hardwood for stereo speakers

[ciscokid]

I've always wanted to build a set of stereo speakers for my home. Lately, I've been building guitar amplifiers out of exotic hardwoods and they have been turning out nicely and sound very good. I just purchased a tower kit from Solen that includes all the drivers and crossovers. They give you plans for constructing the cabinets and, while most people use MDF, I have an urge to use solid wood. My question is - what can this hurt? Will I not get good sound? Would one particular wood suit better than another. Right now, I'm leaning towards either black walnut, cherry or canarywood. I can get all of this stuff in nice wide 4/4 planks.

[Harry72]

They use MDF because its stable and has good resonance absorption. If a solid hardwood enclosure happens to split or crack even though not visable to us will effect the speakers performance and being HW it will resonate(same reason they dont use steel)
Even top audiophile brands use MDF or composites. Your speakers still can look like solid hardwood, just get creative with veneering(make your own).

[SilentButDeadly]

There is no reason you can't make a speaker cabinet from real wood. However, if the cabinet design is a traditional box then it almost certainly won't sound as good as one made from MDF. Real timber just isn't as consisent in structure and sonically dead as MDF.

Possible exceptions to the general rule may apply with open baffle designs (eg. Linkwitz Orions) and single driver designs (eg EL Jordan) but in both cases you'd be best served by some seriously dense timber in high quality grades (no imperfections).

As Harry suggests, now might be a good time to learn about real wood veneering....which isn't as hard as it looks!!

[wixy]

From my understanding plywood provides a better sound than mdf.

[woodbe]

Many euro brands come with birch ply cabinets, and yes, they are apparently equal or better than mdf.

Unfortunately, birch ply is either unavailable or horribly expensive here. What we get is a lower density ply and even then you have to be careful to get ply with little or no voids.

I have a speaker project in the wings, and I'm tempted to make two sets of cabinets using ply and mdf to see if there is a noticeable difference... I like the look of ply:



woodbe.

[woodbe]

By the way, that photo is not of any of my speakers. Here is the link:

http://www.vikash.info/audio/W3-871S/

woodbe.

[ciscokid]

Perhaps I should be more clear. I don't intend to simply make a hollow box and stuff drivers into it. The speakers I intend to build have a vast array of interior baffles and ports. My intentions are / were to build the outer panels out of solid hardwood, say between 19 and 25mm thick, and to do all the interior work out of MDF. What if I use a really heavy hardwood for the outer walls? Would the speakers be too boomy or too dead?
I've read up on using big sheets of veneer and even have a supplier, but hate the thought of investing in all that vacuum bag stuff for something I may not use again. I looked at my current speakers (a pair of Polk towers) and, yes, they are indeed veneer. Nicely done, but veneer just the same.

[woodbe]

Well, heavier the better

The ideal in the music reproduction business is to have as uncoloured sound as possible. Real wood is more subject to resonance than mdf, so it will likely introduce some coloration that wouldn't be there in a mdf version of the same speakerbox. That said, it may still sound great.

What speakers are you building? it sounds like some sort of transmission line design? I've only ever made simple boxes with drivers stuffed into them, and they sound pretty good The magic is in the details, and the matching of driver to enclosure...

Regards,

woodbe.

[stolar]

instead of building a box with a thick heavy solid timber walls, use the thin flimsy stuff and build duble wall outer shell. Then fill the space (within the double wall) with sand or find lead shot.
that will be as dead as a dodo! no resonance ! you don't really need bracing either!
tou could use the sold timber on the outside and mdf on the inside of the double walls. As long as the internal construction is well sealed you don't really care about possible cracks in the the sold timber.

just a thought anyway !

[wixy]

Unfortunately, birch ply is either unavailable or horribly expensive here. What we get is a lower density ply and even then you have to be careful to get ply with little or no voids.

Newbie question, how do you tell if the ply has voids in it? Always looks pretty solid to me.

[soundman]

How do you tell if ply has voids?
Just by looking at it you cant be sure.
Selecting the grade is the best you can do.

Marine ply has no voids... thats part of the spec.... structural CD will almost certailny have a few voids... the spec allows knots and cracka and such in all but the good face.

I strongly believe that MDF will in almost all cases be less resonant and more consistent than ply. However good ply will be far more durable. Thats why good pro audio boxes are made of ply... oh and they are lighter.

the main problem with solid timber is dimensional stability. Just look at a good article of building tables and you will see the problems in keeping a flat table top flat and not splitting.

in building a speaker box you have a complete box.... somewhere there will be crossgrain working against long grain. it will be almost impossible to stop the joints busting each other appart.

my recommendation is this.
If you want to use solid timber and have a good design.
build the operational parts of the speaker box..... the box its self from good ply or MDF then furnish it with timber panels or plates..... or get artistic and build in a support structure, base and other trendy stuff from solid timber.
you get the stability and ease of working in mdf, you get the looks of timber AND it should all work because the two parts are in effect independent.

