Big ass midrange horn project

[Lee in Montreal]

So, I purchased some throat adapters for a JBL 2360, and seing how costly and difficult it is to ship some fiberglass 2360s, I have decided to make my own horns. The 2360 has two diffraction points. The vertical point is at the driver, while the horizontal point is 2/3 toward the exit. I think that my design has only one point. Area is 36" horizontally, and 24" vertically. The mouth has a 112Hz cut-off with a 226Hz horn length (1/2 wave). No clue how diffraction and spread will work ;-) And it should be a short throw.

[Steve Schell]

Hi Lee, I like your drawings a lot. You adhere to a principle I hold dear, that horns need to be as large as required to do their jobs well. This size horn will provide what I like to call "big goose bump" vocal reproduction. You have drawn basically a radial horn, with two straight and two bent sides. John Volkmann of RCA invented this type in the 1930s, to combine the fine loading of an exponential flare and the excellent directivity of a conical (straight sided) horn. Normally the horizontal pattern is optimized by placing the straight sides left and right, while the expansion rate is provided by the curved upper and lower sides and the directivity sacrificed in this less important axis. You have reversed these roles, and can expect a very consistent pattern in the vertical axis, one that narrows with rising frequency in the horizontal. This would normally not be ideal, so you might consider a redesign, retaining the same expansion while reversing the shapes of the two pairs of sides. In any event you will come out ahead of the 2360 biradial, which IMO has diffraction problems caused by the sharp breaks in the flare.

[ivica]

So, I purchased some throat adapters for a JBL 2360, and seing how costly and difficult it is to ship some fiberglass 2360s, I have decided to make my own horns. The 2360 has two diffraction points. The vertical point is at the driver, while the horizontal point is 2/3 toward the exit. I think that my design has only one point. Area is 36" horizontally, and 24" vertically. The mouth has a 112Hz cut-off with a 226Hz horn length (1/2 wave). No clue how diffraction and spread will work ;-) And it should be a short throw.

I think that "horizontal" beaming would be too high, so 90 deg. rotation of the horn would be may be better.

Owing to the relatively long almost parallel planes, I wonder what would be the frequency response over say 8kHz...
Regards
Ivica

[Lee in Montreal]

Hey Ivica. You are correct. Unless I add a pair of diffraction areas, the horizontal will be beamy. after all, there's a reason why the 2360s look like that.

57489

On anoher sad note, there's a dude in Ohio who has a shitload of 2360 horns. But being difficult and expensive to ship, he already sent many sets to the dump to be crushed... If anyone in Ohio wants to pick some horns for cheap, here's your chance.

http://www.diysoundgroup.com/images/large/JBL_cabinets.jpg

http://www.diysoundgroup.com/images/large/JBL_horns.jpg

http://www.diysoundgroup.com/images/large/JBL_fun2.jpg

[baldrick]

Recently there were (I think) 17 sets of 4675 (with 2360/2446 and dual 15s) for sale in Norway as well, they were sold for aprox $500/pair :blink: I didn't belive my eyes when I visited the stock they were stored... but all of them are gone now.

[wrager]

57489

On anoher sad note, there's a dude in Ohio who has a shitload of 2360 horns. But being difficult and expensive to ship, he already sent many sets to the dump to be crushed... If anyone in Ohio wants to pick some horns for cheap, here's your chance.

http://www.diysoundgroup.com/images/large/JBL_cabinets.jpg

http://www.diysoundgroup.com/images/large/JBL_horns.jpg

http://www.diysoundgroup.com/images/large/JBL_fun2.jpg

Isn't that Eric : http://www.diysoundgroup.com/flat-packs-1/subwoofer-flatpacks-1.html ?

