Standing waves in midirange encloser and pyramids on encloser's walls-what dimension?

GrzMiL · 7th April 2006, 11:08 PM

Hi

I was thinking abou placing pyraminds on inner walls of enclosure of midirange and i would like to know what is the relation between the pryamid's wall length and height and length of wave that is reflected by this pyramid (the longest way that it can disperse effectively).
For example:
If the midirange is crossed at 500 hz then (simplyfying) the longest wave length will be 68cm ( of course in small midirange enclosure it won't make a standing wave and it won't act as a wave). What should be dimensions of the pyramids on the wall to effectivly disperse reflecting wave and therefore standing waves.

Thx in advance.

Tenson · 8th April 2006, 01:00 AM

You would probably be better off making something like the RPG Skyline inside the cabinet. Designed properly it should give equal harmonic amplitudes where as a pyramid just re-directs quite crudely, reacting differently to different wavelengths. I.E. the frequency response of the reflected sound will remain more even with a properly designed diffusive surface rather than some pyramids.

I'm not sure if it really matters that much but with a load of different size 2x2" pine it would be easy to make. I can't remember how to work out the sizes needed for a desired frequency range but have seen it about.

BTW, for 500Hz you are looking at, at least 9" deep per cabinet wall.

JohnL · 8th April 2006, 01:36 AM

I know the mods sometimes get upset about cross posting from other forums, but somebody else did the work on this one and I'd feel wrong just copying it. There is a great deal of good info at this link.

Diffusor Info

pinkmouse · 8th April 2006, 07:32 AM

Good link. I knew I had seen a diy project for the "skyline" panels somewhere.

Oh, and we have no problems with links to useful material like that.

GrzMiL · 10th April 2006, 06:05 PM

JohnL
Thx for link, i found a lot of useful info.

7th April 2006, 11:08 PM	#1
GrzMiL diyAudio Member Join Date: Jan 2005 Location: Poland, Cracow	Standing waves in midirange encloser and pyramids on encloser's walls-what dimension? Hi I was thinking abou placing pyraminds on inner walls of enclosure of midirange and i would like to know what is the relation between the pryamid's wall length and height and length of wave that is reflected by this pyramid (the longest way that it can disperse effectively). For example: If the midirange is crossed at 500 hz then (simplyfying) the longest wave length will be 68cm ( of course in small midirange enclosure it won't make a standing wave and it won't act as a wave). What should be dimensions of the pyramids on the wall to effectivly disperse reflecting wave and therefore standing waves. Thx in advance.

8th April 2006, 07:32 AM	#4
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Good link. I knew I had seen a diy project for the "skyline" panels somewhere. Oh, and we have no problems with links to useful material like that. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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8th April 2006, 01:00 AM	#2
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	You would probably be better off making something like the RPG Skyline inside the cabinet. Designed properly it should give equal harmonic amplitudes where as a pyramid just re-directs quite crudely, reacting differently to different wavelengths. I.E. the frequency response of the reflected sound will remain more even with a properly designed diffusive surface rather than some pyramids. I'm not sure if it really matters that much but with a load of different size 2x2" pine it would be easy to make. I can't remember how to work out the sizes needed for a desired frequency range but have seen it about. BTW, for 500Hz you are looking at, at least 9" deep per cabinet wall.

8th April 2006, 01:36 AM	#3
JohnL diyAudio Member Join Date: Apr 2004 Location: Tampa, FL	I know the mods sometimes get upset about cross posting from other forums, but somebody else did the work on this one and I'd feel wrong just copying it. There is a great deal of good info at this link. Diffusor Info

10th April 2006, 06:05 PM	#5
GrzMiL diyAudio Member Join Date: Jan 2005 Location: Poland, Cracow	JohnL Thx for link, i found a lot of useful info.

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