Axiom Home Page Forums General Discussion Home Theater 2 center channels in parallel?

Has anyone experimented with placing 2 center channels in parallel, 1 above and 1 below the TV screen? This would seem like a way to stop localisation of the center. I find this particularly annoying for multi channel music where my front soundstage is pulled down by my VP150 which is below my TV on a shelf.
A friend of mine has an acoustically opaque screen in his projector theater which allows him to play his center channel through the screen. We were brainstorming ways of achieving the same effect with a RPTV system today and this seems like a possibility. Of course it would end up as a 4 Ohm load, but this shouldn't cause any problems with my Denon reciever.
Anyone tried this?

Stuart

Yes, Stuart, that would work well. If you've looked at the pictures of Ian's setup, you'll notice that he has VP150s above and below his screen. Before you consider that, however, have you tried tilting your VP150 slightly upward, possibly by flipping it over onto the slanted side?

Hi Stuart,

A gracious (former?) board regular initiated a couple of lively discussions on this topic, focusing primarily on the use of two M2ti's, but the concepts may be applicable to your question also.

See this one and this one

Hope this helps.

- Tom

Thanks JohnK, where can I find the pictures?

I've never been totally happy with any center channel speaker that I've used because of that nasty localization effect you mentioned. I always thought that it (center channel) was a necessary evil so I never tried the phantom center until a few days ago.

I found that I like it much better. Very seamless pans across the front and no center speaker localization and always true to scale across the front soundstage as long as you are in the sweet spot. Even sitting slightly off center, it doesn't sound bad.

I've always had to place my center speaker just below the TV and although it was almost at ear level it still brought the center image down in scale as though the center material was only as tall as the center speaker.

I've never tried two center channel speakers but on the surface it seems to make sense. I would think that you would get better soundstage scale with two as long as they were positioned properly.

Aside from off axis seating positions, can anyone tell me the draw backs of the phantom center?

I tried a number of configurations using 2 M2i's as a center channel. I don't remember the details but fortunately I posted a long babbling thread about it.

http://www.axiomaudio.com/boards/showflat.php?Cat=&Board=HT&Number=63733&page=&view=&sb=&o=&fpart=2&vc=1

I ended up with a single VP100 on top of the TV but I think the main reason was magnetic interference when I put the M2s too close to the TV, particularly on top/bottom.

Once I got the VP100 I was happy with center performance and never tried running 2 shielded centers, but I think it should work OK.

The other trick is to just play with the height of your mains a bit so that the mains are a bit below center of the screen which helps balance out having the center above the screen. If the center is below the screen lift the mains up a bit etc... (I mean move vertically, not tilt).

Link to thread.

bigjohn

Well, I finally borrowed a VP100 (oh, you want it back, Peter?) and hooked it up last night (had it for a week, just hooked it up, what the hell is wrong with me?). I had it sitting vertically next to the TV. I was appalled by the localization! Why look, there's all the sound, just to the left of the TV... I moved it to the top of the TV, and then all the sound was on top of the TV! I finally stuck some coasters under the back, and tilted it down towards the listening position, and that seemed to work better. It's definitely different (dare I say it, a tad bright with TV watching...), but I need to find out what my wife thinks. I know that she wants it slightly behind and a wee bit lower than the top of the TV, but I don't have the bits and pieces in place to try that.

Whoops, didn't mean to side track... I've heard some very good things about putting centers below and above the screen. Judging by what Bridgeman said, it would probably work better than 2 centers on the sides of the TV.

I have a Yamaha NS series center speaker in my living room set up. Sometime this week I will poach it for a few hours to check out the effect. I am assuming that I can simply daisy chain the 2 speakers together.
Voicing etc. will be all wrong, but I should get a general idea about whether it is worth investing in another VP150.

My VP150 can be very easy to localize. I just asked a question in another thread about this. Proper calibration always ends up with the correct VP150 setting somewhere between -3 and -4dB below the front channels. My AVR only has 1dB steps, so I always went with -3. For some reason or another I always bumped it up that 1dB because -4 just bothered me. I ended up setting it back to -4 because it was drawing attention to itself during loud scenes. Now, the soundstage is perfect.

That extra 2dB sensitivity rating, and the 2 ohm difference in impedance combine to make a huge difference. When very loud scenes happen, the more efficient VP150 makes better use of the additional power, and it outputs more raw sound energy than the front speakers do. Try an experiment. Lower the VP150 a dB or 2, and see if that helps.

As far as angling it goes, I like the way mine fills out the soundstage better when the front of the drivers are vertical. I have an 8' ceiling, and the TV that the VP150 sits on is just under 6' tall so there is a reflecting surface just 2 feet above it. When I angle it down so that it points directly at the listening position, the soundtage seems to have a hole in it above the TV that is noticable during spaceship & airplane flyovers.

Just realised the VP150 is only 6 Ohm load, could be 2 of them at 3 Ohms will be too much. Anyone know how the VP150 actually measures in real use conditions?

Stuart, scroll down to 6/27/03 in this thread for one.

Mike, as you may recall I've suggested use of the phantom center several times here and use it myself in appropriate situations. As far as I'm concerned there is no disadvantage other than the shift of the centered image when the listener moves left or right. The fear of additional "comb filtering" when the same sound is reproduced from two speakers and the listener isn't centered isn't justified in my experience. Comb filtering goes on all over the place in any live listening room.

John, I do recall you suggesting the phantom center but I just thought you were full of hooey.

Seriously though, I've been using phantom for several days now and I'm just delighted. I see no disadvantage either. As far as "off center seating" goes, it (dedicated center speaker) may serve to anchor the dialog to the TV a little better for the off center listener but lets face it - off center is off center and the listener is going to suffer soundstage collapse anyway.

And since no one at my house really gives a $hit about imaging and soundstage and such, and since my Lazy-Boy is in the sweet spot, I think I'll just leave it in the phantom mode indefinitely and see if anyone notices.

If I get the lazy boy again when I come over again, you'll hear no complaints from me.

You are welcome to come back anytime and take the Lazy-Boy. I've made a few changes since you were last there. So, whenever you feel froggy, just hop on over.

if u don't want sound localized, how about a qs8 as center?

Type_E,

It would be interesting to hear what that would sound like but would be an unnecessary expense IMO. I'm now a firm believer that the best center is no center unless all front speakers are identical (although very impractical).

With phantom center (at least for the person[s] sitting in the sweet spot) the front sound stage is absolutely seamless in scale and there is no worry about timbre match.

In my experience, dedicated center speakers, even the ones with the same driver[s] as the mains, don't sound the same as the mains in timbre nor scale. This is easy to demonstrate simply by playing some pink noise in sequence from L-C-R. An A-B test between center and phantom will reveal differences in timbre and should be easy to distinguish.

P.S: To JohnK - thanks for putting that phantom bug in my ear.

P.S.S: Dammit JohnK, now I'm thinking about selling my center speaker.
But wait, maybe if I sell it I can get a HD PVR for my dish.

Nice to hear that, I currently have a 2.1 setup waiting for my year end bonus for qs8. If phantom center is a solution, then my system will be completed very soon.

Ken just returned my VP100 after borrowing it for a week. While it was out, I tried the phantom thing and I was very surprised with it. I watched Master and Commander and the dialog was well centered, but only sitting right in the middle. Sounds great!

I just did a bit of testing to see if the same idea could be used for a "phantom sub". Worked real good except the bass sucked

Funniest thing I've read tonight...