Axiom Home Page Forums General Discussion Home Theater Interesting Centre Speaker Discussion

At some point (whenever I upgrade my CRT TV to a wall mounted LCD) I plan on replacing my M80's with W22's. Based on discussions about using matching speakers for LCR, I was thinking about using another pair of W22's as centers, one above and one below. My thought was to have the tweeters on the horizontally mounted centers positioned on the outside. Is this flawed thinking or would that work? (Using a another pair of W22's as centers that is.)

I think I'd use a pair of W100s before using a pair of W22s in a horizontal array.

Joe Vassallo told me a story in July, 2005 about its origins. Apparently Joe was unhappy with the falloff in dispersion at the back of his HT with the the more conventional MTMTM configuration and invited Ian over to listen for himself. They then experimented with the present TMMMT in the vp150 to achieve a better off axis response in Joe's HT.

Thanks, Jakeman, for telling the story of the listening comparisons with Joe and the array of drivers in the center channel speakers.

Your quote below prompted an added thought:

"Hence even with the same drivers as the mains there will be a slight change in tonality and timbre."

What is interesting is that even using identical speakers--not just identical drivers-- for the front left, center, and right channels, if you use pink noise as the test signal, the three identical speakers may have audible differences in tonality and timbre because of interactions with room boundaries and reflections.

These are detectable with pink noise, but once you use vocalists or dialogue as signals, the differences become difficult to detect, unless of course there are gross location differences in the room, e.g. if the left speaker was in or very close to a corner, and the right speaker was not, with the center between them.

You can even experiment with this with left and right mains and pink noise in stereo only. Depending on variables in your room, they may not sound identical using pink noise. It's an illustration of just how influential the room is in affecting the timbral balance of each speaker.

Regards,

Regards,

I thought the idea was to use the same speakers across the front if possible. Or am I missing the point of the discussion ?

I agree. I thought that the same speaker would give the best sound but wasn't practical due to the fact that the speaker would likely be into the monitor. Which led to the discussion of putting either 2 of the same speaker (say M80's) on either side of the monitor, or 2 matching speakers above and below the monitor. I think I am more confused now than I was last night at 2 AM. LOL. I guess I am just a newbie too because I have no idea what pink noise is. Sorry

Pink noise is the test signal receivers send to each channel during the calibration process. It contains an equal level of sound energy across the entire audible sound spectrum. Here's a sample:

http://www.luxevivant.com/samples/DigitalPinkNoiseSample.mp3

Kyle, yes the ideal would be to have a center speaker identical to the mains, if possible. This is possble, for example, when there's enough room beneath a projection screen or a flat panel TV to use even a speaker as large as an M80 there. Where this isn't possible one alternative which in my experience works very well is to use a small vertical speaker(e.g. M2, etc.)which has similar response to the mains above the low bass, and place it immediately above or below the screen. Yet another option is to use dual center speakers either directly at the side of the screen or at the top and bottom edges.

The frequently adopted solution of course is to use an MTM configuration which as was said before was designed by Dr. D'Appolito for vertical use with a narrowed vertical dispersion, and instead for aesthetic reasons place it horizontally, contrary to the intent of the design. While this may be acceptable in general, the tests showing off-axis irregularities illustrate that it's far from optimal.

Other solutions using a horizontal shape include the TMMMT configuration of the VP150, which is said to be better in this respect. The best horizontal center I've heard used a W T/M W configuration which in essense is a small vertical speaker handling the mids and treble flanked by two woofers. At least two members here have centers from manufacturers who use that design. In the past I've wondered how an Axiom center using two of the 6 1/2" drivers flanking the regular tweeter above the 4" mid from the QS4 would do in a roughly 9" x 25" enclosure.