Modula MT-XE - You didn't ask for it... it's coming anyway

[JonMarsh]

Correct. ThomasW felt that Modula MT MkII wasn't descriptive enough about the difference between the original and this version After a little thought, (about 26.87 nsec) I concurred with the suggestion.

We could make them even more extreme, but I figured you've gotta draw a line in the sand somewhere...

[numberoneoppa]

Uh oh, how about the documentation? Oh, and of course, your signature.

=)

[JonMarsh]

The documentation (PDF) is posted in the Missions Accomplished reference thread, as well as recently in this thread. But much easier to find in the MA thread, which will be updated with a little bit of overview stuff. This thread has wandered way, way off course too many times to be transferred to the MA section. :W

[Ray Collins]

Jon,
Isn't it a two way design?


Modula MT XE PDF

"I'll highlight some of the key aspects of this waveguide loaded three way, but it's just an overview"

Ray

[JonMarsh]

Yes, the Modula MT XE is a two way design.

But the Modula Xtreme TMWW is a three way.

Heck, maybe I just ought to call them "Little One" and "Big One". :W

[Ray Collins]

Call them anything you like. If you get to the Gulf Coast I will buy you some of the best seafood available anywhere as a thank you!

Ray

[JonMarsh]

Thanks for the kind words, Ray- about the closest I get to you is Houston on business! (HPQ (HP/Compaq)). I bet it's starting to warm up fairly well in Mobile by now...

[Ray Collins]

I am shooting in a Trap Tournament tomorrow and will be wearing shorts and a golf shirt...

Ray

[JonMarsh]

Figures! (though I lived in Colorado a long time and for me, 55 degrees is enough to break out the shorts...)

Alas, today I am working on a standaby/low power mode power loss analysis and design corrective action presentation for Flextronics that has to be pretty much ready by Monday morning, so not much weekend for me. At least it's a Marketing suit that's going to fly to Dallas to present it later in the week; he'll be my sock puppet.

[---k---]

Yesterday was mid-60s here. I came home and it was so nice that I just sat out on our patio and read for about 30 minutes. This morning it is snowing...

[cjd]

Guess I won't be doing any measurements outside today! Over an inch of snow already!

Wheeee.

[JonMarsh]

Yeah, I've had similar problems the last few weeks with rain preventing me from setting up power tools and saw on the patio. This week, work is the problem!

Well, it will warm up for you eventually, Chris.

[Bear]

Since I haven't said it before (in this thread), Jon -- very inspirational and nice work!

[JonMarsh]

Attention Please!!

Please, no more off topic posts in this thread- discuss other designs, like the pending Modula Xtreme, in it's own thread.


Thanks!

~Jon

[Face]

For those looking for LBL, K-Mart has a decent selection of Bamboo cutting boards up to 24" in length.

[JonMarsh]

Nearest ones to me are about 30 miles away; the one in town closed about 10 years ago.

[dwk]

desktop application?

Jon,
I have a couple questions on the XE - I hope staying on topic wont' get me shunned :-)
I'm actually pondering whether these would be viable as desktop/computer speakers in a nearfield setup. They may simply be physically too big, but a quick check with a tape indicates that they are more or less incrementally bigger in each dimension than my existing Tannoy System 600's, so it might work. I'll have to put together a cardboard mockup.

However not every speaker works nearfield, although most 2-ways can be made to work. So...
- what is the design axis? Is it on-axis with the tweeter? The followup is what is your take on 'integration distance' - might it be workable, maybe with a bit of backwards tilt?
- would you forsee any need to lean out the bass any further in such nearfield setup given that it would be rather close to walls? If so, would this basically be a slight reduction in L1 accompanied by tweaking R4 to rebalance the tweeter level? I have measurement and eq capability via the computer playback chain, so this is probably not a big deal.
- did you spend any time considering a sealed alignment? I may have a sub in the picture, and sealed may save considerable depth in the cabinet.
- uh, whatever else I'm not thinking of......

It may be the case that something like Mark K's ER18-DXT might be a better fit (literally), and would be cheaper, but this seems like a more interesting project if the size works out.

thanks.

[JonMarsh]

Jon,
I have a couple questions on the XE - I hope staying on topic wont' get me shunned :-)
I'm actually pondering whether these would be viable as desktop/computer speakers in a nearfield setup. They may simply be physically too big, but a quick check with a tape indicates that they are more or less incrementally bigger in each dimension than my existing Tannoy System 600's, so it might work. I'll have to put together a cardboard mockup.