[Lee in Montreal]

Yes

http://www.avsforum.com/t/1317390/big-jbl-theater-items-for-the-diy-guy

[ivica]

So, I purchased some throat adapters for a JBL 2360, and seeing how costly and difficult it is to ship some fiberglass 2360s, I have decided to make my own horns. The 2360 has two diffraction points. The vertical point is at the driver, while the horizontal point is 2/3 toward the exit. I think that my design has only one point. Area is 36" horizontally, and 24" vertically. The mouth has a 112Hz cut-off with a 226Hz horn length (1/2 wave). No clue how diffraction and spread will work ;-) And it should be a short throw.

Hello Lee, If You have decided to make your own large mouth horn, why not to try to make something like "Quadratic Throat" or ("Oblate Spherical") so to reduce diffraction (if possible) either on the driver mouth (==horn throat) and along the horn, while reaching desired horizontal and vertical angles, but keep in mid the results Mr.D.B. Keele has explained in Patent_US4071112, in order to reduce mid-frequency beaming as explained in "What's So Sacred About Exponential Horns" while construction the EV HR9040 horn. I do believe that all of such Mr. Keele work is well known to You, too, but for the other forum members:

http://www.xlrtechs.com/dbkeele.com/PDF/

http://www.electrovoice.com/sitefiles/downloads/EV_PABible-07-Add06-Constant_Directivity_White_Horn_Paper-1980.pdf


As we can see, to day, may of the mentioned work has been applied in the Everest2 H66000 horn design. Regards Ivica

[Lee in Montreal]

Short update on the project.

I have sent out drawings to laser cut the vertical and horizontal "stencils" I will use to cut the panels with a router. Templates are cut in 1/4" aluminum. I am using a small router with a 1/8" bit with a ball bearing.

The horn design is bi-radial with a diffraction area midway thru the horn for 85° horizontal dispersion. Size is 34" horizontally by 25" vertically. Total depth with 2440 drivers is 36". Expected cost to build the horns (pair) shall be around $50.00 + Shellac and paint. Throat adapters were $50 each w/ shipping. Big ass horns for under $150.00 pair and one day of my time.

Target is a 500Hz 12db crossover point. With hoperfully "useable" 350Hz.

[ivica]

Short update on the project.

I have sent out drawings to laser cut the vertical and horizontal "stencils" I will use to cut the panels with a router. Templates are cut in 1/4" aluminum. I am using a small router with a 1/8" bit with a ball bearing.

The horn design is bi-radial with a diffraction area midway thru the horn for 85° horizontal dispersion. Size is 34" horizontally by 25" vertically. Total depth with 2440 drivers is 36". Expected cost to build the horns (pair) shall be around $50.00 + Shellac and paint. Throat adapters were $50 each w/ shipping. Big ass horns for under $150.00 pair and one day of my time.

Target is a 500Hz 12db crossover point. With hoperfully "useable" 350Hz.

Hello Lee,
It would be nice to "see" the results of such huge beast, may be horizontal angle over 90 deg in order to prevent internal "wall-to-wall" reflections.

Regards
Ivica

[Lee in Montreal]

Hello Lee,
It would be nice to "see" the results of such huge beast, may be horizontal angle over 90 deg in order to prevent internal "wall-to-wall" reflections.

Regards
Ivica

Horizontal walls will be basically like in post #4 with a radial expansion.

I'll make sure to post pictures when the first unit is assembled.

[Ruediger]

There was an article "The Manta Ray Horns" in the JAES. You can purchase that article - or buy the Anthologies of the JAES about loudspeakers. I recommend that, there is plenty of papers about all aspects. If You look for the article's date You can tell in which of the anthologies that article is and just buy that one.

Ruediger

[sir.byrd]

How's this coming along, lee?

[Lee in Montreal]

Not much time available for the moment. So I bought some JBL 2360 in the interim.

http://www.audioheritage.org/vbulletin/showthread.php?34120-JBL-2360-new-install&p=344680#post344680

http://sphotos-e.ak.fbcdn.net/hphotos-ak-ash3/883001_550757838288922_1701708698_o.jpg