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Chris A

A K-402-Based Full-Range Multiple-Entry Horn

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Hi Chris. 

 

"Glad to hear the extra length of my CD s not a problem."

 

Hmm. It might not affect the right placement of the woofer-ports in regard to hornflare (geometry), but how about the upper usable frequency range of the woofers?

I would have thougt that the 1/4 wavelenght cancelation notch frequency is a reflection dependent on the depth of the compressiondriver!? And that that again will affect the upper usable frequency range of the woofer, and introduce the need for an other crossower-frequency/crossower -layout!? Hope I did manege to explain it right?

 

Steffen

 

Steffen

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10 hours ago, Supersteff said:

I would have thougt that the 1/4 wavelenght cancelation notch frequency is a reflection dependent on the depth of the compressiondriver!?

I recommend trying it out yourself: try TAD TD-4002s and then a K-69-A (or similarly shallow throat 2" compression driver) on a K-402-MEH horn.  Also, read the reference that I provided (Huygen's principle).  Ask yourself: at which point does the backward-traveling wave reflect?  Off the phase plug? (No. Before that point--at the first impedance discontinuity it encounters.) 

 

Then we can discuss the point...much more succinctly.

 

Chris

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On 5/22/2020 at 4:02 PM, rickmcinnis said:

Thanks, Chris A.

 

Glad to hear the extra length of my CD s not a problem.  I had remembered your mentioning you had used your TD 4002s and those would probably have an even longer distance with the adapter required to fit the two inches diameter entrance but I would rather know than "find out" the hard way.

 

Yes I knew I would need to chamfer the ports to have as short a wall as possible.  Do you continue the chamfer to the K402's walls - seems like it would be easy to make a very sharp edge with that plastic.

 

Should one chamfer the side facing the cone with a "quick" chamfer or make it as long a smooth transition as possible?  Should one attempt to fill the area between the mounting plate and the cone?  Seems like this could be a good thing but difficult to balance with the ports requiring a small volume.  This is more of an afterthought.

 

Sounds like you are adamant that a good piece of plywood is sufficient for the woofer mounting.  This is welcome news.  That lexan is expensive.

 

I know you had the benefit of using the KLIPSCH box.  I will have to make one.

 

A few questions concerning the box's construction.

 

1.Are you doing anything unusual to seal the mouth of the horn to the box?  I figure some kind of dense foam gasket will be sufficient?

 

2. I assume you are not hearing any noises from the box.  One wonders if the two woofers tend to eliminate some box problems - kind of like djk's PPSL bass cabinets?

     a.  Did you add any bracing to the box?  Are you hearing any need to worry about adding bracing?

     b.  Did you add any damping to the walls of the box like bituminous felt pads or something like that?

     c.  Are you doing anything to connect the walls of the horn to the box?  Do you see any advantage or disadvantage to attempting this?  Would there be any advantage to                  damping the walls of the horn since the ones I am getting is the lightweight version?  Again thinking of those bituminous felt pads the Brits like to use.

 

I will be using two of these in a music system.  I will not be asking them to go below 100 hertz.,  I am hoping this will minimize many potential box problems by  reducing the pressure on the walls of the box. 

 

When I get ready to cut the ports I am going to send you a picture of where I plan on placing them and asking for your approval.

 

I have a few weeks of box making ahead and getting familiar with the horns AS IS.  I have yet to receive them.  Cannot wait to hear how they compare to the INLOWs.

 

Now to find someone who would like to have a pair of the INLOW horns.

 

Got the CRITES woofers.  Compared to the monstrous GREAT PLAINS 515ghps they look like toys.  Sure like the fact that they do not weigh what those 515s weigh!

 

Anyone know anyone who wants a pair of 515ghp woofers?

 

THANKS, again, Chris A.

 

 

 

Would it  be ok to send you a pm, I have a couple questions for you. Thanks.

 

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On 5/13/2020 at 8:42 AM, Jesal said:

Thanks for the spreadsheet. I can live with 26x40". That's not much bigger than what I have now. I will play around with it more.... Thank you Chris

Just remember that the title of this thread is "A K-402-Based Full-Range Multiple Entry Horn", meaning that if you try to skimp on the mouth size of the horn, you also give up directivity of the resulting loudspeaker at midrange frequencies.  I believe that a major reason why the Danley Synergies sound so good is due to point-source controlled directivity in the 200-1000 Hz band.  Most or all folks on other forums fail to recognize this.

 

Chris

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18 hours ago, Chris A said:
Just remember that the title of this thread is "A K-402-Based Full-Range Multiple Entry Horn", meaning that if you try to skimp on the mouth size of the horn, you also give up directivity of the resulting loudspeaker at midrange frequencies.  I believe that a major reason why the Danley Synergies sound so good is due to point-source controlled directivity in the 200-1000 Hz band.  Most or all folks on other forums fail to recognize this.
 
