BillFitzmaurice.info

From "Speaker Builder's Loudspeakers for Musicians":

"...100% efficiency can only be reached with a horn one wavelength long, with an opening (the mouth) one wavelength across."

Ohmergerd. Why haven't I ran across this in all of my rambling reading on the net? (Cause you're not an engineering student in audio, that's why.) Nonetheless, does a system of that configuration provide a 100% efficient (essentially) system? If so, then what percent efficient is say a 27" wide T-60? 4%? (Considering the number of doublings of mouth diameter that would have to occur before it was 1 wavelength across.) And are the T-60s horn length a wavelength long, or only 1/4 ?

On this note: What if a horn were constructed that were TWO wavelengths wide; the volume of air would be at least double. Would this cause most drivers to shatter their cones from the increased pressure, thus requiring 2 (or more) drivers?

And would there be any benefit to a horn being LONGER than one wavelength?

Now the whole "1 wavelength long, 1 wavelength wide" bit may seem obvious to you Bill, but it sure wasn't to me. Are there some other little gold nuggets like that you'd like to offer up? It sure helps with the big picture in understanding this whole science.

Rich4349 wrote:From "Speaker Builder's Loudspeakers for Musicians":

"...100% efficiency can only be reached with a horn one wavelength long, with an opening (the mouth) one wavelength across."

100% efficiency was the wrong choice of words, maximum sensitivity and low frequency extension is what I should have said way back then. The actual sensitivity of a 'perfect' horn is in the vicinity of 50%, ours average around 25%, as opposed to perhaps 5% for the best direct radiators. There's nothing substantial to be gained by going longer than 1 wavelength, and even 1/2 wavelength gets you a very good result. We use 1/4 wavelength horns, as even those are as long as we need to do the job while still being able to fit them into a building, let alone move them. The general exception is with high frequency horns, where you can go 1/2 or even 1 wavelength without being too large.

Would making the horn mouth wider than 1 wavelength make the horn louder at its given frequency cutoff?

Rich4349 wrote:Would making the horn mouth wider than 1 wavelength make the horn louder at its given frequency cutoff?

In Bill's words, I believe he states it would be more sensitive.

if the box is square it is the perimeter (the inner perimeter) what should measure that one wavelenght right??