However not every speaker works nearfield, although most 2-ways can be made to work. So...
- what is the design axis? Is it on-axis with the tweeter? The followup is what is your take on 'integration distance' - might it be workable, maybe with a bit of backwards tilt?
- would you forsee any need to lean out the bass any further in such nearfield setup given that it would be rather close to walls? If so, would this basically be a slight reduction in L1 accompanied by tweaking R4 to rebalance the tweeter level? I have measurement and eq capability via the computer playback chain, so this is probably not a big deal.
- did you spend any time considering a sealed alignment? I may have a sub in the picture, and sealed may save considerable depth in the cabinet.
- uh, whatever else I'm not thinking of......

It may be the case that something like Mark K's ER18-DXT might be a better fit (literally), and would be cheaper, but this seems like a more interesting project if the size works out.

thanks.

Well, let me take a shot at answering your questions- hopefully it will help, no guarantees, though! :W

The design axis is centered on the mid to tweeter. Because of the waveguide, the acoustic offset of the woofer and tweeter are pretty similar. That said, going above the tweeter axis too far will start to produce a dip in the crossover region due to the phase difference. The ideal way to make a nearfield monitor is a sloping face design, if you intend to set it on the table- at least that's my opinion. I'm used to more thinking in terms of nearfield monitoring in a studio, where one could put the monitors just above the top back ledge of the mixer.

The integration distance on these is pretty close- the measure fairly well at just 20" or so. It's not like a big three way in that regard. Because of the acoustical offset matching and the low order crossover, and lowish crossover frequency (about 2 kHz) it's pretty well behaved.

Now, my experience is that, possibly because of the off axis power response, these sound pretty good even near boundaries, and are not what you'd call heavy or dark in that mode- that's kind of how they're setup at the "Outlaws", just on a media shelf unit flanking a flat screen TV, pulled towards the front. I'd experiment with the design as is before considering retuning it, if you go down that path. ("Outlaws" are my ex's oldest sister and her son, who's disabled from a diving accident years ago). It's probably too bad I didn't get to keep them and play with them a bit in different locations before delivering them.

With a different woofer I might have considered a sealed alignment- the ER18RNX has a fairly low Qts, and I don't think it would work out too well that way as a small full range sealed. I was building it for folks who likely would be using just by itself for a while, so having a little bottom end and extension was desirable. Sealed could save depth in the cabinet, but then it would be a little trickier finding room for the crossover.

The whole reason the project came together was their need and me having the parts and some ideas kicking around for a while- it gave me a good excuse to try it out.

You may be right, for a sort of desktop speaker, I can imagine Mark's DXT might be just the ticket size wise, and certainly would be a bit simpler to build. We should be able to compare them in the Northern CA DIY meet the end of April.

I do really like how the D2608 mates up with the waveguide, got the Xtremes coming together nicely with the same tweeter crossed just a bit higher. It does work well in the MT XE's, Cheryl commented several times on how even placed in the family room area, they sounded pretty nice in the living room. Possibly the waveguide helps with both dispersion enhancement and limiting destructive diffraction, though as Mark likes to put it, the situation is "murky".

[dar47]

Inside diameter of the H-65 waveguide.

John thanks for the design, I think I have my 2-channel speaker for the living room. I'm thinking of doing this with a 1 1/2" Bamboo baffle milled and was wondering if you measured the inside diameter of the waveguide. I got Zaph's profile but he has milled to match the Seas tweet and the profile doesn't extent to the 1 1/4" required thickness to match the D2608-9130. I can project with Solid Works but it would be nice to compare.

[JonMarsh]

you can just match to the inside diameter of the tweeter front plate, which is 1-11/32". If you're feeling a little loose, just use 1-3/8". :W If you're milling per his DXF file, use the opening to judge, it's possible the curves don't match exactly between the hardware and his drawing.

I'd be curious to see a picture of how your milled waveguide turns out! There's some guys that have been milling some pretty nice wooden waveguides over at the Lansing Heritage forums. Ones more like the DDS-1.

[dar47]

Thanks, I'm just avoiding ordering from another place to get the waveguide to compare and that profile is getting sharp fast the last bit to the inside diameter. I'm put these on stands in a large great room, dining room, and kitchen area that is vaulted. Would you say they have a good vertical listening window as when your walking around?