Chris

Understood. I'm a bit challenged horizontally with the screen. I can maintain the K-402 dimensions but will have to turn it sideways. Just trying to decide which is more important and have more advantages, smaller 90 degree horizontal horn or keeping a bigger mouth size but with 60 Horizontal coverage?

Sent from my SM-G955W using Tapatalk
 

Edited by Jesal
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32 minutes ago, rickmcinnis said:

I do not see, though they have yet to be delivered - how one can use fasteners at all from your description

New Center profile 500px.jpg

 

1676789273_Boxfront-empty300pix.png.529fbb5403517de425f36f8149f43407.png

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Understood. I'm a bit challenged horizontally with the screen. I can maintain the K-402 dimensions but will have to turn it sideways. Just trying to decide which is more important and have more advantages, smaller 90 degree horizontal horn or keeping a bigger mouth size but with 60 Horizontal coverage?

 

Sent from my SM-G955W using Tapatalk

 

Mine are being setup to where they are vertical due to the floor space they would take up. If you go this way either make your cabinet taller, or make some stands to get them at the proper height. Mine are 4' tall, and pretty close to my ear height for the driver....could go maybe a few more I chest but then I would have to raise my FP.

 

Sent from my SM-T830 using Tapatalk

 

 

 

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20 hours ago, Chris A said:

New Center profile 500px.jpg

 

1676789273_Boxfront-empty300pix.png.529fbb5403517de425f36f8149f43407.png


Sorry Chris what are you showing with these pictures?  I also was wondering how to deal with fasteners through the thin walls of the horn.  I’m currently leaning towards Ron’s method of gluing stiffening boards to the other 2 surfaces then screwing the woofer mounting boards to those.  This is appealing as a potentially much stiffer surrounding “box” arrangement and doesn’t require fasteners/cutting the horn except of course for the ports.  Thoughts?

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1 hour ago, Delicious2 said:

Sorry Chris what are you showing with these pictures?

How the mouth of the horn is fastened/clamped to the box. 

 

Here is the way that Danley Sound Labs attaches to the interior horn walls--through bolts with countersunk heads...and T-nuts to the long stiffening bolts/rods that attach to the outside box perimeter:

 

31b50c51_vbattach209352.jpeg

 

Chris

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36 minutes ago, rickmcinnis said:

I am assuming that Chris A's K402s are made from a thicker material.

Yes, they are.  The horns that you have probably weigh 15 pounds.  My K-402-MEH prototype horn weighs 25 pounds.  The K-402s apparently used to be made via compression molding, but were re-sourced from another supplier as an apparent injection molded horn about 3-to-4 years ago, and the overall weight dropped when that occurred.

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what is that countersunk screw holding onto?  Yes, the older horns are heavier/thicker, I have both but wouldn't feel good about countersinking screws in either case - too thin/brittle.

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2 hours ago, rickmcinnis said:

As far as I know DANLEY is using (at least) 0.5 inch plywood for the horn walls so his using countersunk fasteners is not exactly analogous to the plastic horn.

How so?  The horn material in the third generation horns that you've apparently received recently (and I don't call them "plastic", but rather ABS--because the word "plastic" connotes negatively with most people) is not as tough as the second generation compression molded horns--the ones that weigh 25 pounds, but iin my experience, it's still thick/tough enough to anchor t-nuts and countersunk head bolts-like Danley does in its Synergy series.  I used self-tapping screws in the second generation horn for attaching the woofer mounting pads--made of 3/4" MDF, but I could have also made it with countersunk bolts. The key is expanding the contact area of the head or nut to grab enough material to make the connection.

 

You could also use epoxy to bond to the horn material on the reverse side of the horn (epoxy is really the reference standard for bonding to dissimilar materials), but remember that epoxy is NOT polyester resin--so don't try to use polyester resin to bond to the horn--it probably won't form a strong bond like epoxy will. 

 

Chris

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On 5/27/2020 at 2:26 PM, Chris A said:

The key is expanding the contact area of the head or nut to grab enough material to make the connection.

 

I use this type of cabinet bolt for attaching the K-402 flange to the mounting brackets. The low profile, wide head design might work good for other applications too.

 

IMG_6879.JPG.a4bb05762697df596e235089ef7fe581.JPG

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23 hours ago, rickmcinnis said:

surprise by how tight the fit is around the horn mouth for the fasteners of the CD. Had never dealt with studs before.

 

In my experience, compression driver mounting studs are common. The K-402 throat does create a tight tolerance, so it is helpful to remove (or install) all four nuts using an even pattern, not just completely removing (or installing) one fastener at a time. After doing it a couple times and learning the technique, it becomes fairly easy.

 

IMG_6894.JPG.e190a011cb1ad4f0bcce8ed4b02600c2.JPG

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