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Old 2nd December 2012, 01:40 AM   #221
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Quote:
Originally Posted by Cal Weldon View Post
Before I start I want to say that klampy's unit sure looks trick. I hope it sounds that much better when you seal it up.
thanks mate means alot

heres a shot from inside the mouth. its getting covered in a black velvet material, and running blue thin pile carpet on the inside, leaving the walls red.

Click the image to open in full size.
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Old 2nd December 2012, 01:48 AM   #222
xrk971 is offline xrk971  United States
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Planet10,
Your assumption is that all flow paths or air columns are combined and modeled as one, when in fact it is the channel walls separating them that makes them independent. Even with symmetry, there are still two separate horns as the lengths are unequal. I am not sure how to model two separate exit terminii at different lengths in the model. In fact, I am not sure what happens when you take a trumpet and add two bells to it at different lengths. I think the waves will establish in one or the other rather than split they may oscillate back and forth but this is the nature of fluid dynamics. In this sense I think the solution is to superimpose the two different length solutions. If you use MJK's models, the location of the terminus for each case is different (two vertical, and two horizontal) and this affects the final SPL calculation in the simulated room.
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Old 2nd December 2012, 01:51 AM   #223
xrk971 is offline xrk971  United States
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Originally Posted by klampykixx View Post
thanks mate means alot

heres a shot from inside the mouth. its getting covered in a black velvet material, and running blue thin pile carpet on the inside, leaving the walls red.

Click the image to open in full size.
Looks very cool. How does it sound?
Double you get any stereo imaging?
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Old 2nd December 2012, 02:07 AM   #224
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thanks XRK, as far as "stereo imaging" no.. its a single sound source, but i do get the left/right sounds, and i also do plan to fit a reflector infront of the outermost drivers to try and aim some of the higher frequencies out of the mouth better.

the closer i get to having a sealed box, the better it is sounding, and also the more i listen to it, the better its sounding to me. ive been playing with the Dolby software on my laptop with it, and i can crank up the 30-100hz sliders on the EQ and it does sound much much better, but ultimately i lose volume when i do so for running out of excursion on the drivers.

back to the shunting of the drivers, i was considering mounting a tweeter on each of the front faces of the box, and then lowpassing the rear/innermost drivers to act more like subwoofers.

i tried just holding the cones of the front most drivers still to assess if less drivers made better or worse, and volume dropped considerably when i cut two out of the equation. so definately winning with the Quad setup.

how much bass/rumble to you guys get from your spiral horns?
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Old 2nd December 2012, 02:07 AM   #225
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Originally Posted by xrk971 View Post
Planet10,
Your assumption is that all flow paths or air columns are combined and modeled as one, when in fact it is the channel walls separating them that makes them independent.
It is the same technique Martin used to model Sachiko.

Quote:
two bells to it at different lengths
The horn is square, the path lengths should be the same.

dave
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Old 2nd December 2012, 02:11 AM   #226
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heres the little amp thats going into it

Click the image to open in full size.

being class D, i presume that if i run it at 4ohm, its probably not going to like it, but at this sort of power i doubt its going to be an issue... lol
would i be correct to assume its rated to 8hm and that running it at 4 will approximately double the output power to roughly 6w?
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Old 2nd December 2012, 03:04 AM   #227
6L6 is offline 6L6  United States
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A quick question on the Cornu spiral - Is there any reason why the spiral pattern can't be taken larger? I.E., make the baffle 3'x3'? (Or bigger?)

I will be buying a bunch of foam core monday, and proceeding with this fantastic project. SHMBO actually likes the idea!

One, well, kinda small thing... I don't have a suitable driver. Any suggestions? FE126En? A Markaudio?
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Old 2nd December 2012, 03:16 AM   #228
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The horn is square, the path lengths should be the same.
I take that back.

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Old 2nd December 2012, 04:04 AM   #229
xrk971 is offline xrk971  United States
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Originally Posted by 6L6 View Post
A quick question on the Cornu spiral - Is there any reason why the spiral pattern can't be taken larger? I.E., make the baffle 3'x3'? (Or bigger?)

I will be buying a bunch of foam core monday, and proceeding with this fantastic project. SHMBO actually likes the idea!

One, well, kinda small thing... I don't have a suitable driver. Any suggestions? FE126En? A Markaudio?
3 ft square will give you a bigger mouth and expansion ratio, so the volume would go up and you may get way too much bass. Cal is already noticing that the bass is larger than mids, also path would be longer and tuning frequency will go below what the driver can handle - unless you model it, hard to tell. The 70 cm size already goes down to 38 Hz based on the 2.24 m path of the longer horn. I think the driver selection does not seem to be critical. The original Cornu uses several different types of drivers (Monacor, Lowther DX, Fostex) with the Fostex FE108ez being the main. Personally , I would pick one with more xmax. The one Cal is using seems to work well too. I am using a much smaller 3.5 inch high Qts driver and it works fine. Just size the throat area to match the driver piston area Sd. I personally, would pick the MA CHR70 for my next one given the combination of performance and price. One thing that I noticed with the Cornu is that it is a very efficient and loud speaker that works very well even at lower volumes. The richness and depth of the bass is still there even at low volumes. This means that even lower efficiency drivers will sound loud, and high efficiency drivers will be even louder. If you matched this up with a 98 dB driver and a SET or a Pass Labs d'lite, it would be really special.

Last edited by xrk971; 2nd December 2012 at 04:10 AM.
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Old 2nd December 2012, 04:06 AM   #230
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A scalable trace of the spiral

dave
Attached Files
File Type: pdf Cornu-clone-spiral.pdf (13.0 KB, 1196 views)
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