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An apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL. -
Re: Driver Size, Off-Axis
It's hard to put an exact number on it, it depends on cone diameter, cone profile, etc, but it's not important to be ultra precise and there's a ROF which states that beaming will start to occur at roughly 13550 / cone diameter (inches).
PCD will visually show you the estimated off axis behavior.Don't even try
to sort out the lies
it's worse to try to understand. -
Re: Driver Size, Off-Axis
PCD requires Office.
13550/6.5 = 2,084
Correct?
I guess other factors play a big role, because this guy is -5dB @ 1,500........
http://www.parts-express.com/pe/psho...4-1146&scqty=2An apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL.Comment
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Re: Driver Size, Off-Axis
Use Google books to get to Sound System Engineering by Don Davis, Eugene PatronisOriginally posted by icor1031 View Post
page 264 has the formulas"Not a Speaker Designer - Not even on the Internet"
“Pride is your greatest enemy, humility is your greatest friend.”
"If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."Comment
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Re: Driver Size, Off-Axis
Thanks, impressive.
Also,
This book uses -6dB.
Isn't that way too low? Shouldn't it be -3 at most?
Originally posted by Sydney View PostAn apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL.Comment
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Re: Driver Size, Off-Axis
I'm not sure how to answer that as I don't know what your goal is...Originally posted by icor1031 View Post"Not a Speaker Designer - Not even on the Internet"
“Pride is your greatest enemy, humility is your greatest friend.”
"If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."Comment
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An apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL.Comment
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Re: Driver Size, Off-Axis
Yeah, best to listen to Sydney, apparently I'm not thinking clearly this evening and I gave you the wrong ROF. Since getting to page 264 on my slow dial up isn't going to happen in this lifetime and I can't even download the driver spec sheet at the moment I did a quick search for beaming start frequency.
On this forum they frequently use the formula 11500 / driver diameter (inches).
In other places on this forum and around the web it's stated as 1/2 (or 1) wavelength. (The formula I gave describes 1 wavelength.)
But I suspect (and PCD seems to back this up) that the on axis response starts to diverge from off axis at around 500 hz or so, which is ~1/4 wavelength of a 6.5.Don't even try
to sort out the lies
it's worse to try to understand.Comment
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Re: Driver Size, Off-Axis
As mentioned ( in post 2 ) it is difficult to come up with an exact figure, because the theoretical calculations are based upon a flat piston, which a speaker cone isn't. A particular cone may be designed to affect dispersion.
Additional discussion:
page 13 - 16 of Loudspeaker and Headphone Book by John Borwick
page 64 of Electroacostical Reference Data by John Eargle
Note what happens when Ka > 1"Not a Speaker Designer - Not even on the Internet"
“Pride is your greatest enemy, humility is your greatest friend.”
"If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."Comment
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Re: Driver Size, Off-Axis
Here's a visual answer to your question...
Looking at the plots, clearly when the driver is asked to reproduce wavelengths significantly longer than it's diameter, it does so very well... with wide dispersion.
The dispersion gets much worse as the wavelengths approach the diameter of the driver.Comment
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Re: Driver Size, Off-Axis
Anyway, PCD shows response is -3 db at 80 degrees at approximately 1500 hz for an actual measured cone diameter of 5.5 inches (which should be ~accurate for a 6.5 inch driver.
(I should know this stuff better by now, I just had a very similar conversation a couple of months ago.)Don't even try
to sort out the lies
it's worse to try to understand.Comment
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Re: Driver Size, Off-Axis
That is a lovely graph... It also makes me want to redo my project, but I don't want to build a 4-way.. lol..
Originally posted by ReissM View PostAn apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL.Comment
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An apostrophe with an "s" does not mean plural.
Speaker's IS NOT PLURAL.Comment
-
Re: Driver Size, Off-Axis
Here's what PCD says. For a generic 6.5 inch driver from my files (actual cone diameter 5.5 inches) at 0 and 80 degrees.
Don't even try
to sort out the lies
it's worse to try to understand.Comment
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Re: Driver Size, Off-Axis
Check out the directivity graphs on that SEOS-12 and a B&C DE250, they're pretty darn good. I think I might build 7 speakers for HT with them.
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