use of wood as enclosure

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Ok I have read about how mounting your pcb's to certain kinds of wood coated in certain kinds of resins sounds better than your typical metal enclosure. Im curious about this, and if anyone has any experience.

First some questions, what kind of woods are usually used for this? What kind of Resins or finishes are used. I read that they used natural resin coatings made from wood resins. They also mentioned that this stuff was the same as is used on violins and such. Where can I get such resin finishes, or do I need to make this stuff myself?

Now finally, for my specific application. I just finished two different headphone amps, and I want to try mounting them into a wooden enclosure, like Grado does. Both are designed for portable use and run on two 9v batteries. One is commonly put into mint tins, the other is really too large, but still pretty portable. Both are biased into class A operation, and sound quite sweet, I must say. As far as what I can do on my own, I have access to a wood shop with a router, saws, etc. However we dont have any real unusual tools. I was thinking I could get a block of something, say mahogany, route out the inside of the block, and mount it that way. However, this isnt the most precise, and I dont expect the results to be great. Anyone have any ideas that might make this better. Another Idea I had was a clam shell sort of case, routing out the inside of two small blocks, and then screwing them together, making it a complete case.

Thanks for any ideas or clues here. Im probably being silly to put such amps into a wooden enclosure, but Im looking for something different. Thanks for any help.
 
Try a Google search for tonewoods. I'm hard pressed to state what a reason might be for a circuit to sound 'better' mounted to a certain wood, but I do it myself.

(My reason is more pragmatic: I have a lot of woodworking tools, and next to no metalworking tools.)
 
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Joined 2002
Two things to bear in mind with wood enclosures. Heat and EM screening. Wood can't really cope with either of those things on it's own. But if you can work round those problems, then the world is your oyster, and there is nothing better than a fine piece of wood. As for exotic finishes that change the sound, I am sceptical, but hey, if you have the money to spare, give it a go.

As for techniques, for the small amount of wood you would be using, you can afford to make a few trials, and see what works best.
 
I have to be honost, I am extremely skeptical of how wood could effect the sound, I could only give wild guesses. I first became intrested when I read the C37 laquer deal. I read all these people trying it and using it, thinking, thats insane, how could it possibly effect sound, even slightly. I have no idea if it does, Im not about to spend that kind of money on a little tincture of the stuff. From there I found a sight where I guy built a gainclone like amp, mounted it to a piece of wood coated in natural resin based laquer, and found the sound of it to be better. He sell's these as completed amps, and listed a studio and Cabasse speakers as two companies who are clients of his for these amps.

I have been building most of my amps onto wooden bases for the same reason another member mentioned, I dont have many power tools to use to cut aluminum. I also have lots of wood around, and not much metal. I was always pleasantly suprised by the sound of these cheasy little amp's, but at the same time, I never would have associated mounting them onto wood as having anything to do with it. I have a GC in the works along with these two headphone amps, and I wanted something attractive to mount them in. I had read about the tone of wood with electronics, and thought I would give it a shot. I have some Koa, Bubinga, and Curly maple blocks sitting around, which are too small for anything else, that might work perfectly for these projects. I was just curious if anyone had more experience with it here. Also, I know that wood offers no RFI or EMI shielding of any sort. Its funny too, cuz I use shielded wire inside my amps often, yet will have them mounted in such a way that they are completely unsheilded. Anyway, I seem to live in an area that is without radiation, as I hardly ever pick anything up. At worst I sometimes pick up trucker radio waves, and I have to say, mostly on cheaper components like my computer speakers, and no so much on my main stereo.

