[Christof]

I'm in the process of working designs for a new pair of mains.  I will be using stereo subs with twin Adire SX 10's  with these mains.  I was thinking about a wmtmw using Seas aluminum 10" W's but this seems pointless since I've decided to use the dual subs.  I would like to keep drivers under $1k.  I am partial to the Seas Excel but chose not to use it with wmtmw design to keep costs down.  Since I'm leaning away from this I can now put Excel back into the equation.  I will consider anything.
(I have looked into the Odin MK3 from Mad...a definite possiblity)
 
My listening room is 12' x 20' x 9'ceilings.   I listen to Acoustic music, classical guitar, vocals...at loud volume levels, rarely do I play music with overdriver electrical instruments.  I would like to incorporate my mains into a future HT system which will be used 1% of the time

I'm a cabinet builder so cost is no object on enclosures.   I'm just looking for ideas to help get the ball rolling.

Thanks alot you guys
Christof

[Jon L]

I'm in the process of working designs for a new pair of mains.  I will be using stereo subs with twin Adire SX 10's  with these mains.  I was thinking about a wmtmw using Seas aluminum 10" W's but this seems pointless since I've decided to use the dual subs.  I would like to keep drivers under $1k.  I am partial to the Seas Excel but chose not to use it with wmtmw design to keep costs down.  Since I'm leaning away from this I can now put Excel back into the equation.  I will consider anything.
(I have look ...

That's just crazy.  The chances of starting from scratch, selecting the right drivers, building the right cabinet, and most of all designing/tuning the VERY complicated crossover necessary to end up with a great sounding WMTMW speaker is rather slim.  You may end up tweaking and tweaking forever, perhaps even years.  Unless you are a master crossover designer, I wouldn't go there.  

Since you already have 2 subwoofers, a more sensible approach will be to go with monopole planar magnetics.  Get the BD 75 or 60 planar magnetic ribbons (or get the "improved" Carver planar magnetics from Audia), get a digital X-over/EQ (from Behringer or dBx) to straighten out the bumps in the ribbon and to cross over to the subwoofers.  This type of planar magnetic drivers will play VERY loud if fed with a lot of power.  You have a LOT better chance of having a great-sounding speaker system this way than to reinvent the wheel (a complicated wheel at that..)  Just IMHO.

[JohnR]

I am partial to the Seas Excel but chose not to use it with wmtmw design to keep costs down.  Since I'm leaning away from this I can now put Excel back into the equation.

The Ellis 1801 sealed might be a candidate, as might the new design Rick Craig has done with the W18 and Millenium:

http://www.madisound.com/cgi-bin/discuss.cgi?read=291443

They both have circles here.

[Figo]

I second the 1801.  world class drivers, crossover, and cabs for something like $850 with a decent veneer(you build cabs)

[Christof]

I do have a couple people who are, imho,  very good at crossover design that are working with me on this project.  I have ruled out the wmtmw as I said in my earlier post.  I have heard nothing but praise for the 1801. However, I was thinking of an mtm using the Seas Excel line.  Basically looking for ideas on T's, probably a dome to widen things up a bit since I entertain often and we cannot all fit into one listening chair.  Once I have the drivers selected a designer I'm building cabs for will build the test box and crossover.  I do realize that this could be an endless tweak session but isn't that what it's about?

thx...Christof

[warnerwh]

The endless tweak session on your self designed speakers could run into hundreds of dollars worth crossover parts that you'll never get your money back out of. Try the DIY forum at Parts Express. Lots of friendly experienced people there. I had a clue of how complex speaker design is but after talking to an engineer and buying Vance Dickason's book I decided to end that idea.  Beginners should start with a simple two way.  If you have a speaker engineer to help you then you have a chance.  Ask around, speaker design is much more complicated than most people realize.  Also crossover parts are spec'd one way but measure another.  Theory may look right but your ears will tell you something is wrong.  I was told it would take years of doing simple projects to be able to try a speaker like I was thinking of, which was a pretty complicated 3 way.  If you choose to take this mission remember it's your money and you could spend alot and end up with a bunch of high quality parts that sound like a Bose speaker.

[JohnR]

Er, well, he did say "I do have a couple people who are, imho, very good at crossover design that are working with me on this project."

Christof, the safest bet would presumably be to go with the tweeter that others have paired with the Excels. The Hiquphon and Millenium seem to be the popular choices. I've heard sfdoddsy's speakers which are an MTM using the Excel and Millenium (I think... ?) and they were very good, although a major difference from your idea is that they were dipole.

[gidappa]

Hi all!

I think its always fun when someone wants to build a new design rather than just follow in someone elses footsteps.

New design based around Excel woofers in a MTM config and trying to find a decent tweeter?

First. A speaker in this config introduces a new set of problems, especially in the vertical plane. To reduce the problems you need to cross the tweeter low(around 2k), but that should have been the plan from the beginning since the Excel driver start breaking up quite low anyway.

On the plus side you will get is a very stable "frontloob", while for example the ceilingreflex will be somewhat colored. Powerhandling and sensitivity also goes up to a nice level.

You could start with a crossoverfrequency around 2.2k, partner the Excel woofers with a truly great Aluminumdome from Seas, the H534.
Make sure your "crossoverguys" truly understand phase and why the tweeter must be cut off steeper than the woofers. Try to get 4-order (acoustic!)slope on the tweeter(which (probably)means a second order electrical slope.

Good Luck!

[Duke]

Hello Christof,

One of the characteristics of an MTM is that the radiation pattern of the two M's is narrowed in the vertical plane, and this becomes significant in the crossover region.   If you use a single dome tweeter, then the tweeter's pattern is much wider in the vertical plane than that of the two midwoofers.  

By using two tweeters in a vertical array, as does Dynaudio in their most esoteric systems, the vertical radiation pattern of the tweeters matches up better with that of the midwoofers.  

This matters because your ears derive timbre not only from the first arrival sound, but also from the reverberant sound in the room.   Ideally the reverberant sound will have approximately the same tonal balance as the first-arrival sound, and the way to get this is by keeping the radiation patterns as uniform as possible.  

The improved power handling provided by the second tweeter may make it possible for you to get away with a first order crossover - see Roy Johnson's excellent posts in the "First Order Crossovers" thread.

Another way to get good vertical symmetry is to use a ribbon driver in an MRM configuration.  A ribbon's radiation pattern is inherently broad in the horizontal plane but narrowed in the vertical, and so would match up well with the radiation pattern of the two midwoofers.

If you are bound and determined to build an MTM, you might consider angling the top midwoofer up by 20-30 degrees, and the bottom one down at the same angle.  This will give a broader vertical pattern to better match up with that of your single tweeter, while still maintaining the concentric geometry.   This might be called a "splayed MTM".   Note that a crossover voiced for a regular MTM will probably need to be adjusted on account of the reduced on-axis SPL of the two M's up near the crossover, but once adjusted the timbre would probably be a bit better because you wouldn't have as much of a dip in the reverberant field response.  

Best of luck with your project!

Duke

[Christof]

Duke and everyone who contributed to this thread,

Thanks for the design info.  for the time being I'm going to build a pair of arrays with Rick Craig.  I may still do a wmtmw design but after reading all the positive comments about arrays I could not resist.

Chris

[rosconey]

very smart move-rick is a great guy to deal with, he designed my speakers