Originally Posted by jpmst3
Agreed, that might not be easier. In fact, perhaps to the contrary.
Is there any advantage to having more folds rather than the dead space?
It would seem the horn path is longer not leaving the dead space...what do the extra folds due to the response curve?
From Danley's Labhorn notes:
Still more complication, at the point where the wall area is a significant acoustic
size, the sound pressure couples to the width mode resonance (caused by the parallel
walls) which puts the first in a series of notches in the response coming out of the
mouth. In this situation, there is a 1/2 wavelength standing wave with the pressure
maxima at the walls and velocity max in the center. Coupling to this mode saps off
energy at frequencies related to the N 1/2 wavelengths. Here, your horn mouth width
(where it has parallel walls) also kind of sets your upper frequency limit. For a 21
inch wide horn like the LAB sub, the first width mode notch should be in the mid 300's
which is a non issue.
He's talking about the horn width there but the same thing applies to the segment lengths when there are parallel walls on each end. The longest a physical segment with parallel walls at each end can be before risking notches in response is about 3 feet. Any longer than that and you could get notches in response down into a typical subwoofer's passband.
For the record, I agree with Ricci. There's nothing I hate more than dead space. It means you could have either better performance or a smaller box. But horn folding is not a trivial pursuit and if you have a choice between a simple fold with dead space or nothing, perhaps it's best to not look a gift horse in the mouth.
Originally Posted by LTD02
... to model it properly would require using akabak, which i don't know how to use.
This program will work as well. http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
And it's much, much easier to use than Akabak. It's even easier to use than Hornresp. A few simple instructions should have you up and running like a pro in about 5 minutes. The only problem is the results are not exactly the same as Hornresp. Very close but not exactly alike. Here's a comparison of a somewhat complex four segment horn done in this program and Hornresp.
The results between Hornresp and Akabak should be identical (as long as the Hornresp sim uses CON segments, which itself could introduce as much difference as the sim pictured above from a Hornresp sim with PAR segments, especially if the segments are long).
Either way, if you (or anyone) needs help with a multi segment sim that Hornresp can't handle I can sim it with either TL.app or Akabak, or at least provide instruction to get you started using TL.app on your own. (If you want me to do a sim though, I require all cross sectional areas at each segment marker and the lengths between them - figuring out this info is the hardest part of the sim.)
EDIT - looks like you figured out an alternative while I was typing. That does eliminate the dead space but I'd still be a bit concerned about potential 1/2 wave notches in those very long segments. But good luck, this looks like a lot of fun.Edited by diy speaker guy - 9/27/13 at 1:17pm