On this site, which I have refrenced a few times, the guy mentions his experience with wood effecting tone. He mentiones its effect it has on guitars. This is an old trick for anyone who has played guitar. Though I hate the idea of stripping the finish from a guitar usually, specially cuz most people dont refinish them propperly, I have done it to three of my guitars. I have a Gibson ES-135, a Chandler Telepathic 57', and a Martin acoustic. All of these came with standard laguer finishes, and all of them I became tired of. I wore the finish off the neck of my Marten and Chandler, so I decided that I didnt like the slick finish anyway. I sanded off the finish on both guitars and then cleaned the wood best I could. I then refinished it with a violin laquer I got from a local violin maker. He makes it himself, and is unfortunatly now gone, so I have no more source for the stuff. I later cracked the finish on the Gibson at a gig and had the finish taken off by gibson. I then refinished that one with the same laquer. I have to say, every single guitar now sounds warmer, richer, and has longer sustain. To me, this is sensible given that we are talking about an instrument in which the actual wood of the instrument plays a role in the sound, by design. We also have comparably larger vibrations because of the strings, which could resonate wood more effectivly. By that same token, Im guessing, that the oscillations and slight minute vibrations which take place in a cuircit could potentially transfer into and resonate the metal enclosure. Same could happen in revers, enviromental vibrations return back through the enclosure into the board. People do use spikes and cones, and hear differences. They feel that thicker stronger, better dampened cases effect sound. They also feel that adding dampening material can effect sound. By this same token, I suppose that you could simply embrace these resonations and use ones that are more musical, such as those in wood. Like I said, this is simply a guess as to why it might effect the sound for the better, or at all.
 
Try this little test with one of your amps:

Play some very sublte music, where you can hear every detail. While it is playing, have someone tap on the amplifier, gently but firmly, so you don;t hear the impact directly. Most importantly, do this while you cannot see them. Perhaps put the amp in a different room than your speakers.

Can you hear the tapping sound coming through your speakers?

Perhaps you could with a tube amp, as they are very suseptible to "microphonics" where the internal structure of the tube vibrates, but there is no such free-standing structure in a transistor. With tubes, you want to keep the structure from resonating at all, not enhance the vibration. Much like a speaker cabinet, you want it to be dead to vibration (high-mass, lower resonant frequency). I think if anything you would want the same in an amplifier suseptable to vibration.

Comapring it to a guitar is liek apples and oranges. A guitar body is supposed to vibrate. That IS the amplifier for a guitar. (I must say, it was nice reading your post. Very well wriiten. Made me think about why I love woodworking.)

Let us know what you find.

My point it, if large scale vibration doesn't impact the sound, then these chassis resonances probably won't either. Also, I think if solid-state amps were so suseptible to vibration, pro-PA amps would not last nearly as long as they do.

Just my 2cents (why don;t keyboards have cent symbols on them?)

-b
 
Like I had said before in my post, it was a wild guess. I do not believe that it could have that effect, but I figured I would make a guess, based on what I had been reading. I do agree though, wood working is something special. There is a gross pleasure I take in watching a piece of raw lumber become a thing of beuty as you sand and polish the piece, apply coat after coat of finish. Not to sound too strange, but I really do find something sexy about a fine piece of wood propperly finished.

I figure at this point, I will give it a shot, if I hear a difference, cool, if not, so I have a pretty little amp enclosure. So I found a few things out about this. First thing I found was that Stradaverei(Sp?) were not finished as his said but rather finished with something known as a French Polish. After the fall of the French Polish and oil finishes people began using nitrocellulose, which is the natural wood fiber finish. However they would finish it off with shellac I guess. Today instruments are finished with either a nitrocellulose or water based varnish. Unless of course they are one of the many instruments finished in a cheap finish, inwhich case its probably polymer based. I am buying a quart of the french polish stuff for 12 bucks. If nothing else, I will have a nice finish to use on stuff.
 
I stepped up from regular cinch plugs and chassis parts to versions with Teflon isolation, stepped up from regular cable to ones with Teflon.
After that i tried to find a way of attaching copper clad to Teflon boards, at the time that Teflon pcb's were solely used in the aerospace industry.
(think of how to have something stick on a material used for non-stick pots and pans).
I grew up with rolls of Teflon foil in DuPont boxes in my dads plant, it did not surprise me that Teflon is still adding advantages in many fields.

Now, Teflon isolated plugs, cables and pcb boards are standard, regarded as having a positive influence on sound.
Microphonics influence sound, several amplifiers have been built with pcb's mounted with dampeners.
For tubes different material damping slide-over rings are sold, even in wood, with prooven results.
Some have built amplifiers using wooden boards, with wire wrap or direct soldering techniques.
There is one famous guy in Germany who has been building turntable arms of wood for a long time.

