If a baffle is 2 meters wide, what is the frequency where the sound
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 31st July 2004, 07:48 PM #1 454Casull   diyAudio Member   Join Date: Jan 2004 Location: Toronto, ON, Canada If a baffle is 2 meters wide, what is the frequency where the sound fires completely into 2pi space?
 31st July 2004, 10:16 PM #2 Equilibrium diyAudio Member     Join Date: Oct 2002 Location: Mad Dog, Texas divide the speed of sound by 2 meters 340/2=170 170Hz give or take depending on air pressure and temperature more or less
 1st August 2004, 12:43 AM #3 GM   diyAudio Member     Join Date: Jun 2003 Location: Chamblee, Ga. Hmm, 'sound is round', so assuming a round baffle to keep it simple and SoS = 344.424m/sec, then as a rough approximation: 344.424/pi/2 = ~54.82Hz/F3, but there's a terminus end correction of radius*0.613 that needs to be accounted for: 344.424/pi/(2+(2/2*0.613) = ~41.96Hz. If F6 is what you're looking for, then it is 1/2 octave away, or 41.96*0.707 = ~29.66Hz. Or just use Linkwitz's formula for F6: (0.17*344.424)/2 = ~29.28Hz. I assume the inaudible discrepency is due to him rounding the numbers off a bit in his lumped sum value. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
 1st August 2004, 02:41 AM #4 Hybrid fourdoor   diyAudio Member     Join Date: May 2003 Location: Ft. Worth, TX So...so far we got 144Mhz, 170Hz, and 42Hz. Anyone else???? You know how this scientific stuff is "Industry, science, and technology! Big men putting screwdrivers into things! Turning them! And adjusting them!"
 1st August 2004, 03:21 AM #5 Hans L   diyAudio Member     Join Date: Apr 2004 Location: Planet Earth F3 of 42Hz and fully into 2pi at 170Hz is pretty close. However, this is all theory. With these kinds of frequencies in a room, you will probably get completely different results due to roomgain and standing waves. __________________ In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move. --- Douglas Adams
Svante
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Join Date: Feb 2004
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Quote:
 Originally posted by Hybrid fourdoor So...so far we got 144Mhz, 170Hz, and 42Hz. Anyone else???? You know how this scientific stuff is "Industry, science, and technology! Big men putting screwdrivers into things! Turning them! And adjusting them!"
Depending on how you define "fully" all answers are correct. Unless you really mean fully (ie nothing gets around to the back side), then the answer is "infinite".
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 1st August 2004, 03:34 PM #7 pinkmouse   diyAudio Moderator     Join Date: Apr 2002 Location: Rotherham, England rcavictim Your comments are inappropriate for this forum, and not required here, so I have removed them to Texas. Please behave from now on or further action will be taken. __________________ Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
rcavictim
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 Originally posted by pinkmouse rcavictim Your comments are inappropriate for this forum, and not required here, so I have removed them to Texas. Please behave from now on or further action will be taken.
Well 'ya see officer......here I was in the proper lane doing the speed limit when someone says "2 meters". Just so happens that triggers a nerve because I do care and am most concerned with the direction where amateur radio is going. I apologize for posting clearly off topic.
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454Casull
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Join Date: Jan 2004
Quote:
 Originally posted by rcavictim Well 'ya see officer......here I was in the proper lane doing the speed limit when someone says "2 meters". Just so happens that triggers a nerve because I do care and am most concerned with the direction where amateur radio is going. I apologize for posting clearly off topic.
What does a distance of 2 meters have to do with amateur radio?

GM
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Join Date: Jun 2003
Location: Chamblee, Ga.
Quote:
 Depending on how you define "fully" all answers are correct. Unless you really mean fully (ie nothing gets around to the back side), then the answer is "infinite".

Hmm, obviously I was not thinking in terms of F0 WRT 2pi space radiation, but it would be 1/2 octave above F3, or 1.414*~41.96 = ~59.33Hz, so I don't see how ~170Hz or any other frequency 'up' to 'infinite' can be correct, especially since 'infinite' as I understand the term = DC.

GM
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