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purplepeople 19th February 2005 12:47 AM

Baffle step theory
 
Hi everyone,

Other than the usual suspects, like Elliot, King, Murphy, Unruh, et al., are there earlier or other papers on baffle step theory?

I've been looking at whatever's at hand on the web and some questions have come up:

1) Since the drivers that can produce the wavelengths in question are typically at least 3" in diameter, why does the generic theory seem to assume baffle measurements based on the driver's center as opposed to the edge of the radiating surface?

2) What happens to the non-point source waveform as it transitions from the driver to the baffle? Is there a blurring of the wavelength as it "slides" sideways along the baffle?

3) If the driver is mounted in a very tall and thin rectangular baffle, should there be a calculation for the short dimension and one for the long dimension?

4) Should there be a corresponding calculation for any enclosure openings that have SPL output?

5) Would it be significantly more accurate to attempt a calculation that accounts for the shape of the entire outer edge of the baffle?

6) What compromises are being made in the generally accepted calculations?

7) Would an "idealized" external stuffing damp the ripples of the 4pi transition for baffles with large height/width ratios?

Any resources or opinions would be highly welcome.

:)ensen.

knorke 19th February 2005 07:48 AM

You might want have a look to this:
http://www.tolvan.com/edge/

planet10 19th February 2005 11:23 AM

Re: Baffle step theory
 
Quote:

Originally posted by purplepeople
7) Would an "idealized" external stuffing damp the ripples of the 4pi transition for baffles with large height/width ratios?
At the wavelengths you are dealing with relative to the width of the baffle, you'd probably end up with a speaker looking like a sumo wrestler :)

dave

purplepeople 19th February 2005 07:40 PM

knorke
I've downloaded that Edge simulator but haven't run it yet. It appears to model the driver as a complete surface rather than a point source. The examples listed on the webpage appear to flatten the ripples completely and create a perfect mirror step, as if they are also optimizing something.

Dave
That sumo analogy might be a little unwieldy. Are you thinking about the sumo suits. Tall thin guy dressed up in the baggiest fluff-filled outfit.... like the Michelin Man.

Based on the relative quiet, I'd have to guess that the acoustic theory is either highly proprietary or plenty good enough with the current set of assumptions.

I will try the optics or sonar people and see if they have anything.

:)ensen.

knorke 19th February 2005 08:04 PM

Hi purplepeople,
Quote:

I've downloaded that Edge simulator but haven't run it yet. It appears to model the driver as a complete surface rather than a point source. The examples listed on the webpage appear to flatten the ripples completely and create a perfect mirror step, as if they are also optimizing something.
You can set the number of pointsources which edge uses to model the speaker.
You can set it to 1 which gives you actually a pointsource but then the simulation will not take the beaming towards higher frequencies into account....

planet10 19th February 2005 08:17 PM

Quote:

Originally posted by purplepeople
That sumo analogy might be a little unwieldy. Are you thinking about the sumo suits. Tall thin guy dressed up in the baggiest fluff-filled outfit.... like the Michelin Man.
Yes... you need on the order of a 1/2 wavelength of material before it absorbs....

dave


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