Bandwidth of horns

[angel]

What is the practical maximum bandwidth for a horn, without sacrificing fidelity? Someone on this forum stated that you could only get about 2 octaves out of it, most commercial manufacturers (e.g. JBL) appear to push it to about a decade.

How much quality are you really trading away here?

And, is it feasible, or even possible, to achieve a bandwidth of two decades? (E.g. use a wideband driver in a tractrix contour, operated from 300Hz to 30kHz)

I'm considering playing around with some ideas I got, and I am just a bit curious about how many horns I will need to get decent performance.

[Charles Hansen]

Originally posted by angel
And, is it feasible, or even possible, to achieve a bandwidth of two decades? (E.g. use a wideband driver in a tractrix contour, operated from 300Hz to 30kHz)

You can do just about anything you want (if you know how). You will see lots of theoretical equations that show an upper frequency limit (I'm assuming you already know about the lower frequency limit that is determined by the size of the horn). However these upper frequency limits, while using accurate equations, ignore two real-life factors that can extend the upper frequency response quite a lot:

1) The equations only look at total radiated power. But you mostly care about on-axis frequency response. The power response (predicted by the equations) can be rolling off at high freqencies while maintaining flat on-axis frequency response because the dispersion is narrowing.

2) Once the diaphragm enters break-up mode, all bets are off as far as trying to predict the frequency response (with or without a horn).

The bottom line is that there are several horn designs using one-way (Lowther-type) drivers that are good from 150 Hz to 20 kHz.

Good luck, though -- it won't be an easy project!

[zobsky]

the other option you have is rear loading the (usually single) driver to augument the bass response. the mids and highs are directly radiated.

this is the way to go, IMHO, if you want to keep things relatively
simple.

[roddyama]

I've used a few different JBL and TAD compression driver and horn combinations over the years and I run them less than a decade. Usually less than 3 octives. The possible exception is the TAD 4001 which can go to 4 octaves and still sound good. WRT to the 5th octave, I never liked the sound of a compression driver below 1000Hz so my opinion is that their not capable of carrying that 5th octave. I currently run my TAD's from ~1200Hz to ~12,000Hz.