[ricardojoa]

Hi,

i know that solid wood are more sensitive to whether condition and that the wood can tear.
I know Salk use maple on one his monitor.
So if a customer request for solid wood construction on a cabinet, is it right to say that there is a probable risk of wood contraction that can affect the overall cabinet integrity?

[Ace Deprave]

If I'm not mistaken, the bamboo speakers are solid wood, not veneered.

[srb]

If I'm not mistaken, the bamboo speakers are solid wood, not veneered.

Well, there is such a thing as solid bamboo boards that are carried by some hardwood lumber suppliers, but all of the bamboo speaker cabinets I have seen use bamboo plywood, which although 100% bamboo, is constructed from bamboo strips glued up in a number of different configurations that gives it dimensional stability as well as being available in large size sheets.

Steve

[jparkhur]

Not that these are Salk, but I have had no separation with these, multiple strands of wood/species.  I figured that since they were in a enclosed, and temperature regulated area, no problem.   I have yet to see any grain or butt joint issues.

JP

[jsalk]

Steve is correct.  Bamboo is bamboo plywood.

The problem with straight hardwood is that it expands and contracts with changes in temperature and humidity. 

To understand the issues, look at the way a solid wood door is constructed.  There is a frame with slots in it.  The center panels fit in these slots.  So when the wood "moves" it can float in the slots.  It can expand and contract quite a bit with no major issues.

This type of construction would not work for a speaker cabinet since it needs to be air tight.  So all the panels need to be hard glued to one another.  When the wood expands and contracts, there is nowhere for it to go.  So the cabinet joints are prone to fail and severe warping could also result.

A number of years ago, I purchased a museum-grade piece of Mexican cocobolo.  It cost me $1000.  I split it down the middle in order to get a pair of mirror image pieces for the front baffles of a pair of HT3's.  The speakers were stunning when finished.  Six months later, I had to throw the cabinets way.  The front baffles split and warped so badly, that they actually ripped the underlying MDF cabinet apart.  I was really happy I had not sold this pair to a customer.

If you do use hardwood for a speaker cabinet, there are a couple of things you can do to minimize problems. 

First, select a wood that is relatively stable.  This would generally eliminate burls and woods with wild grain patterns or heavy figuring.  Straight grain and minimal figuring is much more stable.

Second, make sure the wood is well-seasoned.  The wood should be aged (air-dried) for a minimum of one year for each inch of thickness.  The moisture content should be under 6%.  Wood becomes more stable with age.

Use thinner wood panels and perhaps sandwich layers with grain running in opposite directions. I other words, make your own plywood.

Kerf the wood from behind so that only a very thin layer is completely intact.  Fill the kerfs with some inert material (like epoxy) that is stable.

But the best approach is to avoid solid wood all together.  If you don't, you are asking for problems.

- Jim

[jonbee]

Solid wood has been used in furniture and musical instruments for millennia, and if used properly it ages perfectly. The key is not to use wood that has not been dried sufficiently, which takes time, of course. Daedalus uses it to stunning effect. Lou is a craftsman that knows how to use it. There are occasional issues but they are easily handled; in fact repairs are more successful than trying to repair veneers. Most don't use it because it is far more expensive to buy and use properly than veneered mdf.
Of course this doesn't necessarily reflect on SQ. There are great sounding speakers with cabinets made from just about every solid material in common usage, all with adherents. The result is in the province of the designer, not the materials themselves.

[rollo]

   Wood can be used however the expense of doing it properly may be the issue. I'm hearing some talk about using Indonesian hardwood ply as an alternative to MDF.
   Whatever material offers the least resonance and does not warp should work just fine. Salks enclosures are well done and look great. leave it to Jim.


charles

[Ace Deprave]

Well, there is such a thing as solid bamboo boards that are carried by some hardwood lumber suppliers, but all of the bamboo speaker cabinets I have seen use bamboo plywood, which although 100% bamboo, is constructed from bamboo strips glued up in a number of different configurations that gives it dimensional stability as well as being available in large size sheets.

Steve

Steve is correct.  Bamboo is bamboo plywood.

The problem with straight hardwood is that it expands and contracts with changes in temperature and humidity. 

To understand the issues, look at the way a solid wood door is constructed.  There is a frame with slots in it.  The center panels fit in these slots.  So when the wood "moves" it can float in the slots.  It can expand and contract quite a bit with no major issues.

This type of construction would not work for a speaker cabinet since it needs to be air tight.  So all the panels need to be hard glued to one another.  When the wood expands and contracts, there is nowhere for it to go.  So the cabinet joints are prone to fail and severe warping could also result.

A number of years ago, I purchased a museum-grade piece of Mexican cocobolo.  It cost me $1000.  I split it down the middle in order to get a pair of mirror image pieces for the front baffles of a pair of HT3's.  The speakers were stunning when finished.  Six months later, I had to throw the cabinets way.  The front baffles split and warped so badly, that they actually ripped the underlying MDF cabinet apart.  I was really happy I had not sold this pair to a customer.

If you do use hardwood for a speaker cabinet, there are a couple of things you can do to minimize problems. 

First, select a wood that is relatively stable.  This would generally eliminate burls and woods with wild grain patterns or heavy figuring.  Straight grain and minimal figuring is much more stable.

Second, make sure the wood is well-seasoned.  The wood should be aged (air-dried) for a minimum of one year for each inch of thickness.  The moisture content should be under 6%.  Wood becomes more stable with age.

Use thinner wood panels and perhaps sandwich layers with grain running in opposite directions. I other words, make your own plywood.

Kerf the wood from behind so that only a very thin layer is completely intact.  Fill the kerfs with some inert material (like epoxy) that is stable.

But the best approach is to avoid solid wood all together.  If you don't, you are asking for problems.

- Jim

Shows what I know! Thanks for the detailed information! 

[ricardojoa]

Ok Jim, thanks for the informative post. Im gonna dump that idea!