Given that wood has been the best acoustic material for a very long time, who is to say it may not have a positive effect on sound when used for amplifier casings.
Like with a lot of other applications it may be that a combination of various materials, including wood, may lead to better results.
I am still often amazed about the physical properties of wood.
Much of the woodwork in my 1935 house that i am renovating is still as good as new, some wooden furniture have survived ages. I built a sailing boat in wood with fiber roving reinforced epoxy lamination. It is an easy building material, longlasting, light and outperforms most others.
With violin building the kind of lacquer on the violin has a tremendous effect on its sonic signature, i do not recall anyone ever examining effect of lacquers or resins on amplifier sound.
Known however are the fools who wrote on CD's with different marker pens supposing it influenced CD sound.
Turned out they were not such fools. These marker pens have been professionally marketed now for years, even CD washers.
I am sure not going to spend my time coloring CD's but i respect the ones that do.

On top of that wood looks good, i was impressed by Italian wooden amplifier design in the 90's.
I do not agree that microphonics only apply to tube amplifiers, it has an effect on solid state too, and has been proven.
The effect is a lot less, and each needs to decide whether its worth the bother.

I dont bother, for the same reason that i do not spend time and money on cable stuff.
But i am a metal guy, i love to build heavy casings that shine and look like Fort Knox.
Visually the things you can do with wood are unlimited compared to metal. Making a casing out of a solid piece of wood with routed openings for the right kind of alloy heatsinks sounds great.
For the kind of wood you might check with wood types used for audio stands, a lot of research has gone into that.
 
Sorry for going off topic. But I have been thinking about asking this, which I'm sure has been done here before. I just came up empty (rather lots of unhelpful hits) when doing a search. So instead of creating a new thread on an old subject... Not to mention that I'm currently on a posting rampage.

My question is, what are the pros and cons of using aluminium compared to stainless steel, or vice versa? I guess I talk shielding and magnetism in particular.

I personally prefer wood, by the way. But it's hard to get away from metal.
 
French Polish Post #11
quote:
[Stradivarius vilons were] not finished as his said but rather finished with something known as a French Polish.


French Polishing is basically a method for applying shellac using a bit of oil as a pad lubricant. I'm surprised to read that. I had always assumed violins were varnished only.

About 10 years ago a Scientific American article reported that somone in Utah had finally figured out what made a Strad a Strad. The wood (befor or after shaping? - I don't recall) was immersed for an estended period in salt brine, most like just lagoon water in Venice. The effect (letws hope my memory gets this right) was that the porous fibers pinceh closed at the ends and remained closed even after the wood dried, thus forming zillion of resonant chanbers. The author who was both a musician, woodworking hobbiest and chemist had been building violins for years but was not satisfied with the results. After adopting the brine imersiuon treatment of the wood he built some pieces and had them evaluated by some proffesional symphonic musicians who opined that they were spot on.
 
phn said:
My question is, what are the pros and cons of using aluminium compared to stainless steel, or vice versa? I guess I talk shielding and magnetism in particular.

This has been discussed on another thread.

Alloy is non-magnetic but steel(or stainless) will give better shielding. The best being MU metal.
Stainless steel is very expensive to work with, scratching will take hours of polishing, for production that is a major factor.
The major decision for alloy as enclosure material is the weight and that it is an easy construction material.

I built housings in chromed 6 mm steel plating and stainless steel. You tell me how you will get steel plating with undamaged straight edges. Drilling and chamfering holes in alloy is easy.
Most fancy amplifiers are built of alloy plating, grinded and anodised.That is the easiest way of doing it in metal, ironically most find that to be so good looking.
In my view thick steel casings are better, even better with a layer of copper on the inside.
I like to build split level amplifiers, with a metal separation of powersupplies to give maximum shielding. Toroidal transformers i put in pans and seal in thermal epoxy resin. For preamps and a cd filter/amp i used MU foil a couple of times.
Metal is nice if you are building high frequency amplifiers.
I built a 1 MHZ power amplifier, i was told that i would do well shielding it like its done for radio frequencies.

Downside of steel encasings is the added weight. If you build big meaty amplifiers you will be surprised even more by the pound number when steel is used.
 
