MAY 2004

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PROJECT MAY
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May 17 - TimG

I had the MTM set up in a larger room and we listened to a wide variety of music with the 800hz crossover. We listened to some Copeland, and even my wife was impressed, now that's saying something. When you sit in the sweet spot they sound incredible, and they sound good when you stand up as well. I also set up the system as a TMM but haven't had time to do any in-depth listening tests. I've been working on other things while I wait for the horns to arrive.
 

 


May 20 - Mr. Widget

The horn prototype is now complete. As you can see I have sealed the MDF as the raw MDF was very soft and fuzzy even after sanding. I was concerned that it could affect the sound as I have been told that a smooth finish versus a rough one can make audible differences. This MDF horn is in halves that screw together. If I leave it as is it can be disassembled and molds taken off of it if members wanted to cast fiberglass copies of it. Due to negative draft in the design, a mold will not be possible if I glue it together. If it is glued together I can massage the seam. As it is now there is a noticeable seam, but I doubt it will affect performance (you know like those dented dome tweeters on eBay ) Seriously, I don't think it will affect performance... but those with bat hearing might ... I doubt it.

All that is left is the fabrication of the driver mounting flange.


Shot 1 Illustrating Assembled Horn


Shot 2 Showing the Two Halves.
 

 


May 21 - Mr. Widget

I started laying out and machining the mounting flange earlier this evening. It will be made of 0.25" aluminum plate that bolts onto the driver with flush screws and then gets bolted to the rear of the horn as seen in this earlier illustration. There will be a 2.5" hole in the plate that allows the machined wooden horn throat through to mount flush with the driver. (This will make sense when I post a photo of it.)


 

 


May 21 - Mr. Widget

I will ship to Tim one 435Be driver and one 045Be driver with it's plastic horn with my MDF horn. Tim should be able to rig the UHF horn/driver to the top of the MDF horn with modeling clay and foam core to position it and simulate a baffle. This should allow various position tests.

I expect the final solution to look something like the illustration below. It is possible that we will change this based on Tim's findings.

Tim should feel free to run the sides of the MDF horn through your table saw if he wants to see if the extended sides affect the sonic performance. For this first MDF horn I continued the sides along the radius of the front lip of the horn, but I am not expecting this to be the ultimate design solution.



 

 


May 24 - Mr. Widget

Ok, here at long last is a finished MDF prototype horn with mounting flange.

BTW. It is not my fault that the driver is rotated... for some reason JBL drilled their holes a few degrees off normal. I didn't realize it until I mounted the darn thing and I have already made both mounting plates.

 


Here is a view of the mounting flange and horn back before mounting.
 


And the view from the front.

 

 


May 26 - Giskard

A pair of stock JBL Sonoglass H9800 horns are shipping from JBL for prototype development courtesy of Paul Bente and Greg Timbers. I cannot thank these gentlemen enough for their continued support with this endeavor!