21 inch long throw horn

I'm in the process of designing an 18 inch FLH to replace the SBH (the SBH is a design from the 90s, it was rejiggered to work with 'modern drivers' in like 2007, end result is badly optimised and doesn't work well with actual modern drivers).

I have been playing with the idea of designing a 21 inch FLH once I'm finished. A 21 has pretty much no advantage over an 18 in a FLH other than the fact that it can displace more air so can it take more power before it runs out of xmax. I might call it the 'Compensator' because... if you are not trying to compensate for something, why would you build it?? 



Edited by citizensc - 01 April 2021 at 8:41am

Stuff some coats in the mouth. 

APW i know a couple of cabs won’t play very low I’m just being realistic with my budget ideally I’d like to build 12 of them and I certainly would be re contributing them back into the scene I’ve already got a full sound system dedicated to the sw free party scene (although it’s currently in the nick after boxing day )

https://file.io/58crMXmKFlpM

levyte357- wrote: Lost count, of how many times, I've been completely underwhelmed by 21" FLH subs. I guess expecting solid 40hz, from stack of 4x cabs, is unreasonable. What I think would be really clever, is modding Martin WSX design, so it doesn't throw too far, for inside venues. A driver with higher Xmax, High BL, and maybe larger chamber in cab, would not require such a long horn,and possibly such tight throat/compression.

Before you try that, you might want to do some research into how subs actually work, and why they aren’t “throwing” the sub into the car park...

Likewise actually conducting some measurements to figure out how you achieve what you like. You’d be amazed (or not) by how few people can identify low frequencies when they are actually being played. Conditioning and other factors typically mean that harmonics are considered as a fundamental, and many FLH will filter those harmonics out by their very nature.

That doesn’t make them objectively bad, just not suited to your personal preferences. That said - yes, I agree - designs like the SBH are far from optimised. Hornresp usage seems to be the golden rule for many of these things; it’s a great tool, but it only tells a tiny part of the picture.

If you want to see things done properly, you should look at Scott Hinson’s recent work on his dual 18” FLH over on the DIYRM Facebook page.

Likewise, there are 21” FLH done properly out there. The stuff from Sean Hennessy, for a start. If you’re not keen on something the size of a Battleaxe, then the dimensions of the PG21XL he did for Pure Groove work too. Although loading those things is a pain in the arse beyond compare, even if you’re used to F218s...

The other issue is the simple fact that thermal limits kick in well before excursion or otherwise. People push these things far too hard without considering the acoustic impedance of the combined horn, and the space that they’re placed in. Let alone the wavelengths involved.

Judging a whole loading concept by a few DIY designs, most of which are invariably run without proper processing, is not doing anything remotely close to scientific analysis or engineering.

Edited by toastyghost - 05 April 2021 at 1:09pm

jacethebase wrote: To be fair, changing the laws of physics would be very clever.