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Old 24th November 2012, 03:17 AM   #671
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Quote:
Originally Posted by JRKO View Post
Does axial length mean the distance between centres, from throat to mouth? Is it throat area that I then need then to calculate the flare?
Correct. I found my old expo spreadsheet, so post the mouth, throat, axial length of the various horns or input them into HR or similar.

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Old 24th November 2012, 03:27 AM   #672
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Originally Posted by Kindhornman View Post
There are many other ways that the shape change can happen and inner and outer cells can be different in cross-sectional change while the overall expansion rate of combined cell area is identical for the final cutoff frequency.
Absolutely! Back in the '60s I designed slot car parts for awhile and we had this huge, old plastic molding machine, but for all its size it couldn't make parts much bigger than a motor end bell, but I had audio wet dreams about a house size one that could mold massive multi-cells made from Delrin with 64 or more cells starting with ~0.2" diameter throats.

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Old 24th November 2012, 03:53 AM   #673
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GM,
What is your idea behind so many cells? How wide a dispersion pattern are you trying to produce?

Slot cars now that is going back. I had some myself and went to my local track to run the cars. I'm curious why you would think to use Delron for a horn lens, wouldn't be my first choice for a material. And attaching the multiple cells together would be a real bear. It isn't a very stiff material but is high density for a plastic.
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Old 24th November 2012, 09:01 AM   #674
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Quote:
Originally Posted by GM View Post
... so post the mouth, throat, axial length of the various horns ...
1005:
  • Axial length =15.5"
  • Mouth = 6.25" wide, 4 sides
  • Throat = unknown, but between 0.75" and 1"
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Old 24th November 2012, 10:31 AM   #675
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Thanks for the additional info fellas.

Can anyone point me to a user guide for Hornresp?
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Old 24th November 2012, 12:15 PM   #676
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The best hornresp guide is hornresp's built-in help file, IMO
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Old 24th November 2012, 12:24 PM   #677
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Quote:
Originally Posted by derwhalfisch View Post
The best hornresp guide is hornresp's built-in help file, IMO
D'oh
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Old 24th November 2012, 03:31 PM   #678
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Quote:
Originally Posted by Pano View Post
1005:
  • Axial length =15.5"
  • Mouth = 6.25" wide, 4 sides
  • Throat = unknown, but between 0.75" and 1"
x = axial length distance from throat where area doubles.

0.75" square throat:

length 15.496
multiplier 6.117
length (x) 2.533
k 0.274
Am 39.063
At 0.563
Fc 295.00
SoS 13,548.00


1" square throat:

length 15.498
multiplier 5.288
length (x) 2.931
k 0.237
Am 39.063
At 1.000
Fc 255.00
SoS 13,548.00

I just found out that converting/inputting the areas and length into HR displays Fc in the F12 window [though insignificantly different due to conversion, different SoS than the one Altec listed] and allows one to choose axial length 'x' when exporting the design data, saving one from oddball fractions, so seems the easiest way overall to get all the layout particulars.

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Old 24th November 2012, 05:04 PM   #679
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Quote:
Originally Posted by Kindhornman View Post
What is your idea behind so many cells?

How wide a dispersion pattern are you trying to produce?

I'm curious why you would think to use Delron for a horn lens, wouldn't be my first choice for a material.

And attaching the multiple cells together would be a real bear.
Hopefully improving a multi-cell’s overall performance and particularly its HF response over existing designs.

??? Wasn't trying for any particular polar response per se, just that starting with a smaller throat yields a smaller mouth for a given axial length, so it takes more cells to get ~ the same polar response, throat, mouth area as an 1803/whatever.

Again, it was just a 'pipe' dream of a ~20 yr old whose manufacturing, materials knowledge was pretty much limited to what he had learned to that point from hot rodding motorcycles, cars along with a several year stint working in an intense design engineering environment that covered architectural, structural, mechanical and topography, which taught him enough to help design all aspects of slot car parts/assembly; so naturally he would have fantasized a horn molded as a single piece [not individual parts] using a material he had some ‘hands on’ knowledge of.

Delrin had already been proven a suitable material for injection molding of motor end bells and spur gears due to its damping ability over a wide HF BW while maintaining sufficient rigidity, heat resistance at a low weight and didn’t audibly ‘ring’ in my rather crude testing, so seemed a good enough material.

I guess I could have gone 'over the top' by fantasizing using Bakelite, though being just a ‘pipe' dream, I didn't waste my time giving any real thought to any design details as it seemed much too far-fetched/expensive a venture in my rather creatively challenged mind to ever become a reality.

Since this is apparently more your area of expertise, what material would you have specified circa 1967 [and today] for a one piece molding of a multi-cell to cover the 300-20+ kHz BW?

GM
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Old 24th November 2012, 07:02 PM   #680
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Why oh why am I so freaking stoopid?!

GM I thank you in blind faith for the post below on the two throat variations. Unfortunatly I'm an idiot and despite looking thru the HR help section I dont get most of the info you've posted.

I'll have a glass of wine and then try using HR itself to see if I can make it squawk

James
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