Enclosure Wall Thinkness

malcolmfraser · 02:04 AM

Hi all, just thinking, about thickness

Looking to build a good quality set of bookcase speakers to run off a 12watt PP EL84 amp I am building.

Just getting into the design and looking at enclosure material. I have some very old, very dense and very hard native timber (New Zealand Rimu about 75 years old).

Its 45mm thick, so nothing like 25mm MDF!! Width is 225mm and I have about 6meters of the stuff

I am assuming this would be great to use as it won't vibrate at all, and would look truely amazing.

I am also assuming that this would suit a fully enclosed design, opinoins? Looking for top end/reference quality design....
-
Any thoughts, and possible designs/plans?

gooki · 5th November 2010, 07:11 AM

45mm should be fine, feel free to internally brace if you want. As for designs - 6 meters should be sufficient for a pair of bookshelf speakers. Though you'll have to adapt a design as very few enclosures use such thick walls.

FWIW I'm using 18mm solid Rimu for a low powered compact speaker.

malcolmfraser · 5th November 2010, 09:53 AM

Quote:

Originally Posted by gooki

45mm should be fine, feel free to internally brace if you want. As for designs - 6 meters should be sufficient for a pair of bookshelf speakers. Though you'll have to adapt a design as very few enclosures use such thick walls.

FWIW I'm using 18mm solid Rimu for a low powered compact speaker.

Thanks Gooki, I guess the key 'measurement' is the internal volume when compared to the driver spec..

More to follow...

Helmuth · 11:33 AM

I think the thick walls are nonsense.

18mm does fine. My experience is that internal bracing is more effective as thick walls. tap the walls with a wooden stick and listen.

And use bitumen damping to make it dead. I would go for extreme bitumen damping as for extreme thick wooden walls.

Heavier material will not vibrate fast but when it is vibrating it has a lot of energie stored. So light and strong material is the best.

Like birch plywood good self damping light and strong.

McCormack · 5th November 2010, 05:44 PM

There's a reason that the better sounding commercially available speakers generally use thick, heavy enclosure walls, and my personal experience of having built both thin and thick walled speakers bears that out.

buggsson · 5th November 2010, 06:45 PM

I've been told that it also has to do with the frequencies in question and the wall materials self resonances as well. According to this approach you use light, stiff and well braced wall materials for the lower frequencies and heavy stuff for the upper freqs. and really heavy. I've heard recommendations for 1000 times Mms.

5th November 2010, 02:02 AM	#1
malcolmfraser diyAudio Member Join Date: Sep 2010	Enclosure Wall Thinkness Hi all, just thinking, about thickness Looking to build a good quality set of bookcase speakers to run off a 12watt PP EL84 amp I am building. Just getting into the design and looking at enclosure material. I have some very old, very dense and very hard native timber (New Zealand Rimu about 75 years old). Its 45mm thick, so nothing like 25mm MDF!! Width is 225mm and I have about 6meters of the stuff I am assuming this would be great to use as it won't vibrate at all, and would look truely amazing. I am also assuming that this would suit a fully enclosed design, opinoins? Looking for top end/reference quality design.... - Any thoughts, and possible designs/plans? Last edited by malcolmfraser; 5th November 2010 at 02:04 AM.

5th November 2010, 11:29 AM	#4
Helmuth diyAudio Member Join Date: Oct 2008 Location: Winterswijk	I think the thick walls are nonsense. 18mm does fine. My experience is that internal bracing is more effective as thick walls. tap the walls with a wooden stick and listen. And use bitumen damping to make it dead. I would go for extreme bitumen damping as for extreme thick wooden walls. Heavier material will not vibrate fast but when it is vibrating it has a lot of energie stored. So light and strong material is the best. Like birch plywood good self damping light and strong. __________________ ( (( KUGELWELLE )) ) recent projects :OB-mk1 /fatboy / monitor-xl / Horn-AM / dappolito / td124-mk1-rb301 / Hybrid-pse / Vfet Last edited by Helmuth; 5th November 2010 at 11:33 AM.

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5th November 2010, 07:11 AM	#2
gooki diyAudio Member Join Date: Dec 2008	45mm should be fine, feel free to internally brace if you want. As for designs - 6 meters should be sufficient for a pair of bookshelf speakers. Though you'll have to adapt a design as very few enclosures use such thick walls. FWIW I'm using 18mm solid Rimu for a low powered compact speaker.

5th November 2010, 05:44 PM	#5
McCormack diyAudio Member Join Date: Mar 2006 Location: SE Wis	There's a reason that the better sounding commercially available speakers generally use thick, heavy enclosure walls, and my personal experience of having built both thin and thick walled speakers bears that out.

5th November 2010, 06:45 PM	#6
buggsson diyAudio Member Join Date: Sep 2005	I've been told that it also has to do with the frequencies in question and the wall materials self resonances as well. According to this approach you use light, stiff and well braced wall materials for the lower frequencies and heavy stuff for the upper freqs. and really heavy. I've heard recommendations for 1000 times Mms.

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