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Old 2nd December 2012, 11:42 AM   #251
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Most certainly am interested. My focus at the monent is good quality portable sound. So cornu wont fit in pairs under my laptop. Lol.

Nah i have a nice pair of two way four inch car speakers id like to try. Theyre Alpine TypeE car speakers. Not sure where id use em tho....
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Old 2nd December 2012, 12:19 PM   #252
xrk971 is online now xrk971  United States
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Originally Posted by Cal Weldon View Post
I'm not sure the extra stiffness is necessary when you look at the walls. Except for where the horn exits, is there any difference in SPL on either side of any channel? Why does it need to do any more than it is?
I agree that internal walls shall remain foam core as it is stiff enough and may even provide some acoustic damping of higher frequencies, but major selling point is that it makes the build of the curved spirals pretty easy - pretty much the crux of the problem why more folks haven't tried the Cornu spiral before. I was just thinking of the door skins for nice looking facing kind of like veneer to apply to the foam core covers. I am still sticking with foam core for the major structure to the extent possible as I don't have a workshop or power tools other than drill and jigsaw.
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Old 2nd December 2012, 12:24 PM   #253
xrk971 is online now xrk971  United States
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Originally Posted by klampykixx View Post
Most certainly am interested. My focus at the monent is good quality portable sound. So cornu wont fit in pairs under my laptop. Lol.

Nah i have a nice pair of two way four inch car speakers id like to try. Theyre Alpine TypeE car speakers. Not sure where id use em tho....
For portable stereo sound, try the simple one fold wall hanging transmission line mentioned earlier in this thread but scale it down. It sounds very good with super bass extension and a nice even round feeling that everything is all there. To make more compact, maybe fold it three times but keep it fairly flat circa 2.5 to 3 inches. Check out Cal's sig line in his projects he has several portable speaker systems. My fav is the Pentagon tower with 5 sides each with what looks like 3 in drivers and a tweeter with the amp inside the tower. Not sure how he manages stereo with 5 sides???
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Old 2nd December 2012, 12:40 PM   #254
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I am starting on the Son of Cornu (14 in square desktop horn for 2 in pc speakers). I just laid out design on foam core. I am making all walls curved to extract as much sound from these tiny drivers. The channel depth will be 2.0 inches.
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Old 2nd December 2012, 01:03 PM   #255
xrk971 is online now xrk971  United States
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Originally Posted by Cal Weldon View Post
You are owed them and even even more. You helped me scratch a long standing itch.

To possibly include a silkscreen cover over the drivers.

WHAT? I CAN'T HEAR YOU, I HAVE TO GO TURN THE BASS DOWN.

There, does that simplify it?
Cal,

You are welcome - It does look like you have had a thing for these spirals for some time now and am glad you were finally able to scratch that itch. You have even spoken to Daniel, the original designer/builder? It was worth the wait but I'll bet you are wishing you did this earlier as it sounds so good.

I am interested in more of your observations/critique of the sound once you get to mount it in a better location and have more time to listen. I don't think it is ever a problem to have too much bass with a horn as this allows easy fix with stuffing and one can adjust it down to suit and skip the whole BSC network. It's nice to have direct connection from amp to driver with nothing to add funny business along the way.

Do you have any recommendations for a good 2 inch full range driver? I am trying this next to make the desktop Son of Cornu. It's really an experiment to see what the limits of the size/scaling is. I am not expecting it to work well but I may be pleasantly surprised. The earlier poster may go the other way and make the 8 inch monster Mother of Cornu with the Visaton B200.

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Xrk971

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Old 2nd December 2012, 02:19 PM   #256
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Do you have any recommendations for a good 2 inch full range driver?
Visaton 2231 FRS5 2" full-range from Parts Express
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Old 2nd December 2012, 02:38 PM   #257
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Visaton 2231 FRS5 2" full-range from Parts Express
This looks just like the speaker I pulled from the Logitech S 120's. It just has one less small hole on the mounting tab but otherwise looks the same with paper cone and foam surround. A bonus is it is 4 ohms, the back is labeled just 5 Watts, 4 Ohms. The cost of a pair of S 120's is lest than one of these drivers from PE. Plus you get a 3 Watt amp with 3.5 mm jack and PS.

I was thinking of a fancier Tang Band or something like that with a lower Fs. Any recommendations there?
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Old 2nd December 2012, 02:55 PM   #258
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Originally Posted by xrk971 View Post

I was thinking of a fancier Tang Band or something like that with a lower Fs. Any recommendations there?
If I were to try one it would be the Tang Band W2-803SM
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Old 2nd December 2012, 03:04 PM   #259
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Originally Posted by xrk971 View Post
Wow, they would be beeeeggggg! Simple math/scaling says that the original design is for a 4 inch driver, the Visaton B200 being 8 inch, everything doubles. So the dimensions of the box are 150 cm square and about 10 in thick. You would need a double sided Cornu for 8 horns per driver. The sound with 96 dB of sensitivity would just be mind boggling if you think how big the mouth area is. The effective piston area of this driver is 214 cm square cm, the expansion ratio is about 24x this means the total mouth area is about 800 square inches! Oh, and I forgot to mention that bass freq would reach sub-audible to about 18 Hz. This would be something to see and feel.
Argh! Could be a problem to "hide" the monsters in the living room. I don't mean to bug you guys with noob questions. Can you point me to a simulator or formulas that would help me test ideas? For instance, given that I wouldn't care for such low(18Hz) bass, what if I use the B200 with smaller/shorter spirals?

BTW, found an easy way to draw perfect spirals of any size.
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Old 2nd December 2012, 03:09 PM   #260
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Originally Posted by ikoflexer View Post
Argh! Could be a problem to "hide" the monsters in the living room. I don't mean to bug you guys with noob questions. Can you point me to a simulator or formulas that would help me test ideas? For instance, given that I wouldn't care for such low(18Hz) bass, what if I use the B200 with smaller/shorter spirals?

BTW, found an easy way to draw perfect spirals of any size.
To calculate the lowest fundamental 1/4 wave freq, divide speed of sound (about 342 m/s) by 4 x the path length of the longest channel in meters. For example, for a 1.5 m path, 342/6=57Hz. Use current design but modify by putting bigger central box for speaker chamber, this will only add 4 in to your overall dimensions, but the depth still has to be like 9 or 10 inches to let the driver have enough room to breathe.

Last edited by xrk971; 2nd December 2012 at 03:12 PM.
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