Axiom Home Page Forums General Discussion Home Theater speaker orientation

When placing bookshelf speakers (M22) in a HT setup, are there any problems orientating the main speakers horizontally as opposed to the traditional vertical setup?

Orientation horizontally is OK. I would suggest putting the tweeters to the inside. Due to the angles on the cabinet you will need to support the back of the speaker to have them not face the ceiling.

Ian Colquhoun
President & Chief Engineer

In that case, would the M22 would make a good center channel speaker? How would it compare to the VP100 and VP150 for this purpose?

There are in fact a lot of similarities between the M22, VP100, and VP150. Two M22s for a center channel would be a lot like a VP150. Just one M22 as a center channel would not be as good as using a VP100 because with the single M22 you would have different responses from the left to right.

Ian Colquhoun
President & Chief Engineer

How about if the M22, as a single center channel speaker, was placed on the floor in front of the TV (not obstructing of course) -- how much worse would the M22 be compared to a VP150 on top of the TV? I'm trying to align the heights of the L+C+R tweeters within 24 inches of one another. If on the floor, the center M22 is merely 16 inches apart, but if the VP150 is sitting atop the TV the distance becomes closer to 28 inches. L+R panning probably would not suffer too much with such a large difference (VP150 on top of TV), but is the M22, alongside a L+R M22 as mains, better timbre-wise? Or is it all a wash?

The M22, as cente, in above post is to be vertically positioned by the way.

If I were to let my personal biases show about center channel placement, you may achieve a very smooth tonal match by placing an M22 vertically on the floor in front of the TV. The limiting factor here is the floor-bounce effect, which may yield some upper bass emphasis (you'd notice it on male dialogue--a slight warm, wooly coloration). Try tilting the speaker back slightly up towards the listening position to lessen any boundary reinforcement effect from the floor.


Alan Lofft
Axiom Resident Expert

Can anyone comment this, please:

"
The VP100 is a sealed speaker, while the M3 and M22 are ported. The VP100 uses a pair of 5.25" drivers and a 1" tweeter in a horizontal MTM (midwoof/tweeter/midwoof)arrangement.

The horizontal MTM arrangement is in general just a bad design choice for a horizontal centre channel. A vertical MTM arrangement has advantages. It limites vertical dispersion while still allowing good horizontal dispersion. When you put an MTM on it's side, then you get good vertical dispersion and limited horizontal dispersion. You want the good horizontal and limited vertical (you don't want sound bouncing of the roof and floor).

The larger problem though is lobing when you are off axis of the center. If you only sit directly infront of the centre channel (on axis) it won't be a problem. The further you go to the left or right of directly in front (off axis) you start to experience lobing. The crossover between the 5.25" drivers and the tweeter will be at a high enough frequency that the wave lengths the highest frequencies the 5.25" drivers produce will be shorter than the distance bewteen the two drivers. As you go off axis, the one 5.25" driver gets closer to you while the other one gets farther away. So the sound from the closer one gets to you before the other one. This is lobing and it is audible.

To solve this you need to get the crossover point to the midwoofs as low as possible and getting the two drivers as close together as possible. Neither of which the VP100 seems to do. The other solution is to use a 3way center, where there is a driver directly under the tweeter like a bookshelf and two woofers on either side.

A bookshelf center can't suffer from these problems. Plus a lot of people consider it the ideal to have identical speakers in every position.
"
( HTF)

A few brief comments for you on this post. The dispersion vertically and horizontally is not limited but rather is not linear horizontally in an MTM arrangement horizontally placed. The actual distance from your ear to the two woofers is not relevant in this equation but there is a cancellation that occurs as with the vertical axis response in a typical speaker array. The cross over point is going to have minimal effect on this problem. The trade off here is how to maintain a balanced left to right response while keeping the output from the speaker as close as possible to the screen. This trade off is addressed in our VP150, which does not have any cancellation off axis horizontally, is balanced left to right, and keeps the output close to the screen.

Ian Colquhoun
President & Chief Engineer