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Dave A

Super MWM

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Looking at a set of MWM plans the other day got me to thinking about why did Klipsch limit the depth to less than 48" which was the width of a standard sheet of plywood. I had no idea what percentage of these were for theaters where space was a problem and how many ended up in places where outdoors or in big arena settings space would not be a problem. So they made a decision based on space restrictions I figure. My thought was what if one designed this around a 5' x 5' sheet of Baltic Birch and I did so using the same exterior dimensions at the front and back. This meant that the horn would be 60" deep and still 67.75" wide leaving two small sections to be added on to complete the shape. I had no good way of doing so at that time but modeled it that way and then also modeled it for the 60" wide sheet which would cut off some of the front width.

 

  In the mean time since Claude was kind enough to send me the set of drawings for the MWM I figured he would like to see what I was thinking of doing. He ended up providing technical assistance to interpret the results of what I proposed to do and validated that the idea had merit and added to it with suggesting adding back chamber space which improved it. He also came up with the Super MWM moniker so we have the Super Heresy and Super MWM's to play with.

 

  There are three iterations of this. One as shown below. One with the back center triangular guide like the La Scala with the addition of two corner pieces also. Then finally one that can be made without adding to the sides of the 60" wide sheet. If anyone is interested I can provide line drawings of all three. Now in regards to adding onto the length of a piece of plywood here is a way to easily and securely do it.

 

http://www.rockler.com/finger-joint-router-bit#turnto-reviews-content

 

  Some comments from Claude regarding these.

 

 "6 db down at 32 Hz. -10 at 30 Hz. so yes, it's definitely usable. Had a higher peak 38 Hz. and a dip between it and 100 Hz. until I opened up the space in the triangle. The it flattened out like a pancake. You got the final version. I even tried other woofers, but the K33 is the winner. I think a Crites woofer would do just as well or better."

 

Regarding the idea of using 60" wide instead of adding wood to get to the 67.75" wide. Considering the above mentioned way of finger splicing wood I do not intend to build just 60" wide ones for myself.

 

" It's volume is more important than the small percentage of mouth area it adds with the taper. Also, the Crites woofer models the same way with about 1/3 of a db more output at 400 Hz. BTW this horn is way more flat magnitude response than the Khorn, Jube, or LaScala ever were."

 

Really like these double MWM bins and the idea I can go lower like this greatly interests me and these will be the first speakers I actually build. Maybe if I actually get to the Klipsch gathering next spring I will bring a set to listen to.

 

 

 

basic top view.jpg

MWM theoretical results.jpg

top view with added back pieces.jpg

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As an addition the plans can either be the .709 or 18mm Baltic birch thickness or the .75 standard plywood thickness. Contemplating doing these in 25mm Birch also for the outside pieces. I bought a Speakerlab Khorn the other day for the heck of it mainly because I wanted to see how tough it would be to build. Complicated like the plans I have seen for other things. Since I have the space these MWM's are dirt simple by comparison and I figure a good skill saw with a clamped on guide + a good 1/2" router is all one needs to build this.

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What ever you have
Do you have a list of drivers that may work in it or the specs to look for so maybe I would be able to find a driver from parts express
Thanks

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OK I have a trip to make so it will be a couple of days before I post the plans. I have 3D CAD parts done but need to generate the drawing from them. Claude says the K-33 woofers are the ones or Crites version of those. The object here was more bass and the K-33 beats the K-43 just to head that question off at the pass.

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I have always preferred and used K33s over K43s in my MWMs............but I still use subs.  Would be nowhere without subs.  That's just me.

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The mouth braces look off to me.  If you keep the front of the brace where it is, the rear of the brace should be in a straight line that ends up in the center of the space of the horn mouth at the rear of the cabinet, if that makes sense.  That would swing the rear of the braces outward slightly from where they are now. ( EDIT, it looks like the fronts should go inboard as the rears look centered. ) I wouldn't think it should be parallel to the outside wall.

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Since size isn't a limit for you, Just build a straight horn.😋

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The beat goes on...  ^^^^^^^^^^^^   😎  Can't wait to see what actually transpires  though...  Sounds very doable...

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Is your sealed woofer chamber volume the same as an MWM or bigger?

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1 hour ago, jwc said:

Is your sealed woofer chamber volume the same as an MWM or bigger?

Since I did the Hornresp model, it's definitely Bigger and prevents a 3 db hump at horn cut off and gives a few Hz. extra extension.

I also have a new mod which extends bass further with outside dimensions like Dave's first one above.

Now these are frikkin' huge and not for the squeamish. However, if you want bass that's much smoother, then you need a horn with the fewest folds, like this one.

SuperMWM2.jpg

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The original mwm calculates as annul 50 Hz with K33.

 

 

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On 6/18/2018 at 1:08 PM, jwc said:

The original mwm calculates as annul 50 Hz with K33.

 

 

Well, we are going for 15 Hz. lower than a standard MWM, the goal is to get to 30 Hz. Vs. 45 Hz. for the MWM. With bigger rear chamber and much longer horn. BTW (9 feet long vs. 6 feet long), check your Email on the other matter.

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15Hz?  OMG.  And play out to what frequency?    15Hz to 400Hz....  Has that ever been done horn loaded?

 

 

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I just wanted to add that the curve shown is based on being forced to put these in corners because, where else would they go being to big?? It's also based on a K33 with 2.83 volts input, which is somewhere between 1 1/2 to 2 Watts of power. 115 db of bass is rock concert level, so you could drive these, like I do my Jubes, with a $25 Texas Instruments based class D chip amp for about $40. Big horns and small amplifiers rule!!!

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4 minutes ago, jwc said:

15Hz?  OMG.  And play out to what frequency?    15Hz to 400Hz....  Has that ever been done horn loaded?

 

 

-6 db from 30-400. You could do a Data-Bass Gjallarhorn for 15-30 Hz.

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OK.  30-400.  That is doable.  I would wager ....just a guess..... that the output will drop noticeably under 35 Hz.

 

Everybody wants a sub these days.  Do a big straight axis to 50Hz then let that horn sub do the rest.

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23 hours ago, Dave A said:

Really like these double MWM bins and the idea I can go lower like this greatly interests me and these will be the first speakers I actually build.

 

 me too. I was going to do MWM's and then you guys come up with this.  

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