The shorting ring is probably the only distortion (I'm only talking non-linear distortion here) in a loudspeaker that is highly audible at reasonable listening levels and this is easily explained. From my study of distortion (see my web site) I know that higher orders of nonlinearity are the most important (its not 2nd harmonic that you are hearing, more likeley 4th of higher) and the shorting ring acts on the full bandwidth of the signal, not LF dominated like any excursion related distortion. My point is simply that drivers in which nonlinear distortion is not a factor are readily available. I would never consider ANY driver without a shorting ring - its simply a given IMO.

Another study that we did was on the audibility of distortion in compression drivers - both linear and nonlinear. Bottom line is (the deatils wil be published shortly) that nonlinear distortion in a compression driver is irrelavent - no one could hear any in any driver up to the drivers thermal limits - and these were 4" high power units. So at reasonable levels nonlinear distortion is irrelavent in compression drivers and most other drivers I would suspect. I always say that distortion in a driver is not the issue, overdriving it is. So long as it is not overdriven nonlinear distortion is negligable. If you can actually hear distortion then you have the worng speaker - too little output capability. Get a bigger one.

There's one way to get 90o directivity from a single LF source, and that's to put it into a corner. Other than that, a free-standing basshorn can't because it isn't large enough. Room corners can provide 90o directivity because the walls are large enough to direct the wavefront.

About distortion, I can always hear the difference between a driver with an effective shorting ring and I think you're right about the reason why. Even-order harmonics are suppressed well up into the midrange. Flux control rings aren't usually made big enough to do a particularly good job at very low bass frequencies, but they work great from midbass through the midrange. The power range I'm talking about is from about 1% to maybe 25% or so, maybe as high as 50%. For a 600 watt driver, between 10 watts and 100 watts, the difference between one with an effective shorting ring and another similar unit without a ring is clearly audible.

Merry Christmas!

Wayne

I am not sure that I agree that a corner is a good 90° horn. Sure it loads better at low frequencies, but at above about the Schroeder frequency I don't think that you can view a corner as a controlled directivty source.

I can't see any reason why the Schroeder frequency would be any sort of upper limit for directivity control. If anything, it's the very low frequencies where even the relatively large dimensions of the walls would become too small for pattern control.

It's a mute point though I suppose because most voice-range systems aren't corner loaded, as they are too far from the corner apex. It's the bass system, up to about 200Hz, that I'm referring to when I speak of corner loading.

1. Doesn't directivity apply mainly to horns? What about smaller cone speakers that are highly efficient, like the fostexes, and the older alnico speakers?

2. Maybe it's the dynamic range of the speakers that makes them sound more live (the ability to jump from 95 db to 105 db on some recordings, without losing steam)?

thanx
-akhilesh