DR250 Three and Four

[Tom Smit]

Nice job!

[LelandCrooks]

Nice. Well done.

[Dave Non-Zero]

That is a great way of keeping the box square! I'm going this route with my next pair! Thank you!

[Harley]

Nice build method Lastcat.

What material did you use for the curved butts? It looks like ply to me.

Were they straight cuts at the top and bottom, using the height of the half circles to allow for the gap toward the front because of the opening rake angle, or did you shape the top and bottom? I am also curious to know how you fitted these in because of the wedge shape of the box looking side on.

[Lastcat]

Nice build method Lastcat.

What material did you use for the curved butts? It looks like ply to me.

Were they straight cuts at the top and bottom, using the height of the half circles to allow for the gap toward the front because of the opening rake angle, or did you shape the top and bottom? I am also curious to know how you fitted these in because of the wedge shape of the box looking side on.

Thanks Harley. Its 1/8" Bendable Plywood. Yes, its a different shape. I made 4 DR200's using Sheet Metal, and this time went with Bendable Ply. Its a matter of cutting to fit. The sides are straight, but the top and bottom have a very large Radius, to be able to fit. Just trial and error. Once I get one to fit, then I can just copy that pattern to the other butt cheeks.

After trying both, I like working with the Sheet Metal over Bendable Ply. Here's an example of what I meant, this is an exaggerated drawing.

[Harley]

After trying both, I like working with the Sheet Metal over Bendable Ply. Here's an example of what I meant, this is an exaggerated drawing.

Thought so - thanks for confirming.

[UROK]

Really neat. Interesting method. Proper pro results. The piezo arrays are SO pretty!

How about where the sides and rear curved back edges meet? Does that need to be sealed or fixed? If so how did you do it, please?

Thanks for sharing!

Truly inspirational (even if I will always fall short of this standard )

[Lastcat]

Really neat. Interesting method. Proper pro results. The piezo arrays are SO pretty!

How about where the sides and rear curved back edges meet? Does that need to be sealed or fixed? If so how did you do it, please?

Thanks for sharing!

Truly inspirational (even if I will always fall short of this standard )

Thanks Urok, for sure seal the Butt Cheeks to the Sides, just PL. Just leave enough of the edge to overlap, about 1/8", to contact with the sides.

[UROK]

Thanks, man!

You make it look so easy! Sign of mastery.

[Dave Non-Zero]

Nice build method Lastcat.

I am also curious to know how you fitted these in because of the wedge shape of the box looking side on.

im still interested in how easy it was to get the inner edge (throat) of the but curves in to glue.

did you cut the panel curves to be be a close fit? or was there wiggle room for getting past the narrower back bit?

am i over thinking it?



it looks a very close fit, but i suppose there is a half inch either end that i the safety factor?

[Lastcat]

Dave, its just a matter of trial and error. Not as hard as one would think. You could always start with a piece of cardboard, and trail fit, then cut your Bendable Ply. Once you get a pattern, then you can copy that to your next butt cheek.

It takes a bit of bending and twisting to get the cheeks to fit, I had about an 1/8" wiggle room around the top and bottom. The center that fits against the Horn, just have it glued to each butt cheek.

Once you make the pieces, you will see what needs glued and attached. I used a Brad Nailer, and I also glued both cheeks in, at the same time. The only problem I had, was the center would try and slide out, so get that nailed down first, then work the cheeks down, and nailed. Hope this helps.

[Dave Non-Zero]

Cool. I suppose it's one of those things that is easier in practise than it is to look at. I've just got a compressor so I'll be buying a brad nailer soon. It'll definately be easier than trying to hold the bend while screwing them down.
I hope you believe that imitation Is the most sincere form of flattery.

[Lastcat]

I hope you believe that imitation Is the most sincere form of flattery.

Thanks Dave, you have built a few 280's, so this should be a simple build for ya, you might even figure a faster and simpler way, as far was we know. Post pics if you can.

[Dave Non-Zero]

Hahah fast and simpler!!! Do you realise how long it is taking me to get round to building my next pair??? I've had the horn throats done for over a year.
I'm at a good stage to use your build the box first idea tho, and this is inspiring me to really knuckle down and make some progress before the real bad weather hits.

[Dave Non-Zero]

Increased array height means greater line array effect and therefore better distance coverage and lower absolute volume required.