TMM vs. MTM.............

[Gavinator68]

I am designing a 2.5 system with the Peerless 830875's and Vifa XT25. Is there any difference between the MTM vs. TMM layout? What are your thoughts on this?

Cheers,

David

[mazurek]

If I understand correctly, TMM will give more uniform dispersion. And MTM will help minimize floor and ceiling reflections, possibly with wider dispersion, but narrower vertical dispersion.

I would state your application, as one layout would not be inherently better.

[LineSource]

Hi David,

From my understanding of 2.5 way speakers a

T
M1
|
M2
|
==
port

physical topology is fairly common, where the M2 is crossed in down at the baffle step frequency to cover compensation plus the lower bass. I've seen M1 in a separate sealed box volume and M2 in a separate bottom-ported box volume. The bottom port gets uniform floor gain and blocks any direct path to the ear of midrange leakage to help imaging.

A true 3-way TMW or WMTMW with larger diameter W has always sounded best to me. TMW wins clarity and detail. WMTMW wins imaging and weight.

[Gavinator68]

I will be using (2) of the peerless HDS164's and a XT25 in an ported arrangement that will still need a sub in the room for the lowend. The system will need to handle the front two channels of everyday stereo and some occassional HT. The room is a smallish living room with about 200 sq feet.

I was planning on using the HDS134's or HDS106's with an XT25 in a standard, ported two way configuration for small rear HT channels in the future.

For the front channels I was thinking that paralleling the (2) HDS164's in a 2.5 way would make things easier by bringing the 8ohms of the HDS164's down to match the 4ohms of the XT25. Am I missing a more important benefit of crossing them over seperately? I want these to have as much detail and quality imaging as possible.

Am I expecting too much?