Where to start for back loaded horns

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Sorry it took so long to respond, I thought I had already posted it and was waiting for the mod approval until I realized I hadn't posted...


Hello,
l = meter
AL = area in sqm at the wished point l. INV ln (l*k)*AH=Al

k = 4pi * frequenz / c
c ~ 340, pi ~3,14

Thanks for clarifying.


Well, I know hm is trying to be helpful but perhaps the OP should read this first and maybe the valuable but cryptic replies will make more sense.

http://www.quarter-wave.com/Horns/Back_Horn.pdf

BTW, no matter what you may read torea, BLH design is well defined from a modelling point of view, but there is little consensus on what the design targets or overarching design philosophy should be. There is no substitute for getting Hornresp, spending 1,000 hours learning how to use it well (time well spent) and doing it yourself.
The MJK worksheets are also a Gold Plated investment if BLH's figure in your future.


Haha ironically, trying to read that pdf was what brought me here. I felt like I was getting completely lost reading it so I figured I must be missing out on some fundamentals or something. I'll read it a couple more times and see if it starts coming together.

I guess I'll have to finally get around to installing Windows.


Thanks!
 
I agree that there is no real substitute for building 'em and building 'em again.

I'll second that motion. Go find some nice and easy build plans like a Makizou clone or a Buschhorn, and build it out over a couple weekends. Then you have something to listen to while you read up on the theory and exercise the simulations while you design your "big one". At least, that's my strategy. 😀
 
Yes go for building something that you find resonable size wise. Models will tell you a lot of how it will measure and how it will sound "quantity" wise. But quality wise these simulations does not tell the whole story. Something that sim poorly will most likely sound bad but a good sim does not ensure good sound will emerge from the horn
 
Another 2 cents worth:

Differing personalities/inclinations/skill-sets make people approach the hobby from various directions.

I am a dreamer and a hands on type---maybe a strange combo. But I am not too good at math. So I started BLH design by studying existing popular, small designs on the internet; and started drawing lots of fanciful pictures.

Long story, short version, I came up with a seat-of-the-pants analysis of what makes a good expansion for my popular driver, the Fostex FE126e, and for other similar drivers. Some popular/successful small horns seemed to use similar expansions(Buschorn, Horneshop,Cheap trick, as I recall from 5 years ago)

So I made a 1/4 scale cardboard model that represented the expansion for a given (parallel-sides) depth of cabinet-It just looked like a skinny, tapering piece of tag-board, with notes on it. Then I just had to multiply width and length by 4 to know how wide the horn was to be at a given point down the horn. You could do basically the same thing with a chart, but with the model you can measure at any point and get a value to work with, and it is cool to be able to visualize the look of the flare.

The first horn I built sounded pretty good. Some subsequent ones work really well.

I did get pretty inventive with details, and with basic design. I turned the cabinet so that the driver was on the flat side, and made it wider at the bottom, to help with baffle step and physical stability, and to make it sit close to a wall. I tried to make it with as few pieces as possible, so that I could produce them for sale, which I have not done.

The Fe126e version ended up being mass loaded by virtue of a restricted mouth; which gave more bass. The FE 206 version has a "full" sized mouth that fires down to the floor around the perimeter of the base(plus a proper mouth out one side), but also has a 8"PR. on the back side. Both are on the small side for the driver they use. Both sound good.

If you are not quick at building things, and want to end up with something that is nice to listen to, it is probably best to go by proven plans. If you are smarter than me(in appropriate ways), and are good with math, maybe you will have a lot of fun designing by more abstract methods.
 
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