[dar47]

you can just match to the inside diameter of the tweeter front plate, which is 1-11/32". If you're feeling a little loose, just use 1-3/8". :W If you're milling per his DXF file, use the opening to judge, it's possible the curves don't match exactly between the hardware and his drawing.

I'd be curious to see a picture of how your milled waveguide turns out! There's some guys that have been milling some pretty nice wooden waveguides over at the Lansing Heritage forums. Ones more like the DDS-1.

Yes I will post some pics of the baffles when I get there. I'm rushing my son who is writing exams to get a quote from his guy before my son leaves for his summer Engineering job in Alberta. Here is a profile to match the D2608-9130.

[dwk]

Well, let me take a shot at answering your questions- hopefully it will help, no guarantees, though!

Thanks Jon - it does help, even if in the end things remain somewhat 'murkey'. I have lots to mull over in terms of my available time and system goals. I've managed to massage my existing desktop system into a form that is satisfying for the short term, so I'll digest things for a while and go from there.

[JonMarsh]

Sounds like a plan- maybe I'll get far enough along this year that I can do something dedicated to my desktop situation for monitoring on my DAW setup. With the size of screens I have, I think I'd have to hang them on the wall. Maybe something weird with slope baffles merging to the wall at 45 degrees, or a down titled waveguide baffle? Hmmmmm. Might be a little weird... :W

[dwk]

Maybe something weird with slope baffles merging to the wall at 45 degrees, or a down titled waveguide baffle? Hmmmmm. Might be a little weird... :W

Well, now you've gone and done it. At the risk of heading way OT only a few posts after the mod nudge, you're touching on ideas that are at the root of why I was looking at the XE in the first place....

I've also looked at the desktop situation with all the flat surfaces and thought 'waveguide'. In fact, since I have the U15's I of course go farther and think of a Unity/synergy arrangement. If you're willing to live with tweeters placed on the desktop, I think this is a pretty straightforward idea - the monitor forms one side of the waveguide, the desktop a second and you're left with the question of how to complete it - if you want a 3-monitor setup you can use the 2 flanking monitors as the other sides. Otherwise you'll need wings of some form either formed by the walls or via panels.
The idea with this waveguide is basically simply to avoid reflections rather than to improve loading or efficiency - it places all drivers 1/4 wave or less from all boundaries over the operating bandwidth, which means they'll acoustically couple rather than reflect. If you also throw in keeping the drivers 1/4 wave apart at the xover freq, you end up with the Unity/Synergy arrangement.
FWIW I've also been thinking along these same lines for a corner-mounted HT speaker. The big problem is that this almost certainly has to be a 3-way to be able to keep things 1/4 wave or less from boundaries over the full bandwidth and a 3-way is almost impossible to do small enough to go into corners without looking visually dominant :-(. It maybe possible to get away with something like a small woof and the FR88 and no tweeter since the beaming won't be as big a problem due to the constrained radiation angle, but you still will probably face some comb filtering in the treble.

Anyway, these are obviously longer term experimental ideas, and so I 'need' something simple and straightforward in the interim - hence the idea of using the XE. Unfortunately, I think the XE is still far more of a project than makes sense for me at this point if I'm relying on it to be a main part of my system in the near-term. Fortunately, I pulled in my old ProAc Super Tablettes out of the dining room and set them up as nearfield monitors and they're sounding pretty darn good - slightly hot on some recordings but since I'm using a PC as a source a bit of EQ is easy enough to add.

Anyway, this is way OT and if you want to cut this out and put it in the theory/design forum it would probably be more appropriate.

[JonMarsh]

No problems- it's related or derivative of the original project. We have a "closed" project thread up anyway in the Missions Accomplished area, this thread has wandered so far afield at times that your questions and comments are barely off course from the main topic! :W

[spadez]

Hi Jon,

Have the Xtreme (SO) design had any loving recently? Also, is this the correct thread to ask? I'm a bit confused!

[vellupiri]

Do this WG thing intrest you anymore, zaph?

How's your Finnish, John? My Finnish is pretty rusty... I have a few Swedish friends in Austria (I know, that's weird in an of itself, but it's work related), maybe I can get them to check this out. If they're setup to ship in Europe (highly likely), that's a possibility. Price isn't high, but taxes kill you over there!

Maybe I can help!
I do speak Finnish

VP

[JonMarsh]

Hi Jon,

Have the Xtreme (SO) design had any loving recently? Also, is this the correct thread to ask? I'm a bit confused!

The correct thread would be the Modula Xtreme thread. This is for the small two way.

