Back Loaded Horn Calculations

[Tyimo]

Hi!

I read the great article about "Design of a Back Loaded Exponential Horn" by MJK and I would like to simulate some comercial horn design.

I don't understand something in the horn lenght calculating equation:
"....the horn’s length is calculated using Equation (5.1) after setting the throat

Lhorn = ln(Smouth / Sthroat) / m

Lhorn = ln(181.6 / 1) / 1.837 m-1

Lhorn = 2.831 m = 111.5 in......"

What does it mean : "In" ??

Another question: how can I measure the correct horn lenght of the Fostex 166 BLH cabinet? I mean what about the bends? Will the line longer or shorter with bends?

Is this horn linear or exponential?

Tyimo

 

[John Sheerin]

It's not "IN", it's "LN", or natural log, as in log base e.

Going by the centerline around the bends is probably close enough in my experience. As long as the dimensions are acoustically small, the wave will go around the bend somewhat intuitively. For example:
http://ldsg.snippets.org/HORNS/images/roundbend/WE30154_1k6.jpg

and:
http://ldsg.snippets.org/HORNS/images/roundbend/random_100hz.jpg

 

[Tyimo]

Thanks for the help John!

I already find this "LN bottom" on my scientific calculator...

Tyimo

 

[Tyimo]

Hi!
Has somebody any idea how could I "bend" an existing straight 40Hz exponential horn in "Carfrae styel"?
How could I calculate the geometry?

Greets:

Tyimo