9 replies to this topic

[shizzle]

Heya,

I remember reading a while back on Gary Biggs award winning regal the use of diffraction rings used on his mids.

A quote from the article :
"here is one other little trick Biggs used on the midrange driver in the front stage. Doug Winker, an acoustical engineer at JBL, designed a "diffraction ring." What this ring does is help minimize the secondary lobes coming off the side of the speaker. The ring is made of aluminum and starting just past the surround, a star-pattern is cut from the center. The teeth are of a random shape and size. There is serious engineering behind the rings' design, too much to get into here, but it seems to work for Biggs."

Pic (albeit bad) :  Gary.jpg   19.86K   7 downloads

Now, my question is I was wondering if something like this would be advantageous to do, and if so (which it would seem to be), does anyone have any idea where to start?
I need to make some grills up for my mids in the kicks, and could incorporate the design into the grill easily, if I had a stating point.
I am not really into trial and error, so any input is appreciated.

Cheers,

[Pulse-R]

Similar designs have been used in home audio also.
The theory is to reduce the off-axis dispersion so the reflections from walls and floor are reduced, or at least controlled.

In-car this corresponds to under-dash, doors, and any other nearby surfaces. The effect I think it would have is to make the early reflections lower in magnitude, thus enhancing the primary sound, adding focus and stability to the centre image.

[Pulse-R]

[shizzle]

yup, seems to make sense.

Now the million dollar question, how does one go about designing one?

[syd-monster]

trial and error, the only non-variant seems to be it extends from the edge of the cone. Soo.... get ya hands dirty and do a comparison.

[br85]

It's a waveguide (literally, it guides waves). It's just a different way to go about achieving the same end goal as a more traditional "horn shaped waveguide". The difference being that instead of using all smooth surfaces, it uses all jagged ones. Reminds me of the two different methods used with stealth planes (some use no jagged edges whatsoever, some use all jagged edges).

[shizzle]

cool, thanks for the info. I guess I can try it with some thick'ish plastic. Will let you'all know how I go.

Cya

[zion187reigneth]

shizzle, on Dec 12 2009, 12:10 AM, said:

Now the million dollar question, how does one go about designing one?

quantum mechanics

or a calculator and some heavy aluminium foil

[shizzle]

Maybe I can make a nice tin foil hat with the rest of the foil

[zion187reigneth]

shizzle, on Dec 17 2009, 06:23 PM, said:

Maybe I can make a nice tin foil hat with the rest of the foil

no point getting expensive for a proto type