DIY 500Hz Smith Horn? Please help me design one!

[mpaschetto]

Hi Guys!

I've searched through the archives, and read successful accounts of scaling down the Smith horns for a higher cutoff frequency. However, I've yet to see any information about scaling UP a Smith horn for a lower cutoff frequency.

Has anyone tried this yet?

Is it simply a matter of following the formulas in the 'Distributed-Source Horn' article? If so, I'll plow through the math to get a good starting point, but I'd need a recommendation for the throat area (So). I'd like to use a mouth thickness (t) of 2" for better integration with my 2" compression drivers.

One more question:

Exactly what is the throat area (So) Smith refers to? Is it the starting area of one of the individual cells?

Thanks in advance,

Mike

[hapy._.face]

Is it simply a matter of following the formulas in the 'Distributed-Source Horn' article?

Beats me- Ken or Widgett might chime in here. Or you could PM them; I'm sure they have an answer for you.

[JuniorJBL]

Dr. Widget

Knows quite a bit about this "area"

[Fred Ireson]

I'd like to know too how to lower cutoff - width's no problem

also - are there any followup to Johnny's 5Khz Smith-horn? don't understand the pointy conical thing in his drawing

Old Article


http://www.audioasylum.com/forums/HU...ges/98507.html

[yggdrasil]

I'd stick with rescaling the JBL 2397.


When entering the numbers into the spreadsheet it gives you a radius of 62cm/24,5 inches. The horn will then be ~ 110 cm/43 inches wide.

[Fred Ireson]

thanks Johnny - 43 inches - haha - might do something funny with power response & EQ needs too (?)

do 1" format Smith load OK to 800Hz?

heres one with a funky Peavey 22A
http://img216.imageshack.us/img216/3853/shgjpg9or.jpg

Best,
Freddy

[Flemming Skov]

Hi Guys!

I've searched through the archives, and read successful accounts of scaling down the Smith horns for a higher cutoff frequency. However, I've yet to see any information about scaling UP a Smith horn for a lower cutoff frequency.

Has anyone tried this yet?

Mike

Hi Mike,

Any progress in you search for a smith horn construction details? I have a pair of 2380 horn to start with but have relized that vocal sound is a bit "closed" or "in a box" like, so to say (Ido not EQ them).

For me it seem that a smith horn is the way forward so I am also looking for construction details regarding a smith horn for 500 Hz as the low and used with the 2445 driver to xover at 7kHz to my 2404. I have build a set of corner horn. Any interested see the link:
http://forums.klipsch.com/forums/thread/741550.aspx

Regards Flemming

[ralphs99]

I guess my first reaction is to ask why?
The Smith horn is an attempt at getting high frequencies to disperse better. The wavelengths at midrange frequencies are long enough that beaming is no longer a problem.
In fact containing midrange frequencies is more of a problem than spreading them out. I'm not sure how well a Smith horn can control midrange directivity.
Cheers,
Ralph

[Steve Schell]

Hi guys,

I thought I had posted the original article by Dr. Smith, "A Distributed-Source Horn" on the forum in the past. I couldn't find it in a search however, so here it is. Note that Dr. Smith mentions that his design was to be used above 750Hz., even though it has an exponential flare constant of 375Hz. This is very conservative design of the old school, no doubt intended to avoid the response ripples of a finite exponential horn down near cutoff. My guess is that his design could be reworked for a 2" throat and a slower flare rate and still have a reasonably compact horn. Smith horns were built to cover different frequency ranges in the 1950s; I have seen pictures of at least one system using three different sized Smith horns plus a woofer section.

People are often confused by what looks like a rounded triangular section in the throat in the drawing. It is only there to show the angles of the "torpedo" dividers, not to indicate a solid structure.

Sorry for the crummy photocopy- not my work. I have the magazine, so if there is interest I can make better scans from the original.

[Zilch]

JBL dimensions here:

http://www.jblpro.com/pub/obsolete/2397.pdf

See below for one approach to the recommended "lips."

[Flemming Skov]

Steve,

In the text is noted 2 formula's for each calculation. The last formula using inches as the text says. Do you know if the first formula is expressed in the S - I unit system (metric) ? I will try to calculated one for xover at 500 Hz. The JBL2397, if looking in the data sheet, is measured at 500 Hz so it seem that this horn is capable of producing sound at that low frequency. Is it recommanded to use the JBL2397's overall measures in designing a new horn? Does anybody know?

Regards
Flemming

[jacopuzzo]

Hi guys,

I thought I had posted the original article by Dr. Smith, "A Distributed-Source Horn" on the forum in the past. I couldn't find it in a search however, so here it is. Note that Dr. Smith mentions that his design was to be used above 750Hz., even though it has an exponential flare constant of 375Hz. This is very conservative design of the old school, no doubt intended to avoid the response ripples of a finite exponential horn down near cutoff. My guess is that his design could be reworked for a 2" throat and a slower flare rate and still have a reasonably compact horn. Smith horns were built to cover different frequency ranges in the 1950s; I have seen pictures of at least one system using three different sized Smith horns plus a woofer section.

People are often confused by what looks like a rounded triangular section in the throat in the drawing. It is only there to show the angles of the "torpedo" dividers, not to indicate a solid structure.

Sorry for the crummy photocopy- not my work. I have the magazine, so if there is interest I can make better scans from the original.

Hello,
I'm trying to build a Smith horn and it would be very helpful if you could send me some better scans of the article.
Thanks in advance

[hjames]

Hello,
I'm trying to build a Smith horn and it would be very helpful if you could send me some better scans of the article.
Thanks in advance

Whoa - that post was from almost 2 years ago!
There are other scans of Smith Horns in the forums - best bet is to do a Search for them and see what you come up with - ... like this:

http://audioheritage.org/vbulletin/s...earchid=964154

or THIS!
http://audioheritage.org/vbulletin/s...ht=smith+horns

and then check THIS!
http://audioheritage.org/vbulletin/s...ht=smith+horns

Lotsa info here!