Hi all,
I have two JBL 2360 horns, and in the (near) future I want to purchase 2 CD's for them. What strikes me is the shape of the 2" horn entry, see the image below. It is certainly not circular (top to bottom: ~51mm, left to right ~47mm). Both of them look the same. Seeing this got me thinking: is it worth to invest in 600 euro drivers like the BMS or B&C coaxials for this horn? It feels a bit like using a highly advanced tight toleranced driver attached to a horn of the 'olden day's'. (Don't know what I get myself into by saying this) 🙂
Hopefully some of you can share their experience with this horn and/or give some insight of the effect of coupling a perfect circular 2" CD to this horn entry.
Thanks!
I have two JBL 2360 horns, and in the (near) future I want to purchase 2 CD's for them. What strikes me is the shape of the 2" horn entry, see the image below. It is certainly not circular (top to bottom: ~51mm, left to right ~47mm). Both of them look the same. Seeing this got me thinking: is it worth to invest in 600 euro drivers like the BMS or B&C coaxials for this horn? It feels a bit like using a highly advanced tight toleranced driver attached to a horn of the 'olden day's'. (Don't know what I get myself into by saying this) 🙂
Hopefully some of you can share their experience with this horn and/or give some insight of the effect of coupling a perfect circular 2" CD to this horn entry.
Thanks!
That's the same for almost all the big horns of that time from EV, JBL, others too. Check first if it's somewhere in the opening already too wide. If it isn't, mark the overhang of it and use a dremel or a file to make it even.
If it's too wide already, put a 2mm alu plate on it (instead of a driver), transfer the screw holes (make it a bit bigger, then you don't have to cut a new thread), glue it full surface on the flange, put it on a level surface pour epoxy in the opening (calculate the volume first, thickness of the flange x surface of the opening) from the mouth with a dropper. Let it then cure, then bore the 2", smoothe (sanding) the edge and it's better than new.
If it's too wide already, put a 2mm alu plate on it (instead of a driver), transfer the screw holes (make it a bit bigger, then you don't have to cut a new thread), glue it full surface on the flange, put it on a level surface pour epoxy in the opening (calculate the volume first, thickness of the flange x surface of the opening) from the mouth with a dropper. Let it then cure, then bore the 2", smoothe (sanding) the edge and it's better than new.
Is that JBL or a copy (PAudio etc.), as the CAD file from JBL shows a circular entry, file attached, rename to *.dxf after downloading.
Yes, this horn can reach the bottom of the speech band (300-400Hz) and besides its size, this (diffraction) horn doesn't have many issues.
Yes, this horn can reach the bottom of the speech band (300-400Hz) and besides its size, this (diffraction) horn doesn't have many issues.
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Your concern is the reason that waveguiding is the topic it has been lately. This doesn't mean that horns like this are bad.. we're talking degrees here. However this kind of throat does kind of bring into question the benefit of a good phase plug.
The pinch is correct but I think the OP's concern is that the his/her horn's entry is not circular with a 50mm (or 25mm) diameter. The first picture shows an oval entry instead.
Indeed, it is not circular.
Thanks for all replies, and DIY-dremel it is 🙂 . I think there is enough material to make it circular with a diameter of 2".
I am pretty confident these are not copies.
Thanks for all replies, and DIY-dremel it is 🙂 . I think there is enough material to make it circular with a diameter of 2".
I am pretty confident these are not copies.
No need, any reflections back to the phase plug would be well above the driver/horn's audible BW.
Hello,
the throat untry indeed has a strange egg like form. The theoretically it should be perfectly round. Is there maybe some kind of damping pad that overhangs?
The horn itself belongs to the so-called category of radial diffraction slot horns. So the intention is to do some wave front forming in the throat region to reach a slot radiator. I like this design because it is a coherent wrt to the wave front. But beyond the slot the horn open up suddenly and this produces a discontinuity in the impedance with all it's known issues, and you may hear this. I would rate these horns not really as HiFi, but they surely served their job well at their time wrt what they had been designed.
If you plan to buy the CDs only for these horns, then I would start with a used pair and first test if you like the combo.
You will have the privilege of doing the secondary finish work on a JBL sand cast throat 😉
The JBL 2360, 2365, 2366 bi-radial horns each required a different throat casting.
The older radial series, the 2350, 2355, 2356 and the 2397 "Smith" horns all used the same 2328 sand cast throat adapter.
None of the castings were exactly the same, and the finish varied quite a bit, though your 2360 throat looks worse than the any 2328 that I recall.
Art