Hi all!
I'm new to this group, but I hope you can give me some pointers for my next build.
I am building a set of "furniture grade" speakers for my Father-in-law. I have settled on a Vifa 6.5" P17WJ-00 coupled with a Dayton RS28AS-4 in a 2way design. From the simple tools I have used, this should make a nice match crossed at 3.2khz, but here's the question:
I am going to use solid red oak (not veneered) for the speaker construction. The oak is 1" thick. Dimensions will be 16 x 10 x 6.25. Is there anything special I need to consider when using this material? This will be the first build using red oak; all my others have been 3/4" MDF with really good results IMHO. I typically wouldn't go to this expense of using solid oak, but, the wife wants these to "mean something" and the father-in-laws house is all trimmed in red oak. Not to mention his current speakers are Advents from 1973 - so I expect he'll keep them a while.
Any thoughts / comments before I begin my build this weekend?
Thanks much!
I'm new to this group, but I hope you can give me some pointers for my next build.
I am building a set of "furniture grade" speakers for my Father-in-law. I have settled on a Vifa 6.5" P17WJ-00 coupled with a Dayton RS28AS-4 in a 2way design. From the simple tools I have used, this should make a nice match crossed at 3.2khz, but here's the question:
I am going to use solid red oak (not veneered) for the speaker construction. The oak is 1" thick. Dimensions will be 16 x 10 x 6.25. Is there anything special I need to consider when using this material? This will be the first build using red oak; all my others have been 3/4" MDF with really good results IMHO. I typically wouldn't go to this expense of using solid oak, but, the wife wants these to "mean something" and the father-in-laws house is all trimmed in red oak. Not to mention his current speakers are Advents from 1973 - so I expect he'll keep them a while.
Any thoughts / comments before I begin my build this weekend?
Thanks much!
Some hardwoods can be very resonant, so perhaps make them a little larger to allow for some extra damping materials inside. Your other option is MDF with a nice veneer, which would probably be sonically much better and you won't have the risk of cracking which is a very real possibility with hardwoods.
I've been seriously into woodworking for over 15 years. This is the only place I hear people talking about solid wood cracking. Building boxes or anything else out of hardwood should not cause cracking. I have seen one example of a speaker that cracked. While I don't know the details I'm sure that it is easily explained.
Outside of the DIY speaker builders, I have not heard of other wood workers that have their project crack because they use solid wood. FWIW, my father has been woodworking for 40 years, my grandpa about the same, and I am involved in a wood workers association, so I am exposed to many different projects and designs.
What I can't understand is why everyone in speaker building thinks a box made of solid wood will always crack.
My only advice in using red oak is that you need to be careful with the joints. Unlike mdf, you don't get to "cover up" any of your mistakes with veneer or paint.
Outside of the DIY speaker builders, I have not heard of other wood workers that have their project crack because they use solid wood. FWIW, my father has been woodworking for 40 years, my grandpa about the same, and I am involved in a wood workers association, so I am exposed to many different projects and designs.
What I can't understand is why everyone in speaker building thinks a box made of solid wood will always crack.
My only advice in using red oak is that you need to be careful with the joints. Unlike mdf, you don't get to "cover up" any of your mistakes with veneer or paint.
s7horton said:
Hi,
It's not that it will crack, it's that it may crack.
Being a serious woodworker, you have no doubt heard of cross-grain gluing? Furniture projects generally don't need to be sealed, leak proof boxes.
Another point- as solid wood wil expand and contract due to moisture level, it can place a lot of stress on the basket of a large driver, and the fasteners used to attach it.
I would advise against using Solid wood. If you live in a temparate climate of any kind there will be expansion and contraction of around 3% across the grain. When the solid Oak changes size something has to give and it is usally not the glue joint, it the wood itself. Thus you get cracking. This is the reason why they came up with plywood, Each layer is criss-crossed the other direction keeping the wood stable and from changing size. Wood really only expands width wise not length wise( it does but only 10ths of a %"). Thus the reason for plywood. I'm not saying you can't use hard wood, but if you don't live in the desert It will crack someday.
one more question
Thanks all for the advice - I really appreciate it. I'm lucky enough to have a friend who works at a large specialty furniture shop here in Denver, so I have access to all his super cool wood working tools, so this should be a quality build. A six pack goes a long way!
I plan on biscuit joining all sides and gluing as well. I understand the possibility of cracking, I'll just have to tell my father-in-law to make sure he keeps them oiled (wife is set on the oak....)
As far as undesirable resonance - should I fully stuff these bookshelf speakers to help compensate for the density of the oak? Any other internal damping materials to look at?
Thanks again!
Thanks all for the advice - I really appreciate it. I'm lucky enough to have a friend who works at a large specialty furniture shop here in Denver, so I have access to all his super cool wood working tools, so this should be a quality build. A six pack goes a long way!
I plan on biscuit joining all sides and gluing as well. I understand the possibility of cracking, I'll just have to tell my father-in-law to make sure he keeps them oiled (wife is set on the oak....)
As far as undesirable resonance - should I fully stuff these bookshelf speakers to help compensate for the density of the oak? Any other internal damping materials to look at?
