Speaker design myths revealed

No Gregm, no piano hinges.

I am going to experiment with plywood baffles until I find the size of baffle that seems to be optimum and then I will have the baffles made out of Lexan if I like the results of the plywood. It will be a flat baffle with no hinges. Others have had great success with this design.

I have a friend that has just done this and he and another friend said the results have been nothing short of phenomenal. But he used piano hinges, but many others haven't. The open-baffle PHY's may suck in my room, but time will tell.

No additional tweet. The PHY KM 30 SAG has a time-aligned piezo-electric tweet that goes to 30kHZ.

They will require subs for sure.

Fiddler, you can calculate the size of the needed baffle by using the quarter wave formula.

It depends on how deep in the bass you want these things to produce.

Pick a frequency above the F3(resonant freq) of the driver, and deep enough into the bass region to satisfy you.

For example, if you want 32Hz to be able to be reproduced by the system(assuming the driver goes that low), you will need a baffle that is at least 1/4 wavelength of the (32')32Hz wavelength, which would be 8 feet across. If you want to get only to 64Hz(16' wavelength), then you'd only need a baffle that is 4 feet across. If you want to "split the difference, and get 48Hz, then you could use a baffle that is 6 feet across.

All frequencies above the frequency determined by the baffle board will be reinforced by the boundary effects of the baffle board, and will not be subject(much) to the "wrap-around" cancellation effects that will adversely affect the frequencies below the capability of the baffle board to handle.

While it is a matter of discussion whether to mount the driver in the center of the baffle board, due to the relative "smoothness" of the response curve, mounting it in the center would give the best result in getting to the deepest bass for a given size baffle board.

The determining factor(in size) for the baffle board's effectiveness is based upon the smallest outside dimension that goes across the driver. So the smallest outside dimension will dictate your reinforcement frequency, and any larger dimensions will have little effect, but they may do a little. Thus, a circle shape will be the minimum sized shape that you could use, but it is more difficult to stand up and use. A square baffle is typical, but only the largest diameter circle that you can draw around the driver will be doing the work, and the corners doing very little.

Remember, if you make it tall and narrow, you are losing your effectiveness, so make it just as wide as it is tall.

Having the piano hinges, and angling the sides backwards to a small degree will do just as well, and helps to make the baffle more visually acceptable. It also keeps the edges out of the diffraction plane.

The best thing would be to make the whole baffle shape like one of those "snow saucers". It would allow the driver to be placed at the foremost part(center), and have uniform shallow radius sloping backward all the way around, for most smooth response and minimum diffraction. But it would need to be big, and I've never seen a 6 foot snow saucer!

For the easiest construction, flat and square works.

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.