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K-77 Zee bracket drop in Machined Horn Lens


Dave A

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Panelhead has one of those motorboards for the  factory Zee bracket tweeters. The cutout is roughly 5.34 x 2.06 as he measures.This is the last configuration I believe left to be designed and it involved a rework of the cavity since it is larger than the regular small tweeter lens for the K-77 was. He is stopping by tomorrow so my intent is to have a set cut for him in Walnut. I would have liked to get the wood grain in the right orientation for the rendering but this program is a bit crippled since I am to cheap to spring for the full version but you get the idea. Top and side view gives you the dims and this should complete all variations. According to the number Claude has run for the small and large MAHL tweeter lenses without testing I expect this one to fall in between those two based on it's size.

 

Once again these have not been measured but the horizontal axis is wider as a proportion on these so I think it may well have better horizontal coverage than the other two. Again this is conjecture on my part and not measured data.

zee bracket wood.JPG

zee bracket side view with dims.JPG

zee bracket top view with dims.JPG

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DAVE if you ever need to borrow my Dayton Audio measurement microphone just let me know. I have two. One that is used on a iPhone or iPad and the usb one for the computer that works with windows and mac



Dollar for dollar Klipsch has no equals
Name one other speaker company that can build a speaker and keep working like new after 45 plus years of service. Answer NO ONE !!!!!!

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1 hour ago, Dave A said:

Once again these have not been measured but the horizontal axis is wider as a proportion on these so I think it may well have better horizontal coverage than the other two. Again this is conjecture on my part and not measured data.

Looks like a proper "tweener" to me. So there's good reason to believe that an overlap of the other curves and drawing a line between them would be accurate enough to judge besides hearing them, since the other two sound just fine.

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9 hours ago, carlthess40 said:

DAVE if you ever need to borrow my Dayton Audio measurement microphone just let me know. I have two. One that is used on a iPhone or iPad and the usb one for the computer that works with windows and mac

 Thanks for the offer Carl but I have a UMike and everything else needed to measure. I just need to get together with Claude and learn. I am getting a 150' cat5 cable in today for temp DSL to my shop so this week should see me get going on setting up and testing various things.

 

9 hours ago, ClaudeJ1 said:

Looks like a proper "tweener" to me. So there's good reason to believe that an overlap of the other curves and drawing a line between them would be accurate enough to judge besides hearing them, since the other two sound just fine.

My thoughts also.

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I have an example of an OEM Zee bracket and the newer K-77-F on hand to derive this new tweeter from. There are compromises made based on the hole size in the motorboard. Apparently the Zee bracket type was first and required a bigger cutout than that which followed which is for example the K-77-F. Now why in this day and time the cad file and cut file were not changed to reflect the newest tweeter I don't know since it is so simple to do. In any case this benefits anyone who has the later tweeters since I can cut a bigger horn lens with this bigger hole. The only difference of note are the screw hole placements which are different between the two. I have opted to go with the Zee bracket holes and it may require buyers to drill and use different holes that the larger spacing K-77-F's use. I may change this to a larger footprint and the bigger hole pattern in the future depending on what I hear back from buyers. I may end up cutting both sets of holes in there which is what i am leaning towards.

 

   Anyway here are some pics.DSC_0006.thumb.JPG.513b9ccc45b26ec1b1a5d17c525af788.JPGDSC_0008.thumb.JPG.7d677a1f405e6ee1ce86e81c3e060e1b.JPGDSC_0020.thumb.JPG.29c4221ad85d774a4b0db8954d3ddb16.JPG

 

  Here is a view of the zee bracket tweeter lens compared to the K-77 and K-79 types. The zee bracket lens is significantly larger than the K-77 lens.

DSC_0025.thumb.JPG.453cdab246761af20f4c2f6f21325d59.JPG

 

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  Installed the “drop in horns” and B&C DE120 compression drivers. I think if you put the horn in the freezer and tophat in an oven the horn might drop in. The fit is snug. 

  They are low hours right now, seem smoother than the K-77F. Think after 10 horns it might be even better. Looks are no question.

D81530B2-8F68-4C80-8304-37544B64B14C.jpeg

8FD99075-CD01-4C83-AF80-C47195DA59C4.jpeg

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Those are cnc cut motorboards so do you think a couple hundredths off top and bottom of the lens body would work? You got to be the guinea pig so this should be a one time event. I am also pondering a clamp that would use the two larger spaced holes we discussed to go over the ends of the lens flanges. Let me know if you want to try that. They ought to beat the pants off those K-77's when they are done breaking in.

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  No, think they fit perfect. They are just a snug fit.

  The K-77F was a loose fit. The K-401 flange pushes up. The laterally was just centered with a gap on each end. 

  The DE120 may be opening up after a little more play time. Played some tracks with brush work and high hats. From memory is is both more detailed and sweeter sounding.

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Hi Dave A

 

This is still Tractrix or something else? Some time ago for fun I modeled in CAD a tractrix horn with superellipsis shape at a mouth (kind of rectangle or square with round corners, depends on parameters). At throat its of course a circle (which is actually also superelipse). During the path as superelipse parameters are changing it goes from circle to almost rectangle. It was fun to go from math to cad model. Any way, while I was calculating it exactly for original LaScala cut out I was only able to produce model with horn length about 1 inch. I was little confused with one from top of this thread as it's 1,5 inch plus metal spacer between horn and driver. Then I realized that it's for z bracket version. But on last picture I also see smaller one in the middle. So any way, all of them are tractrix flares, right?

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4 hours ago, Bacek said:

Hi Dave A

 

This is still Tractrix or something else? Some time ago for fun I modeled in CAD a tractrix horn with superellipsis shape at a mouth (kind of rectangle or square with round corners, depends on parameters). At throat its of course a circle (which is actually also superelipse). During the path as superelipse parameters are changing it goes from circle to almost rectangle. It was fun to go from math to cad model. Any way, while I was calculating it exactly for original LaScala cut out I was only able to produce model with horn length about 1 inch. I was little confused with one from top of this thread as it's 1,5 inch plus metal spacer between horn and driver. Then I realized that it's for z bracket version. But on last picture I also see smaller one in the middle. So any way, all of them are tractrix flares, right?

I think what I do is far closer to a tractrix curve and not an exponential one. Perhaps one of the tech wizards here with more comprehensive knowledge of what each entails will chime in.

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  • 2 weeks later...
12 hours ago, brians7 said:

Dave A. The horns you made me fit perfectly and sound great. The black horns are Fastlane bought from ALK Engineering. Thank you very much Dave these fit right.

20190623_200831_resized.jpg

Good to hear and how many hours do you have on the DE-120's? They are nice drivers when fully broken in. That bigger lens cavity ought to help a lot too.

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