Horning a cone-based midrange driver...

[Lee in Montreal]

I would think you need a much longer horn and perhaps an exponential configuration to get a response that low.

Indeed. Depth and horn perimeter dimensions will need to be recalculated. Hence this thread. The wave length of a 200Hz frequency is 1.7m, meaning a mouth that could be sized (2:1 ratio) at around 28.5cm tall x 57cm wide (11.2" x 22.5"), and as my 4530 bins are 24" wide, I don't mind adapting the horn to 12" tall x 24" wide and 186Hz cut-off. Depth would be 18" for 1/4 wave of 186Hz. But hey, I still need to read from many sources to ensure I understand properly some of the even most basic principles...

[Joe Alesi]

Hello Lee

180 to 7k is a 5 and a half octave range, although it's generalising there are many horn enthusiasts that will suggest 3 octaves as a max.

180 to 7k is a challenge with the LE5-2 and certainly as has already been pointed out in this thread, too wide for the edgar horn which was typically 400-4k ish from Edgar's plots. To achive your required low freq extension the horn would need to be longer and with a wider mouth to load down lower. Even when this is done you are still faced with the prospect that the the LE5 or 104 will be handling a signal at or below its resonant frequency. This will cause an attendant and very significant rise in distortion, depending on the horn and the SPL/excursion required. One way to offset this may be to use multiple drivers to reduce the drive to each speaker and hence excursion. I was once going to/may still explore this very avenue with a collection of LE5-2s i've gathered. I have a great pic that sparked the idea. I see if I can find and post it.

It's also interesting to note that even in the relatively short edgar horn the HF response on the LE5-2 is reduced significantly and dies at 4k. A phase plug may help somewhat, but I can only see the requuired longer horn making this worse and more beamy.

As a possibility and with experimentation, reduction in output, a careful/steep crossover and the right horn it may be possible to achieve your goal with a JBL 2480 2482 or 2485. maybe even 2490 (although I dont recall its HF extension)

There is also a 100dB sensitivity Audax midrange that might be usable (in some way). It has an fs of 110 Hz or so and a recommended range, as a direct radiator, of 500-8k.

I like the idea of the 2480/82 - especially as I'd like trying the same thing. Using components I already have. I've thought of a using a 2480/82 driving a DIY horn, which then coupled to the throat of a JBL 4560 I have.


Best
JA

[macaroonie]

Hey there Joe hows things. Best regards Mac

[Steve Schell]

Hi Lee In Montreal,

For years in the 1980s and early '90s I read Dr. Edgar's articles in Speaker Builder and noted with interest his location close to mine in southern CA. Might he be approachable, I wondered? Then I met a friend of his at a ham swap meet who arranged a visit to his home and we have been good friends ever since. He has often published his home phone number, so I don't think I'm speaking out of turn to mention it here. If you would like to know his most recent thoughts on any of these subjects, just give him a call at (310)370-1302. He is still manufacturing horn flares for hobbyists in his home workshop just as he was doing when I first met him.

[Hoerninger]

Just trying to understand how a horn will affect frequencies.

1. Horn dimensions (for exp-horns), a set of equations

2. "JBL's New Maximum Output Midrange/Low Frequency Transducers" (page 3)
Some equations for frequency limitations based on Thiele-Small Parameters

-3db at 2*(fs)/QTS , any upper linear extension is not horn based but due to cone based directivity.
____________
Peter

[Joe Alesi]

Hey there Joe hows things. Best regards Mac

Hello Mac,

All is well on this end, except for slugishness with all my audio projects. How is it all for you?

Mods- Apologies in advance for OT chatter.

Best
JA

[Lee in Montreal]

Seeing that it will be difficult to reach sub 200Hz with a horn loaded 104h-2, I investigated and found an 8" driver that has a frequenccy span between 50-15Khz which I intend to use from 130Hz to 7Khz. Not horn loaded. I will reuse a 1cft enclosure that I had initially built for some 2218J (which tops at 3Khz, and not a good match for anything but a 2402).

The 2115A is 8 Ohms and has an Alnico motor.

http://www.lansingheritage.org/image...2115/page2.jpg

1cft enclosure with 2118J