multichannel, etc.). I'm sure room size and acoustics would impact type and placement of the speakers, but it seems that using a setup different than the intended compels trying to "fool" the listener to recreate the original concept (believe me I know - I'm switching from Bose, whose made a living on trying to fool the listener). But of course, listening is individual, and if you're more comfortable without a center and you have the speakers to handle it that's great. Personally I'm using a center since most of what I listen to is produced for that format. Obviously good to great fronts are intended to recreate the soundstage, but if 3/multi channel audio is run through 2 channels it seems there would be more involved to recreate the intent, especially movies.

Also, if this logic is taken to the extreme, then wouldn't it make sense that rear speakers could also be unnecessary if the fronts are good enough at projecting the rear-channel audio? I know it's a little different, but again, the intent of an HT system is to more accurately reflect the author's intent, which for me means using the same number of speakers as was used creating the audio. Since I'm new to this and here to learn, though, please respond and/or correct anything I'm assuming. I welcome and am grateful for your comments and feedback. Thanks.

 

[Charles-T]

This is some of the craziest rubbish I have read in a while.

I'm sorry, but you DO NOT have to have a center channel to have "true surround sound". Apparently, you don't understand the recornding process either, considering there's no such this as "true surround sound" to begin with, unless you just go walking around outside in with your own two ears.

Surround sound is made by a bunch of guys in a recording booth shoving sliders back and forth, to and fro, directing certain tracks to certain channels to simulate your "true surround sound".

If you have good quality main channel loudspeakers, then NO, you do NOT need a center channel. My Klipsch Cornwalls do a better job of keeping movie dialog front and center than any dedicated center channel speaker ever has in my system. In fact, the Cornwalls put the dialog right in the middle of the screen. I don't mean just left and right either, but half-way up the wall where I have the screen mounted.

And as for SACD and DVD-A, I certainly wouldn't build my system up for those formats, especially when it looks like both of them won't last much longer anyway. I probably have about a dozen SACD amd DVD-A discs and prefer the 2-channel layers (mixes) better.

If you have your loudspeakers set up properly, then you don't even need rear surround speakers for music. Again, with my Cornwalls, I can pop in a regular (good quality recorded) audio CD, close my eyes and hear the music all around me. This is what's known as imaging and soundstaging, and it's much more real and convincing sounding than those silly 5.1 audio mixes.

I was actually considering building a matching dedicated horizontal Cornwall center channel with the same exact drivers, horns, crossover networks, enclosure size and tune. But the more I watch movies with just the front two channels, the more I like the idea of saving my money and not going with a center channel. I can take that money saved and put it towards upgraded crossover networks or something.

Anyway, I didn't mean to get on a rant here. Sorry...

 

[AlanZ]

Good post, Charles....I couldn't agree with you more. People want to make all these technical arguments for a center speaker, but when it comes down to the ACTUAL differences in presentation, the arguments are basically meaningless in my opinion. But again, I'm not disparaging ANYONE from having a center speaker if that's what they prefer. I just like to let people - particularly newbies to the hobby - that you don't HAVE to have one, and in fact many of us PREFER to go without.

 

[Leo Kerr]

It also goes to suggest that it's not just the playback setting that makes a difference, but the recording as well.

I've heard some truely excellent stereo mixes that were just as surround-compelling as some of the most subtle DTS mixes (not to get into a format-war, but I've only heard CASPER in DTS, and it has one of the best atmosphere/environment tracks I've heard.)


But there are also some real klunkers of sound-recordings; mono, stereo, or 7.1.

Leo Kerr

 

[Jack Gilvey]

The primary purpose of a center channel is to anchor dialogue to the screen for off-center viewers, not to enhance sweet-spot imaging. If I only watched/listened alone from the middle of my couch, I probably wouldn't bother with one either.
The ability of stereo speakers to throw a convincing center or "surround" image is compromised outside of a rather limited listening window, although such can be quite engaging in the right spot.

 

[Bo-Cephus]

Hope at least my comments weren't considered a value judgment, just my take on things. Obviously if a setup realistically "puts you there", goal achieved. Big differences between opinion, technical expertise (of which I have none), and preferences. OK as long as they are kept in the proper categories.

I'm still on the relative low end in terms of money invested in HT speakers (B&W 600 series). But even at this lower price point, I was amazed when I asked the sales associate to turn off the center channel to hear just the 2 fronts, and he told me it was already off.

I also understand Charles's point re: location of voice in center channel between above or below the screen, vs. in the center of the screen. For those of you w/centers, is there anything that can be done to deal with this, besides putting the speaker behind a projector screen? Thanks.

 

[AlanZ]

Jack: Good point....and that's probably the only reason why I'd ever get a center speaker. I'm the kind of person that if I have someone over who I really want to benefit from the best audio experience, I give them the 'good seat', lol. Otherwise, if they don't really care, then I relegate them to one of the side seats

 

[Jack Gilvey]

F*ck 'em, right? I usually take the loveseat off to the side myself, and let guests have the couch which spans the width of the screen. Even when it's just the two of us, I tend to sit on either end, which puts me appreciably off-center.