Speaker design myths revealed

Fiddler...Please tell us all about your open baffle system.

Placing the driver in the center of a circular baffle will produce increased non-linearities in response. This is due to the consistent spacing in all directions of the baffle and the baffle related diffraction / reflections that take place. If using a circular baffle, the driver should be slightly offset. This causes a staggering of center frequencies that the diffraction related lobing takes place at. Radiusing the baffle and / or treating it with acoustic damping material can help, but there are tricks to this too.

When radiusing a baffle, the radius has to taper at a very gradual rate in order to achieve maximum effectiveness. Rounding the corners of a flat baffle does little to nothing. It might look prettier and produce "flowing lines", but it does next to nothing acoustically.

According to the studies i've seen, the most linear response from a driver is achieved when placed in an "egg shaped" cabinet with a slightly flattened baffle. This staggers both the quantity and frequency of baffle related diffraction taking place due to the driver having varying distances to the edge on each part of the baffle. The contoured shape minimizes the diffraction that does take place because the reflected sound waves are seamlessly directed away from their source due to the radius of the cabinet.

This is the reason that Waveform used this design on their monitors. The fact that they "textured" the cabinet also helped to break up standing waves on the baffle even further. While i did not personally like specific design aspects on some of their products, they truly were doing some innovative things that nobody else had attempted to conquer. Sean
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TWL, et'al

keep in mind the downside of having the baffle stop reinforcing at one frequency will be a very specific baffle step point. I would use a rectangle or maybe a slightly squished octagon with folding wings to extend the cancelation points toward the bass. What do you think?

Clever dimensioning could help give an extended smoother response. personally i'd at these sizes I'd build a new wall in the room with the drivers mounted in it and be done,

Best bass best everything.

Fiddler, what's an open baffle?
Maybe up against the wall does not ruin left - right imaging but depth sure does suffer IMHO. Interesting what some folks consider a myth. Maybe Jordan is one of those "flat earth guys".
There aren't many speakers that measure as flat as Jordan (at least on axis) and those measurements don't take into consideration the effect of crossvers.
Sean, my computer is so slow I don't always post a link. =:)

From the experience of numerous other people, the baffle does not have to be very large to be effective if you aren't concerned about low bass frequencies. 50-60HZ is about what one could expect with a small baffle (see link below) and the subs come in where the bass begins to roll-off determined by the in-room response of the baffle.

Here is a link with several pictures:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=19883&perpage=10&highlight=lexan&pagenumber=7

And another:

http://www.dietiker-humbel.ch/micromag.htm

There are many more pics and threads elsewhere online about OB, but this is an example of the type of OB I am experimenting with.

I know jack**** about all this, but I trust both my friends and their ears. They both currently have really high-end systems and have been through several other high-end systems. My friend said his OB PHYs wiped the floor with his previous $$K speakers and all who have heard his OB's have been very impressed.