Best way to fold a horn??...

You need to fold around the mid point of the horn's cross section. I don't know how to do it with sketchup, but here's a good explaination of how to do it with autocad, and the principles involved.

http://www.centauriaudio.com.au/diy/hornfold.html

Kieran

Yeah i probably should've mentioned that I read that several times, and also the stuff on this forum about calculating the area before and after the bend (in the guide to hornresp and winisd topic), but I'm really aiming for sketchup level kinda stuff. I dont know autocad and im time restricted so learning it isnt feasable at the moment.

'it is adding extra length to my horn, length that would be destructive to the final frequency response in relation 
to my simulation.'

Folding a horn will increase LF response slightly at the cost of HF response.

I didnt have autocad and refused to 'obtain it'. So i used qcad 1.5 and just did multiple iterations and learned how long to make each section just by doing it and learning how much path could fit and how it compared to the model.

I wouldnt worry about small 5% errors etc.

According to Tom Danley the path length is actually not quite in the middle as the air mass affects it. But he mentions that approximating your exponential horn as a few conical steps makes no difference in the bass region-which makes things ALOT easier.

http://www.diyaudio.com/forums/showthread/t-80068.html

Nice horns!




Edited by tb_mike - 27 February 2009 at 9:24am

Hi all,

I'm now folding from the center path of my horn expansion, but I have a question, in sketchup how do i create a non-perfect curve. Like if I use the curve tool and drag it out it eventually creates a perfect circle, but i want the curve to be oddly shaped so that it matches my horn expansion if that makes sense. Here's a couple of print screens of the fold i've created.

Before the fold from the center path:


After I've created the fold:


Heres a quick edit in photoshop to illustrate what i mean. The blue getting darker represents an increase in horn width from the inside edge, the further toward the horn mouth you get (or corner, since this is a fold):





Edited by James.L - 03 March 2009 at 3:37pm