BillFitzmaurice.info

Keryn O'Shea wrote: ↑Fri Nov 03, 2023 4:38 amHas anyone else wondered before if the OTop8 cab could be built with a trapezoidal side profile for splaying like the DRs

I have not contemplated the idea. But I don't see why not. As long as the internal volume is kept the same it should be no problem.

If one were to keep the volume exactly equal, the first idea would be to make the rear end a bit shorter. Which in turn would require the front to be a bit longer. However that would mess up just about all dimensions. Probably more trouble than it is worth.

So thinking this through, my second guess is to keep the front as designed, just make the rear end shorter. Then compensate for the smaller volume by making the cabs a tad deeper. With some math one could work out how much deeper the splayed cabs need to be to compensate for lost volume. Alternatively some 3D software would be able to help out with that.

Perhaps I am overthinking this and just making the rear a bit shorter without further compensation might work out well enough. Up to Bill to indicate the margins of internal volume wrt performance.

And one final thought: the splayed external format would make the wood working more complex than the original design. One of the major design objectives for the OT's (as I understood) was to keep them as simple as possible. Easy to build, with a minimum of tools and craftsmanship. If you go through the trouble of making your OT8s into splayed cabs, why not go for DR200s instead? Their efficiency makes them stupid loud, for both their size and required amp performance. Having owned a DR250 I can say that I have never heard a sweeter sounding PA top.

The plans don't include that option because unless you have at least three of them stacked it there's no reason for it, and if you need three OTop 8s stacked it's the wrong cab, you should be building either OTop 12 JArray or one of the DR series.

BTW, the sides of the DRs aren't trapezoidal, the top and bottom are. DRs are never splayed, which is to say placed side by side. They're always vertically stacked. All speakers should be.

AntonZ wrote: ↑Fri Nov 03, 2023 6:09 am I have not contemplated the idea. But I don't see why not...

I appreciate your contemplation mate

AntonZ wrote: ↑Fri Nov 03, 2023 6:09 am ..And one final thought: the splayed external format would make the wood working more complex than the original design. One of the major design objectives for the OT's (as I understood) was to keep them as simple as possible. Easy to build, with a minimum of tools and craftsmanship. If you go through the trouble of making your OT8s into splayed cabs, why not go for DR200s instead? Their efficiency makes them stupid loud, for both their size and required amp performance. Having owned a DR250 I can say that I have never heard a sweeter sounding PA top.

Yes I agree AntonZ, and..

Bill Fitzmaurice wrote: ↑Fri Nov 03, 2023 7:20 am ...unless you have at least three of them stacked it there's no reason for it..

Absolutely Bill, I ask as I built a set of TLA Pros which (I love but) I'm looking to break down into more manageable cabs, and building 16 DR200s would take me into my next life I think!

Bill Fitzmaurice wrote: ↑Fri Nov 03, 2023 7:20 am BTW, the sides of the DRs aren't trapezoidal, the top and bottom are..

Bill I don't want to appear to be arguing with you, however I'm confused, below are shots of the sides and bottom of a DR

Bill Fitzmaurice wrote: ↑Fri Nov 03, 2023 7:20 am DRs are never splayed, which is to say placed side by side. They're always vertically stacked. All speakers should be.

Right yes, I should've said vertically stacked, thank you

Sorry if I've highjacked your thread Kranku!

The DR side panels are trapezoidal, but the result is a trapezoidal cab for vertical J array stacking. With commercial trapezoid cabs the shape is there to place them side by side, aimed outward with respect to each other, known as splaying. The intent is wider dispersion, the result is narrower dispersion in the mids, and comb filtering in the highs. Why do they make them? Because that's what buyers, who have no idea how sound waves work, want. It's the very rare manufacturer willing to lose sales by not giving customers what they want, even if it doesn't work.

Ah ok, I get what you meant now

Bill Fitzmaurice wrote: ↑Fri Nov 03, 2023 5:14 pm It's the very rare manufacturer willing to lose sales by not giving customers what they want, even if it doesn't work.

Like a solar powered torch?

That's perfectly practical, given the efficiency of LED bulbs, assuming you can leave it out in the sun all day to charge. I've seen quite a few that are very well reviewed. But you have to know their limitations.

Bill Fitzmaurice wrote: ↑Fri Nov 03, 2023 7:20 amDRs are never splayed, which is to say placed side by side. They're always vertically stacked. All speakers should be.

Thanks for pointing that out. I was mixing up splayed and stacked. I had stacked in mind and named it splayed. That be me throwing off the disguise and showing that I'm not a native speaker

Keryn O'Shea wrote: ↑Fri Nov 03, 2023 3:17 pmRight yes, I should've said vertically stacked, thank you

Yeah, I was right there with you

first succesfull print with some PLA+ :


it needs some sanding, but it's really nice in fact

i will try with ABS in two or three days but i will makee some individual pieces to assemble the total half horn to avoid warping.

first pair printed !

Kranku68 wrote: ↑Thu Nov 09, 2023 1:07 pm first pair printed !

Looks great. I'd do ABS for sure, then easier to glue together with black ABS cement. What kind of printer do you have? I have a Qidi i-Fast and just got a Creality K1 Max to replace it. Qidi is heated, great for ABS, but i'm going to sell it and get another K1 Max or try a Bambu. We print small parts and K1 is doing a good job at twice the speed.

working with an anycubic kobra plus...nice for big piece of cake...i've got an enclosure system for ABS printing but i must admit that i must push the printer in its physical boundaries regarding bed temperature.

Ok men `that's it...build is finished...they pushed their first shout ever just this afternoon...and my god, that's pretty loud and clear !...nearly a flat eq and everything is very well balanced.
I think i will have to tweak little bit around 10-12k and maybe 3 or 4k but really nothing too serious.
thanks for this 2x8" version Bill

Good to hear!

Congrats on the completion

I'd love to see some pics!