Regrettably, I didn't have any weekends off between around July 4 and the end of September, so even the planned updates for the main version of the Modula Xtreme have not been completed. And since you shifted your interest to the RS based system, no one else had an immediate need, so the Modula Xtreme SO has been "on hiatus".

Which is not what I'd like, but work has been bonkers. Now there is some agreement that I shouldn't be working for three different divisions, and they should hire someone else, and that 170% utilization is not a reasonable work plan. So things are getting better, and I hope to get back to these key projects, as well as a cooperative upgrade to the Modula MT XE design for one gentleman (Illuminator woofers with waveguide milled into panel), and my further investigation for the Modula Xtreme with Janten waveguide and Ciare MT320 tweeters (all sitting around here for months), and a new cabinet rebuild (most of the key parts for that on hand and collecting dust.)

[kvardas]

...and don't forget the M8td3. :B

[numberoneoppa]

Stop slackin', Jon. :P

[Hdale85]

Yeah, he acts like there aren't 100 hours in a day? His work place obviously knows there is, now why hasn't he figured it out :B

[dar47]

Nice Illiminator woofs, Maybe someday a 3way tower with wave guides and a matching CC. Sorry I'm day dreaming again.

[Hdale85]

I love your baffle though....

[dar47]

I love your baffle though....

Thanks, it's Jon who hit one out of the park with this design. Maybe the changes to the RS drivers will spur on some new designs and this vary musical concept would fit so nice into a theater package.

[JonMarsh]

I love his baffles, too, and in cooperation with another forum member, we may do a similar design with the paper illuminator woofer and one piece baffle/waveguide; he'll build, I'll measure and design crossover.

Also, the aluminum illuminators will be tested in the Ardent soon...

Yeah, I've been trying to dig deep and find those one hundred hours a day, sure could use them, especially now since I've met an interesting lady a few weeks ago- complicates things even further!

[JonMarsh]

Even thinking about a 2.5 way with the paper illuminator for the "mid" and the aluminum for the 0.5 way... not sure about the tweeter, but it would be a lot faster to build wiht the Jantzen waveguides and Ciare MT320... gotta test that combo out!

[Hdale85]

Ah the idea's never end! I'd say you dream up probably 5x the projects you complete per year.

[sdl2112]

Jon, thanks for taking the time out of your busy schedule to reply. The least I can do is share some motivating material.. I tried a different approach to the interface of the H-65 and the D2608, I knew my gasket would look like....well...like I made it. I wanted to get the throat closer to the dome. I just did it last weekend and haven't taken any measurements. My computer died a while back and I'm still installing things on the new one and no thanks to Windows 7

Anyway, on to the photos

Cutting the D2608 faceplate with template guide




four 4'x4'x1" sheets of bamboo plywood

[dar47]

Nice job on the clearance. All that nice bamboo in 1 place, are you making the cabs out of that?

[Hdale85]

4 sheets of bamboo ply is expensive My buddy bought 4 sheets for like 700.

[sdl2112]

Yes I plan on making most of the cabinet from the bamboo. To me it makes the build easier. My sheets were cut in half before delivered so I bought only 2 - 4x8' pcs.

[benchtester]

...I just did it last weekend and haven't taken any measurements. ...

Cutting the D2608 faceplate with template guide

I did something very similar. I cut the counterbore in the face plate to 2.008"/2.005" diameter; and .178" deep from the front outside edge of the tweeter face plate. The ribs to the waveguide were cut away from the O.D. of the throat and to an equal depth (.178"). It centered very well on the molded O.D. of the waveguide. I'll publish clearer drawings in the next week or so.

Your project is off to a great start! :T

[JonMarsh]

Interesting- looks like you're on to something! Have to be sure I understand what you're doing- more pics?

[benchtester]

Interesting- looks like you're on to something! Have to be sure I understand what you're doing- more pics?

Here is a link to some bad cell phone pictures.

















I have to run now but will explain more later.

One can see how the tweeter is recess-mounted in a piece of MDF. The waveguide is mounted on the front baffle in the normal fashion. When the two pieces of MDF are bolted together, the waveguide is held against the tweeter face plate counterbore. The tweeter and waveguide are held concentric by the boss on the back of the waveguide and the counterbore on the tweeter faceplate.

One additional advantage is that the waveguide can be sealed from the main cabinet volume.

BTW: sdl2112 did a real nice job of mating the pieces. His looks closer axially than mine, and he did it with a router. I had the use of a mill and rotory table, but a metal lathe would work well too.