Modifiction to HD15 Flare

general concensus is that 5 straight sections is the closest and easiest way to get very close to the original shape of the curved section. I believe Heathrow B Line did a pdf file which shows you how to cut the wood to get use 5 straight bits of wood instead of the curve. I cant remember the length of each one but the angle was an 81 degree mitre on both ends of each of the 5 panels. If you search in this section you should find i.

edit: found it - http://www.bl-online.org/users/lasse.lukkari/hd215/HD215.pdf
its 124.7mm outside edge and an 81 deg mitre on both ends for the 5.

I dont know if anyone has done a 3 sectioned one before but i doubt it. Have you calculated the change in chamber volumes and horn flair rate?certainly be interested if you have.


Edited by fat_brstd - 20 November 2009 at 12:41am

fat_brstd wrote: general concensus is that 5 straight sections is the closest and easiest way to get very close to the original shape of the curved section. I believe Heathrow B Line did a pdf file which shows you how to cut the wood to get use 5 straight bits of wood instead of the curve. I cant remember the length of each one but the angle was an 81 degree mitre on both ends of each of the 5 panels. If you search in this section you should find i. edit: found it - http://www.bl-online.org/users/lasse.lukkari/hd215/HD215.pdf its 124.7mm outside edge and an 81 deg mitre on both ends for the 5.

Cheers FB: This'll be a plan B

fat_brstd wrote: I dont know if anyone has done a 3 sectioned one before but i doubt it. Have you calculated the change in chamber volumes and horn flair rate?certainly be interested if you have.

Well the chamber volumes wouldn't be a problem to calculate so they're the same as the original HD15, but the horn flare rate is what I'm worried about.
I was planning on just dividing the (roughly) quarter circle into three, so that the joints on the straight parts are equidistant.

I'll get some drawings up of a design proposal, but to be honest I don't have a clue what considerations need to be made concerning the flare rate.

Any advice in this department would be much appreciated.

cravings wrote: i think someone did one where they cut (can't remember how much tbh) about 12mm through a single piece of wood in 4 places and folded it slightly on the cuts.. to get the 5 piece sectional curve.. can't remember who... mykey may have been in the thread, or he may have even suggested it...

Hi Cravings: I tried that but birch ply snaps pretty easily and I'm not really up for MDF. I have access to a good table saw that can cut angles well so I don't have a problem cutting the individual parts and gluing them with PU glue.

HighLift wrote: Does the HD15 flare need to be curved? I've noticed quite a few around with 5 or 6 straight sections making up the  flare but why not less say 3 sections. For example: if the chamber volume is the same as the original curved flare what adverse effects could this have?

None. even if you build it with 3 straight sections

WOW that looks impressive!

I think a 2 section would look cool, much more like a funktion one style band pass just got to make sure the driver fits and the internal volume of the rear chamber stays the same!

<or 1 section might be nice >

djyves wrote: yea 1 section 1 curved section