Call me crazy but I have lots of experience using two speakers for the centre channel and in no case did the sound ever appear to come from two distinct points. In fact it appears to come from a point halfway between the two speakers (ie. centered on the screen.)

In one set-up I had two speakers, one velcroed to each side of an HDTV. The vocals appeared to come from the screen, and not from two different points.

I currently use two 60lb floor standing full range 33" speakers, aligned tweeter to tweeter, suspended above my HDTV, in a custom built frame, achored to the wall and tethered to the ceiling. Vocals appear to come from the centre line of the screen - and not as two point sources.

Take amy two speakers and make an equilateral triangle with them and yourself. Play a mono vocal source. What do you hear? Answer: sound coming from mid-way between the two speakers.

curegeorg: what is your personal experience with using two centre channel speakers?

Jeff Mackwood

like i said, i dont claim or pretend to claim that i have used two speakers as my center channel. it is a bad idea, thus i have not, nor will i ever do it (unless there are 2 outpus for center channel in the future, i.e. stereo center channel). having two speakers play the same signal does not make the sound sound like it is coming from between them, it makes it sound like the same sound is coming from both of them. i have done that, two speakers same sound (mono). voices, dialog, high frequency sounds, etc. all come from the tweeter (take off your grill and feel during a speaking scene of a movie). tweeters are not designed to be in close proximity to one another. as sound radiates out of any speaker it travels via sound waves in a vshaped path, these waves normally have no problem reaching the target without interference. in higher frequency sound especially, their can be interference if a wave of a frequency overlaps another wave of the same frequency. this does not yield 2x as much sound at that point, it changes the sound. who was it that said two particles cant occupy the same space at the same time? newton. the same can be applied to sound, however, the waves can occupy the same space, because they turn into a slightly different wave at that point and further will be distorted. i.e. the sound before the point where they overlap is sound x, the sound after the point of intersection is sound y. the sounds are similar but not the same. MAYBE you can get the sound y to be what you like, but it is not going to be accurate no matter what you do. low frequency sound behaves a little differently because of its longer wave lengths, sometimes these waves lengths can get near parallel to each other and cause a coupled effect. high frequency doesnt do this because the wave lengths are so short, it is nearly impossible to get them to be near parallel...

not to mention that high frequency sound is pretty localized, just as low frequency is not. so to say that two speakers have an effect of sound in the middle is absurd, your mains dont have that effect if you feed them a mono signal. other things have to be done to simulate a center from two mono signals fed to two seperated speakers.

you guys that say, give it a try and see what happens, just dont know. sometimes i dont know, and say give it a try. really the point is moot, because if you want to experiment and waste your time and money, then do it. as long as youre happy, im happy for you. however you will be losing clarity for your center channel, at the sacrifice of more sound. you could GAIN clarity and GAIN more sound by just buying a good quality center channel.

not to mention that center channels have a different axial alignment of speakers than do other speakers, and changing that axis throws of the dynamics of the sound designed for the center channel. i.e. instead of having a horizontal field targeted at (or at least encompassing) your seating position, you would get a vertical field slicing through your seating position.

also sound travels very quickly, but sometimes you can hear a slight delay coming from two seperated speakers playing the same sound (mono). this has to do with more than the sound traveling out from the speaker, but the effect is that the sound arrives at your ear at 2 different times.

there is a lot of things going on with the reproduction of sound... you cant forget that these physical properties exist and influence everything that comes out of your system.

that is ALL i am going to say about how having two center speakers in an ht is a dumb idea. suit yourselves. i prefer my sound as distortion free as possible though.

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This post has been brought to you by curegeorg, thanks for reading.

It is impossible to say if a sub is good or not based off of the right specs without listening to it, but you can sit there and write a thesis on how it is impossible to blend two speakers together without ever trying it.

This is sort of silly now. There are numerous people who actually choose not to have a center channel and instead use their left and right channels and a "phantom" center (I recall azryan speaking at great lengths about the benefits of this arrangement). We also have someone with firsthand experience successfully using this arrangement. From where I'm sitting, you seem to be taking basic principles and twisting them and hammering them into a shape that allows you to make a blanket statement that "two mono center speakers is absurd." (Sort of like the old contractor rule of thumb: "beat to fit, paint to match.") Yes, it is possible to set up two center speakers and have it sound terrible. It is also possible to set them up so that they would work.



Maybe this is true in some cases, but I've heard a mono signal from two speakers that appeared to come from a single point. It can work...

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gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

I hardly think there's one lonely center channel sitting behind the screen at your local megaplex.

Mike

Uhhhhh.....last time I checked, playing the same mono signal through two identical speakers produced a phantom image mid-way between those two speakers. If they do not, the speakers are out of polarity! Just about every stereo recording that contains a vocal has had that vocal reproduced as a phantom image midway between the two speakers. There's a little knob on mixing consoles called a "pan-pot" that allows this technological miracle

[This message has been edited by soundhound (edited June 06, 2004).]

Actually there is just one center speaker in a movie theater. The left and right stage speakers do not routinely reproduce dialog, but rather just sound effects and music. If there is a problem with that speaker not producing enough outut for a particular auditorium, the solution is simply to specifiy a larger speaker rather than using multiple speakers reproducing the same signal.

For the home though, two speakers producing a phantom image is just fine - like I posted above, all stereo (and multi-channel as well) recordings have information panned equally to both speakers and all points in-between. In a home, dialog intelligibility is not nearly as great a problem as in a large movie theater.


[This message has been edited by soundhound (edited June 07, 2004).]

Nice to know I was not imagining it, or worse: pretending that I knew what I was talking about even though I didn't really have a clue. I hate when that happens!

Jeff Mackwood

That vocal mixed in stereo is usually a mono signal. You can simply extract that vocal out by using an old Dolby-Pro Logic processor or anything that can generate center channel and put it with your regular phantom stereo along with slightly gain boost. You could have a very clear center image by using this method. I use three mono center (extracted) plus 4 regular stereo. (unextracted)

[This message has been edited by theendofday (edited June 08, 2004).]

Believe it or not, when using songs that were recorded in stereo for inclusion into a film mix, this is exactly how the engineers extract the lead vocal for mixing it into the center speaker. They use what is called the "Dolby 3" mode which does not attempt to extract surround information - the surrounds are created by delays and reverberation.