cheers

[SawDustSniffer]

when a speaker moves it produces + sound infront of the speaker and - sound from the back of the speaker , a good speaker box would totally obsorb the sound from the back of the speaker with no restiction of the movement of the speaker

the best place for a speaker is through a hole in a sound prof wall ,the negitve sound radiates from the back and there is no restiction in the movement of the speaker ( no box )

in a box you can use blow holes to stop the restriction but sound from the back of the speaker gets out , so baffels are added

the best sounding speakers i made were jarra venered /solid bull nosed eadge strips over 20mm thick CFC ( compersed fiber cement sheet ) bathroom flooring off cuts, epoxied together, with 3 baffel plates and blow hole in the back for each of the 6 speakers ( seperate boxes ) ,all internal surface's were covered in R2.5 " Rock Wool" cieling insulation

thay were so heavy i put wheels under them
my brother sill has them , i went traveling away from Adelaide and he was happy to store them ( and use them ) 12 years later he recons " Posetion is 9/10th's of the law "

also made a mate a set out of off cuts of 6mm CFC ply
face layer full sheet
2nd layer 25mm wide stips running vetical 50mm apart
3rd layer 25mm wide strips running horizontal 50mm apart
4th verical between the 2nd layer positions
5th horizontal between the 3rd layers postion
6th layer full sheet
the blow holes through the hollow ply

never thought of filling the gaps with tumbled sand ( beach sand ) sharp sand ( brickys sand) will compact

[SilentButDeadly]

Many euro brands come with birch ply cabinets, and yes, they are apparently equal or better than mdf.

Unfortunately, birch ply is either unavailable or horribly expensive here. What we get is a lower density ply and even then you have to be careful to get ply with little or no voids.

I have a speaker project in the wings, and I'm tempted to make two sets of cabinets using ply and mdf to see if there is a noticeable difference... I like the look of ply

Try the marine grade hoop pine ply from Austral. It is an AA grade product and therefore has nil core gaps

http://www.australply.com.au/pr_marine.html

The other alternative is the pre-veneered MDF. Birch and Jarrah finishes are avilable

Both are available in the eastern States from Mister Ply & Wood. However, you may have to wait awhile for your order to be filled for hoop pine.........

[soundman]

when a speaker moves it produces + sound infront of the speaker and - sound from the back of the speaker , a good speaker box would totally obsorb the sound from the back of the speaker with no restiction of the movement of the speaker

the best place for a speaker is through a hole in a sound prof wall ,the negitve sound radiates from the back and there is no restiction in the movement of the speaker ( no box )

in a box you can use blow holes to stop the restriction but sound from the back of the speaker gets out , so baffels are added

The above is not .. exactly true.
if you mount a speaker in an infinite bafle what you will get is the fundamental performance (more or less) of the speaker drive unit.... warts and all..... you will still have a resonant peak as per the chatacteristics of the driver and the driver will be completely undamped apart from the damping provided by the source impedance of the power amp.

a properly designed speaker enclosure will not (in most cases) absorb all of the rearward energy of the speaker..... it will infact provide a complex physical system of damping and loading that controlls and balances the speakers basic properties.
In some cases it will redirect and process the rear energy and use it to create more output and or extend bass response.

The holes in the typical ported speaker are in fact (in conjunction with the whole box system) very complex filter systems. They will (properly designed or not) have certain resonant properties that change the response of the box system and reprocess the resonant energy of the driver.
In physics.... some of the time the hole will "appear" to be blocked, some of the time the hole will be a significant source of bass frequencies, at other times the port may pass air thus controlling the response of the bass driver.
The "hole/s" or ports in a prpoerly designed speaker design are a very.. very complicated little system and the maths is just beyond all but the most serious maths/science gurus.
the rest of us use computer simulation.

And thats without getting involved in the issues of "taste" and "philisophy".

It has been my experience that there is a lot of discussion about esoteric issues in HIFI but many fail to deal with the simple basics of building a properly concieved design, using good workmanship and appropriate materials.

There is much discussion on the best sort of board..... the americans and the europeans will get very one eyed about using birch ply.... yep birch is very nice... buy thats what the yanks and the euros make their good ply out of.

Three reasons birch is good.... it is heavy, significantly heavier than pine or luan.....it dosn't seem to have the big knots that most pine has so voids are less of an issue.....it is close grained and finishes realy well even on the edge grain.

In this country all out birch is imported and is reasonably expensive..... certainly more expensive that in the country of origin.
But we doo have some very good ply here too..BB hoop is great stuff and not that expensive.... its spec'ed as BB but the cores are prety damn clear of voids..... as I said before marine should not have any voids and should be all "B" veneers.
The luan that comes here from Asia is not as heavy as others but is prety stable and prety damn good as far as voids.
Then you start going up market
Norply.. do some all ausie hardwood ply... you want heavy!

Actually I don't cop the "Voids thing" as being the issue that its made out to be... unless you are working in lower grades of ply any voids will be small and...... sorry you won't find them by banging the sheet with a ballpien hammer.
You would have to be very lean on with your ply thickness for it to be a problem.

you need to think when you are building speaker boxes.
I have seeen and heard of all sorts of "methods" to make the "box more rigid / dead".
Most of these things are a PITA.
Appropriate materials, adequate bracing and proper construction methods will always achieve results where just going for weight sledge hammer engineering.

I have never seen a respected commercialy produced studio monitor with sand in it or cement blocks or cement sheet or any of the dosens of crackkpot things that " enthusiasts" enjoy fiddling with.

keep it real fellas.
cheers

[SilentButDeadly]

The only problem with Norply is that it is no more. The factory in Kyogle burned down in November 2005 and the shareholders voted earler this year to wind it up...