2397 horn - varnish and adapter

[gerard]

HI

Nice drawing .
I will advise when I will first finish the 2397 ....

Gerard

[speakerdave]

Widget has done great ground work on adapting a 1.5" driver to the 2397 and similar horns. On another thread where this came up Earl raises interesting theoretical questions which suggest that the horn and driver are best designed as a whole.

On a related question I have been wondering if the 4" diaphragm 2447 and the smaller 2435, both of which have a 1.5 opening, use the same horn? I don't see anything in the JBL literature that suggests they can.

David

[Earl K]

Hi Dave

re; mating the 2435 to the 2397.

FWIW;

(a) If it was my project, I'd ask Ken Pachkowsky to take an internal lip to lip measurement of the 1" Smith Horn, as found in his Westlakes.

(b) Then I'd look the Mr. Widgets' measurements to derive the average height
inside the more or less horizontal part of the H9800 diffraction portion of that horn.

(c) Then, see if you can get a measurement of the diffraction Slot-Opening for the large Vertec SR box that uses the 2435.

(d) Take a measurement of the ( 2397 ) height between the top & bottom plates.

(e) Compare these four figures. Some design commonalities should come to the forefront. What to determine ; The best ratio of ;Compresson Driver throat exit size to distance between the top and bottom horizontal lenses.

Some History :

The predecessor to the Smith type horn is the "parabolic horn" as described by H. F. Olson ( of RCA ) in the mid fifties. Drawings show a virtually identical horn - though minus any internal vanes. I believe the aspect ratio he used was .5, when comparing the drivers' exit size to height between horn bells. It's the velocity buildup that occurs when forcing sound through a smaller apeture, then followed by presenting a wide low-pressure horizontal zone, that forces the sound to spray and spread. The reason a one exit driver coupled to the 2397 doesn't work is because little to no pressurization actually happens. Additionally, the 2327 adpater goes the wrong direction from a pressure perspective.

My Conclusion : I'd be thinking that I need to shrink the mouth height somewhat for this Smith horn ( for use on a 1.5" exit driver ).

Just my thoughts

<> Earl K

EDIT : Alex has asked ; What are the purposes of the vanes in the Bell ?

The original parabolic horn without the vanes shows great dispersion in the upper regions. The book has polar patterns included. It's in the lower octave that dispersion suffers ( without the vanes ). This leads to an assumed conclusion that just can't be tested till someone makes ( & tests ) a large Smith Horn without Vanes. It might be worthwhile to ask Ken if the small 1" Smith Horns ( in his Westlakes ) have vanes .

[Ken Pachkowsky]

The small Smith horns on my Westlakes have no vanes and are 13 x 3/4 inches at their widest point.

[Ken Pachkowsky]

The small Smith Horn is used from 4.5K to 20K but drops off very fast after 16K. They are powered by a JBL 2426H

Ken

[Earl K]

Thanks Ken !

SLOT:
- Did you already state it as being 3/4" - if not - again, what was the height of the slot ?

Thanks <. Earl K

[Ken Pachkowsky]

My fault, was not clear.

The opening is 13 inches wide by 3/4 of an inch tall.

Ken

[Earl K]

[Alex Lancaster]

Love that leery Westlake smile.

[Ken Pachkowsky]

I just purchased a pair of 2405 alnico's that I ill be adding to the HR-1's. Widget convinced me this could be an interesting experiment.

Ken

[jandregg]

Ken,
What is the distance from the throat to the front lip. Just trying to picture the overall shape. Thanks. John

[Ken Pachkowsky]

The distance from the throat to outer lip is 9 1/2 inches measured at the center.

Ken

[S Boat]

Good evening gentleman



I bought myself a JBL 2397 with the intention to quarter it; scan it to solid works then sent the G codes to my CNC router and make (4) for my boat. Yes boat. Trust me you have not lived until you ride the ocean swells out of the sight of land at 50+ with a 110 db masking the sound of the wind rushing by. Just raw awsom but it takes power and efficiency to do it and that means horns, clean smooth horns.

I Anyway went on line looking for 2328-2327 throat sections and found your site, Seems you all are already on the trail.

I need to drop to 1" because at this point I am attempting to milk suficent high frequancy without seperate hi frequancy horns.

Right now I am tri amped 31hz to 90hz then 90 to 1000 up.

Chasing wooden horns for warmth of tone as boats by nature have very hard reflective surfaces.


Anyone see any reason not to just CNC the horn and adapters all one piece, actually make two open halves and glue them together?

Thanks
Don

[Mr. Widget]

I've beat you to it. Send me a PM with your e-mail and I'll send you the 2397 as a Solid Works file.

I'd stick with the 2328 due to the structural requirements to support the very heavy 2" throat drivers. I'd also highly recommend you step up to the 2" exit drivers as they are really necessary to get the full potential of that horn. The 2327/2328 combo with a 1" driver sounds very honky. With the 1" exit driver you loose the warmth you are after... it isn't due to the metal either... I've made wooden and plastic adapters.

In the thread below you'll notice that I did thicken the outer section though.

http://www.audioheritage.org/vbullet...read.php?t=695


Widget

[mpaschetto]

Hi Mr. Widget!

I sent a PM regarding the CAD files!

Mike