Hey Jim. You did something very different with the cabinet that is similar to the SS9.5 Was this a cosmetic or functional choice? I’m curious in part because of another thread that is “discussing” enclosure designs. Thanks.
I'll try to make this as short as possible. It has to do with diffraction control.
When sound leaves a driver, it tries to go in all directions. High frequency sounds have a wavelength that is too short to go completely around the cabinet. So those frequencies reflect off the front baffle and are directed outward. As frequencies get lower, their wavelengths get longer. Deep bass frequencies have wavelengths so long that they bypass the cabinet edges altogether and go completely around the cabinet.
You can hear this if you stand behind a speaker while it is playing. You can clearly hear bass and a good deal of midrange, but not much treble.
So what happens when the wavelength of a frequency equals the distance from the driver to the edge of the cabinet? Think of it like wind hitting the edge of a building. There is turbulance created at that frequency that is referred to as "edge diffraction." You can see this in measurements. (How audible are they? That is a question for another day.)
The easiest cabinet to build is one that is rectangular and has 90-degree front edges. That is why you see so many speaker designs with no edge treatment at all. All of these types of cabinets will create a maximum amount of edge diffraction - not ideal. So what do you do about it?
There are a few ways to deal with edge diffraction.
The first is to off-set drivers. The idea here is that the distance from the driver to the cabinet edge on the left side is different than the distance to the right side. The edge diffraction will then occur at two different frequencies, but with half the amplitude for each. So the impact of those diffraction artifacts will, overall, be less.
Another diffraction control remedy is to round-over or chamfer the cabinet edges to provide a smoother transition, creating less distortion in the process. You see this on almost all of our speakers to some degree or another.
Another option is to slant the cabinet edges, or do a graduated round-over or chamfer as you see in speakers like the SS9.5's and BePure 2's. Building cabinets this way is a much more complicated and labor-intensive way of dealing with diffraction issues, but has several benefits.
First, it utilizes the benefits of round-overs or chamfers. In addtion, it also continually varies the distance from the drivers to the cabinet edges, spreading the remaining artifacts over a range of frequencies with very little amplitude for each frequency.
While this edge treatment offers many benefits, there is a down-side related to cost. Instead of having to veneer five cabinet panels (front, rear, top and two sides), you now have three (BePure 2) or five (SS 9.5) additional surfaces to veneer and each takes a few hours to accomplish. But to us, it makes sense on higher priced models to do everything you can to take advantage of the performance of the high end drivers used in those designs. And, in my opinion, it has aesthetic benefits as well.
I hope that made sense.
- Jim
