BMS 4592ND performance on a 250Hz tractrix

The sim is slightly different, the 18sound sims look very smoothed, you will also notice my sim goes to 20khz the 18sound is zoomed in and starts at 500 and only goes to 10k. Stretched and zoomed in to that range they are very close. Outside of that range is where the issues lie.

There is also the fact that this sim is a scaled up 2" version, the 1.4" sim is almost identical tho.

Edited by SouthwestCNC - 06 March 2017 at 5:01pm

SouthwestCNC wrote: The sim is slightly different, the 18sound sims look very smoothed, you will also notice my sim goes to 20khz the 18sound is zoomed in and starts at 500 and only goes to 10k. Stretched and zoomed in to that range they are very close. Outside of that range is where the issues lie. There is also the fact that this sim is a scaled up 2" version, the 1.4" sim is almost identical tho.

They do only advertise constant coverage (not directivity) from 1.5kHz upwards but it is most common for isobars to be smoothed, often 1/3rd oct with colours stepped for 3dB divisions.

If you're comparing then it's best to keep the parameters the same.

Takes a lot of processing power and memory (edit: ram) (60gb plus) to go up to 20k in comsol, may be that they didn't have it at the time.

What would your thoughts be on using a tractrix to say 7k below were beaming starts to occur with a non coaxial mf compression driver in addition with a cd flare to handle the high frequencies.

Edited by SouthwestCNC - 06 March 2017 at 9:01pm

Could well be. That's incouraging if so as comsol is very close at 500-10k. Then I ask why have they stopped at 10k? But proofs in the pudding we know it beams as csg experienced, if it's a measurement they have stopped at 10k for a reason.

But like you say they claim constant coverage not directivity. I was under the impression that was the same thing but obviously not, what does constant coverage mean?

Edited by SouthwestCNC - 06 March 2017 at 9:35pm

It suggests that measurements were made using their ND1480 driver on the horn in the PDF. Also as I read it the 10kHz mark on the isobars is not at the far right of the diagram? So it shows response above that - likely up to the 12.5kHz they claim directivity is maintained up to.

Look at isobars / directivity info for most manufacturers, you'll see they all tend to crop to show the 'relevant' parts. It's fairly rare to see data below 400Hz.

SouthwestCNC wrote: Ahh missed that bit, well spotted. Yes I understand there's no point in plotting outside of specified response but even at 12k they are 8k off the top end. Which to me says the recommended response is 500-12k

Well yeah, that's basically what they say…



Edited by toastyghost - 06 March 2017 at 10:00pm