Thanks again!
Although I have only used this method for amplifier construction, you may want to consider a "2-ply" type arrangement. Whereby I made the case from plywood with a 4mm wooden face glued to the plywood so that it becomes one "plank" I used 45 degree mitres to join em at corners and am still most impressed by it.
I hate regular veneers, they are just not durable enough, and the moment a corner is scuffed the illusion is broken. That is why I use this method.... well, mostly becasue i'm too cheap to just buy wood generaly...
But it does give you the expansion resistance of the plywood, with the beauty of solid-wood... Last time I used cedar wood, which is so hard you can get a gloss finish useing 400 grit sandpaper. Realy glad I didn't have to work with thicker pieces.
I received a fresh 2x1m sheet of 4mm thick cherrywood from a friend, two weeks ago, can't wait to think of a project to use them in.
I hate regular veneers, they are just not durable enough, and the moment a corner is scuffed the illusion is broken. That is why I use this method.... well, mostly becasue i'm too cheap to just buy wood generaly...
But it does give you the expansion resistance of the plywood, with the beauty of solid-wood... Last time I used cedar wood, which is so hard you can get a gloss finish useing 400 grit sandpaper. Realy glad I didn't have to work with thicker pieces.
I received a fresh 2x1m sheet of 4mm thick cherrywood from a friend, two weeks ago, can't wait to think of a project to use them in.
MJL21193 said:
Not many here are building sealed boxes. Most are ported or vented.
Tall drawers have been made of solid wood for many years without any cracking whatsoever.
Speaker builders are not the first ones to try and mechanically fasten something to hardwood. Many different hardwood items have associated hardware that may or may not be the size of a woofer. The better the finish, the less expansion/concraction is involved. If you finish the piece 100%, the likely hood of moisture getting to the piece is small.
Look closely at a "Tall drawers ". What you will see is the back floats. You will see that the top is not attached with glue, but some mechanical fasteners with some float. The Side panels are made with the main panel floating in a frame.
All in all, you will see several very sophisticated mechanisms used so that the chest can be "solid". The point is that none of these techniques are appropriate for a speaker box.
Doug
Edited to add Double Negative
Edited to remove Double Negative
One compromise you might consider would be to add a 1/4" layer of HDF or "masonite" glued to the back side of the oak. This will make it harder for the oak to expand and crack and also provide some resonance reduction. I would also brace the cabinet well with shelf or window bracing, rather than just stuffing it.
BTW, I've done a number of speakers that are hardwood glued over mdf and never had anything crack yet. That's how these were done, cherry and maple over mdf.
Good luck.
BTW, I've done a number of speakers that are hardwood glued over mdf and never had anything crack yet. That's how these were done, cherry and maple over mdf.
Good luck.
MJL21193 said:
Will you please get off of your high horse? I know enough about woodworking to know that gluing cross grain is not universally considered a bad idea commercially, and that some commercial products use this technique. True they carefully match moisture content, design for lots of glue surface, and use the appropriate modern glue. Don't bother baiting me, I am just so tired of watching you drown out the opinions of other knowledgable woodworkers by your tireless spamming.
To help alleviate possible problems, here is what I would do.
Make the sides and top as a unit, use an MDF back and sub-front tucked inside.
Then attach the main baffle from behind, through rubber grommetted holes in the sub baffle, with a thin layer of rubber foam between the baffle and sub baffle.
The problem with a fully solid timber box is that the shrinking and expanding of the baffle puts a very large stresses on all your joints to the main box, hence also within the baffle itself.
The method described above will float the baffle, allowing small movements of the baffle without straining the rest of the structure. The rubber layer also stops any resonance in the baffle
Make sure the cabinet itself is also well braced at irregular intervals to reduce and spread resonances in the sides and top.
Make the sides and top as a unit, use an MDF back and sub-front tucked inside.
Then attach the main baffle from behind, through rubber grommetted holes in the sub baffle, with a thin layer of rubber foam between the baffle and sub baffle.
The problem with a fully solid timber box is that the shrinking and expanding of the baffle puts a very large stresses on all your joints to the main box, hence also within the baffle itself.
The method described above will float the baffle, allowing small movements of the baffle without straining the rest of the structure. The rubber layer also stops any resonance in the baffle
Make sure the cabinet itself is also well braced at irregular intervals to reduce and spread resonances in the sides and top.
btw, "all real timber" speakers are possible, you just have to make sure you take problems of differential shrinkage etc into account, rather than just crossing you fingers and hoping !!
http://members.optusnet.com.au/~gradds55/sauron2.jpg
(they have proper feet on them now )
http://members.optusnet.com.au/~gradds55/sauron2.jpg
(they have proper feet on them now )
leadbelly said:
It's not the glue joint that fails, it's the timber. And as for moisture selecting your timber, that only works if the piece is kept in controlled humidity conditions, such as a permanently air-conditioned office building.
I have successfully used a similar idea to Andy's before now, only I fixed the front baffle on with centrally mounted biscuits, leaving the outer edges to float.
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