Smooth or stair-cased contour for back-loaded horn

[pixeljedi]

Hey All,

I have a question that's been nagging at me for awhile and can't seem to find the answer to it. Apologies if this has been answered in the past.

I'm designing some new back-loaded horn cabinets for the FE208EΣ driver and I noticed some back-loaded horn builders use a smooth contour for the horn section, while others use the fostex recommended stair-case hard edge contour.

My question is, why use one over the other? I'm assuming it matters

Also, if someone knows a good book they could recommend on the subject, I'd appreciate it.

Thanks in advance!

[TerryO]

Originally Posted by pixeljedi

Hey All,

I have a question that's been nagging at me for awhile and can't seem to find the answer to it. Apologies if this has been answered in the past.

I'm designing some new back-loaded horn cabinets for the FE208EΣ driver and I noticed some back-loaded horn builders use a smooth contour for the horn section, while others use the fostex recommended stair-case hard edge contour.

My question is, why use one over the other? I'm assuming it matters

Also, if someone knows a good book they could recommend on the subject, I'd appreciate it.

Thanks in advance!

I don't believe one has a great advantage over the other. The stair step configuration does provide some muting of what bit of treble may have made it through the horn's foldings. The other advantage may be the aggregate strength and weight that the stair step provides.

The stair steps in the original Japanese designs, were actually a series of vertical bulkheads that were used to contain rounded river rocks.

Best Regards,
TerryO

[rjbond3rd]

Apparently, the rationale is that the stair-step has a low-pass effect, keeping higher frequencies from comb-filtering with the directly radiated output.

I don't know of a book but there are patents, papers etc. Most important thing seems to be a good simulation tool and thousands of hours

Okay, now do tell about this horn you're designing!

[pixeljedi]

Thanks guys,

That makes a lot of sense on keeping the highs out from where they don't belong - thanks!

Right now everything is in sketchbook stage, but I will post when I have things nailed down more (design-wise) and my volume calculations accurate.

Thanks again,
Thor

[Leonidas]

We made the first part ( near the throath) more smooth, and left the lower part with stairgase.
Idea behind it : where the pressure is high , make smooth , where the pressure is lower , reject the mid - parts of the audio spectrum.
Search for the "ibR 108 horn" in this section of this forum, there are pics showing the idea.
Good luck!!