Eliminating Internal Waves

villeneuve · 14th February 2009, 01:10 AM

Hi guys,

I've heard from a few sources that the actual cabinet dimensions (proportional) can have a large impact on sound quality, due to the nature of internal waves.

The speaker cabinet i'm currently constructing apparently has this problem to the extreme, because the internal depth of the cabinet is a microscopic 64mm, and it is a floor standing speaker. (Effective internal height is 580mm.)

I cannot change the design of the enclosure, so i have to find a way to eliminate these waves.

The products i have available are:
Sound absorbing polyester urethane acoustic tiles
Bitumen based sound deadener acoustic material
25% P.V.C. 75% Barium mineral powder attenuating/reflecting sound barrier material (light or heavy duty)

Which would be the best product (or combination) for this application?

Thanks

DaveCan · 14th February 2009, 02:45 AM

Although it would take up some internal real estate, you could add some spheres, or abstract bracing here and there to break things up somewhat.

Dave

Nedrex · 14th February 2009, 11:44 PM

I think Dave is right. Since your choices are either absorption or diffusion, a combination of both may be the best approach. Sadly, 64mm doesn't give you much room to play with.

Something akin to this:

http://accessories.musiciansfriend.c...ser?sku=422615

Would be nice, but would be hard to execute given your lack of depth. You might want to try raised areas with alternating heights and distances between them as a means to repress the formation of standing waves. Once you put together a formation that sounds better, then cover it with whatever absorbtion material you like.

gedlee · 15th February 2009, 03:44 AM

Quote:

Originally posted by villeneuve
Hi guys,

I've heard from a few sources that the actual cabinet dimensions (proportional) can have a large impact on sound quality, due to the nature of internal waves.

If you use a good amount of absorbing material inside, the shape is not going to be a factor at all. Diffusion isn't going to do much of anything inside of the speaker.

HiFiNutNut · 15th February 2009, 07:08 PM

I am afraid with 64mm internal depth, little can be done about it.

The best damping material I have found is natural wool. Wool batts used for roof insulation is relatively cheap and available.

Regards,
Bill

14th February 2009, 01:10 AM	#1
villeneuve diyAudio Member Join Date: Jan 2009	Eliminating Internal Waves Hi guys, I've heard from a few sources that the actual cabinet dimensions (proportional) can have a large impact on sound quality, due to the nature of internal waves. The speaker cabinet i'm currently constructing apparently has this problem to the extreme, because the internal depth of the cabinet is a microscopic 64mm, and it is a floor standing speaker. (Effective internal height is 580mm.) I cannot change the design of the enclosure, so i have to find a way to eliminate these waves. The products i have available are: Sound absorbing polyester urethane acoustic tiles Bitumen based sound deadener acoustic material 25% P.V.C. 75% Barium mineral powder attenuating/reflecting sound barrier material (light or heavy duty) Which would be the best product (or combination) for this application? Thanks

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14th February 2009, 02:45 AM	#2
DaveCan diyAudio Member Join Date: Nov 2005 Location: Moncton NB	Although it would take up some internal real estate, you could add some spheres, or abstract bracing here and there to break things up somewhat. Dave

14th February 2009, 11:44 PM	#3
Nedrex diyAudio Member Join Date: Feb 2009	I think Dave is right. Since your choices are either absorption or diffusion, a combination of both may be the best approach. Sadly, 64mm doesn't give you much room to play with. Something akin to this: http://accessories.musiciansfriend.c...ser?sku=422615 Would be nice, but would be hard to execute given your lack of depth. You might want to try raised areas with alternating heights and distances between them as a means to repress the formation of standing waves. Once you put together a formation that sounds better, then cover it with whatever absorbtion material you like.

15th February 2009, 07:08 PM	#5
HiFiNutNut diyAudio Member Join Date: May 2004 Location: Sydney	I am afraid with 64mm internal depth, little can be done about it. The best damping material I have found is natural wool. Wool batts used for roof insulation is relatively cheap and available. Regards, Bill