Ever think of building a Cornu Spiral horn? Now you can!

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Actually, I suspect that Cal and I are old enough to have seen this idea on the nipple of a mucilage bottle in elementary school(or is it sedimentary school-"Settle down, you!").

It's more impressive that we have some memories of such, than that a handy person comes up with it new.
 
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Ahh those memories of mucilage suddenly came back. Rubber flat tipped nipple in the bottle. I never know mucilage is basically plant or animal derived mucous like substance that is edible. Used for postage stamp glue and envelope glue. Hence the requirement that it’s edible. I do not remember a metal two prong tip so Cal still gets credit for this invention. :)
 
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I remember a slanted rubber tip with a flat notch, thus two squarish points. I think it helped pull the last drop back in. So the patent would have to be for the use of rather than the shape alone. Would still be valid, though, lacking prior use.

Some comedian had a bit about two five-year-olds standing and peeing in the shallow end of the pool "do you eat the paste?" "It's a given". We had a teacher who showed us how to make paste, play-doh, and silly putty.
 
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OK, so back to speakers for a minute.

One done, the other has to wait for a couple days.

Cornu's biggest asset is to take an otherwise good FR and give it bass beyond it's regular means. Doing a Cornu with a woofer and it's own plate amp means there is much better control over things, but unfortunately, the ****s and giggles are all but gone. The drivers have sat in storage for a couple years and need time to stretch their legs. What I can say at this point is there is a room full of bass in the bedroom with no discernible cone movement. I will have more to say later.

The second pic is an option for where they (or maybe just one) can go if it goes well.
 

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Ahh those memories of mucilage suddenly came back. Rubber flat tipped nipple in the bottle. I never know mucilage is basically plant or animal derived mucous like substance that is edible. Used for postage stamp glue and envelope glue. Hence the requirement that it’s edible. I do not remember a metal two prong tip so Cal still gets credit for this invention. :)

this is the one I remember from school (50+ yrs ago :eek:)
mucilageplastic.jpg
 
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These have been scaled as small as 14in (35.6cm) for a 2in driver. They still sound nice with lots of sound amplifcation of the back wave. However, the deepest bass notes scale accordingly. Standard dimension is 74cm and that is good for about 50Hz. So 74/60x50= about 62Hz. Make sure driver magnet still fits in scaled down rear chamber. Depth scales with Vas and really needs sim with particular driver T/S parameters. However, about 8cm to 12cm should be fine.
 
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Hmm, baffle area grows quadratically with edge length. Any arbitrary path on a 2 dimensional sheet will scale linearly with the extent of the sheet dimensions. Take for example the circumference of a circle. It scales with diameter as pi x D. You could have say, 10 concentric circles representing the total path of the horn. The total length of all the nested circles will scale linearly with the diameter (or edge length of the baffle).

It's been a while since I looked at the Cornu pathlength but I seem to recall that for the 78cm one, the longest path is 2.2m. The low frequency is not exactly predicted by th length as there is substantial flare of the mouth so effective length is a bit shorter, hence the 50Hz to 60Hz low end as I recall.
 
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I wasn't coming back till I sorted this out. No matter what I did, there was just no love for these 48"ers. That TB driver is great and has served me well for years but just isn't meant for the Cornus. Trust me I tried but no go. So as I sat drowning in my speaker tears I had a revelation. You see those Airborne drivers either side of the TV?
 

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With my fingers crossed, I mounted them in the Cornus, moved the boxes to the diningroom, grabbed a different amp and fired them up.

WTF? They sounded like crap. No highs, no lows, just a dull ceiling speaker sound. The phone rang so I turned the volume down quickly. Emphasis on the word quickly. I heard a scratching sound.

You know where this is going don't you?

Got out the anti-static spray, did the volume pot and fired it up again.

Wowza!

Once again, the magic has returned. I mean in a big way. This 48" size allows for the bass hump to be low enough that it is reinforcement not a bloated distraction. I am able to get a bit of chest thump. Something I've not experienced with a 6.5" driver.

Gotta go, music's playing. :D
 

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Nice ending there, Cal. :)

The TB’s are subwoofer drivers. I thought you were making a subwoofer - so doesn’t surprise me that they sound bad as a full range?

Those Airbornes are the wooden membrane right? Nice drivers - and seems like a match made in heaven for the fine Cornu’s.

Well done, and a good save there. But what will you do with those nice (Chrisb made?) Aironkens?