I would recommend a 24" for the Dynavox. I do believe you will note a significant difference.
That was my first go at it, in a 27". I found it shy on the top end. The cabinet offers a lot of bass for most persons ears.
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I missed this altogether. What I am glad about is that it shows only slight differences on either side of the horns walls and why foam core works so well. Now, we can't do anything about the chamber unless we want to double the wall thickness but those are small pieces to begin with.
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Now weknow for sure you're retired. Or was it too much coffee?
I am grasshopper. Masters are many here. I was intrigued for many moons before X came along with his idea of how to make this work.
I call him my Altitude.
I elect Arthur to be the first builder.
I tried once. I got about 1/4 the way into it before I had to buy my wife a new heat gun, I mean hair dryer.
Don't blame me, this started decades ago but I never thought about the reality until our good friend XRK came up with the idea. I just jumped on the wagon and yelled GIDDYUP!
The addiction only costs a small amount, you don't end up in hospital, and you have something to show your friends in the end.
Please don't go larger than a 3" driver in a 24". Build a few and you'll understand why,
Dollarama or equivalent. Go to an arts and craft store and pay WAY more.
No. These speakers are made for ***** and giggles. Your friends will be looking for the bass unit for quite some time before they finally believe that what they are hearing is coming from only these boxes. These are not designed for critical listening.
Mind you, no small driver ever really was unless you live in a small box yourself.
Shhhh! We all know he's looking for us. Daniel Ciesinger that is. Keep a low profile and we should be fine.
Yes that was one of the sites for sure. There was no way in heck I was going to be building anything like that when I was living in a tent.
Here is another.
https://6moons.com/audioreviews/cornu/cornu.html
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Yes Moray, reprographics shop. Take the small version, tell them what the total size is, take it home in one, two or four pieces, tape in place and start poking holes every 1 cm through your template paper into your baffle. Then use a pencil the connect the dots on the baffle and start your assembly. You'll note that in each case I take that anomaly of the secondary horn separation out of the equation. It may be moot but I couldn't live with myself if I didn't. 😉
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If its Fs is around 80Hz?, you might not have to worry about anything larger than 24".
Please do. As I have said many times, they are the most rewarding projects I have done. The build and the results continue to warm the heart to this day.
My fave by far was the 36" with a 40-1354 Radio Shack 5.25" driver from 40 or more years ago. Thanks in a big part to planet10's artwork on the old girls, they have impressed more persons that I care to mention.
Arthur, If you want to cut down on the work involved, go back and review the construction tips I gave along the way. Heaven forbid, if I ever decide I need another of these, I can do it in 1/4 of the time the first one took.
I have 20, 24, 27, 36 and 48 inch versions along with other similar experiments so I don't see it in my future, but I sure as heck love when others do.
My fave by far was the 36" with a 40-1354 Radio Shack 5.25" driver from 40 or more years ago. Thanks in a big part to planet10's artwork on the old girls, they have impressed more persons that I care to mention.
Arthur, If you want to cut down on the work involved, go back and review the construction tips I gave along the way. Heaven forbid, if I ever decide I need another of these, I can do it in 1/4 of the time the first one took.
I have 20, 24, 27, 36 and 48 inch versions along with other similar experiments so I don't see it in my future, but I sure as heck love when others do.
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I concur with Cal that this was one of the most fun speakers to make. It really does have some amazing big sound.
Hey Cal well the XT-Mini driver in its 3.4 litre cabinet response is down 6db at 68 Hz.,the woofer VC is1.25" which eats up a bunch of that cone area (3.25" dia.) and it's 88db efficient. Seems to me at a guess the Fs is lower than 80Hz. maybe 70 is Hz.? I can't find any specific data on the driver itself. If you suspected that it needed to be larger than a 24 " design what would be your guess on a next larger size would be?
Perhaps it might be a good idea if I start with a small Cornucopya first to learn the build technique? I have a pair of SB Acoustics FR 2.5' drivers Qts0.68 f/s of 115Hz. once I learn on a smaller cornucopya I can later build larger ones. Does that sound reasonable or is if physically easier to learn/work on a larger cabinet first? Thanks for the direction and help.
Cal sorry I don't understand what this means? could you explain please? thank you.
In post 2949 you'll note I have recurved the spiral in the two locations where it breaks off into four.
that is what I was wondering but did not recognize the terminology. It is the point where you start the new pair of shorter length horns. Took me a while of wondering why there was a difference in the expansion or flair rate of the two side horn sections wondering why they were different diametres. Am I to assume tat the sketched in line depicting the more gradual expansion is the desired one? So the flair rate of the two horn sections beginning at this point is this intentional by design or simply a byproduct of the method used to include two more horn sections? Thanks for explaining and for pointing this out
Moray, if that works for you, fine. For me it was:
"That doesn't look right" 🙂
"That doesn't look right" 🙂
Cal the paper lament of the core foam can be stiffened but I am not sure just how much difference it would make. Make a solution of pva white glue reduced fifty percent with water plus twenty five percent plaster of paris powder by volume. Coat the board surfaces, brush on a light coating (3 -4 coats) and let each coat dry well. The board will be stiffer now but will it make a significant difference, I could not say.This process will however insure that the spirals are well sealed and have no air leaks.