Hey Sam9, and everyone else for that matter, I agree in much of what has been said. I also read about the brine immulsion. This is done as a sort of wood sealer/hardener. It would only be done on porous hardwoods. I didnt mention it cuz I was planning on making mine out of maple first, which would not need it. Today other methods besides brine are used to harden the wood and close up its pores, but I'm sure the brine method has its own sound. I still would argue that the finish has a lot to do with the sound also, the use of natural shellacs and varnishes. If you cured wood with the brine, and then coated it in polyurathane, I bet it wouldnt sound like a Strad.

As for the comment about using French Polishing, I am aware of what it is, and was also suprised when I read that. I read it on more than one sight, but I will say, I could have that wrong. The sights said that companies switched to varnish later on, but used Shellac for 100's of years. You will have to excuse this, I am only 23 after all, but I laughed for a while when I read that it was applied with a soft tampon. I did not realize that word was used for anything other than what we know its for today.
 
This has been discussed on another thread.

Alloy is non-magnetic but steel(or stainless) will give better shielding. The best being MU metal.
Stainless steel is very expensive to work with, scratching will take hours of polishing, for production that is a major factor.
The major decision for alloy as enclosure material is the weight and that it is an easy construction material.

Regarding steel enclosures: On a couple of ocassions I have bought (or just walked off with) an obsolete router, switch of other piece of communication gear that was about to be thrown out and ripped the insides out to use as an amplifier enclosure. The structural qualify is typically very good. If you want a nice high-end audio look you just bolt a thick sheet of brushed aluminum on the front.

I have no woodworking skills, but if I did, I would use a basic metal enclusure that I could slide into a nice exterio wood exterior. I'm sure a way could be worked out to provide for ventillation or maybe just expose the heatsink fins externally on the sides.
 
WorkingAtHome said:
I just heard about this "wood affecting the sound" business. I have to say that it is one of the single most rediculous things I have ever heard.

In my opinion, the single most ridiculous thing is "know it all" posters who make blanket statements without having any experience whatsoever with the topic at hand.

Using wood instead of metal will absolutely make a difference in the sonic performance of an electronic component. (And no, I'm not talking about hum pickup or anything so obvious.) The difficulty comes in determining which material gives the best sound, not whether they sound different.
 
The responses seem to be getting more open minded, Im glad to see that.

You know I think one of the big reasons that people become so turned off is because of products like wooden volume knobs. I dont necassarily doupt its effect on sound, but I'm sure its not worth what they are charging for it. Same goes for many of the various tweeks I have seen. It bugs me when I see turned maple cones, or maple speaker stands, or component stands, or whatever. I specificly mention maple because, as far as hardwoods go, its cheap and readily available. We arent talking about some rare rainforest wood that has to be shipped over in small quantities. Maple trees are almost the only tree's sitting in my yard, and next to pine trees are probably the most common tree in New York State. It kills me to see what they get for things made out of maple. I really do think that is what throws people off and closes there minds. Same goes with wall outllets. I dont deny what they can do, but it does seem insane to charge 50 dollars or 100 dollars, or even more, for a nickel plated hubbel outlet with some special "Audiophile" treatments. At the same time, I did change all the outlets in my stereo room with Hubbel outlets. I figure that if nothing else, they make a far more secure connection. I also now have dedicated electrical lines, anyone who is gonna try and argue that this doesnt make a difference, I can show you, I can put everything on one line, and then seperate it out to my three different lines, I guarantee you will hear a difference.

None the less, the point of this post was not to praise or attack audiophile tweaks. There are people who believe that all amps sound the same, all components sound the same, all wires sound the same, etc. I am not of that camp, and firmly believe that such things do sound quite different. I would like to experiment and see what effects wood might have on electronics by making some enclosures out of wood for my amps and preamps.

I would like to know if anyone has any links or sources for further reading on the effects that an enclosure can have on electronics. I have read reviews of many products placed in various box materials because it improves sound. I recall an amp in Stereophile with an acrylic top which was said to let all the radiation out of the box, thus improving sound. Have no idea if it worked, but I know they loved the amp. I have to imagine that someone has written something about this effect and other issue with an enclosure. I had heard also that aluminum was often preffered to steel because it was better dampened than steel. I have no clue if its true, but I would suspect that if this is true, vibrations are something that some designers are concerned with.
 
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