hardwood for stereo speakers [Archive]

soundman

15th December 2006, 02:02 PM

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

18th December 2006, 01:16 AM

SilentButDeadly

18th December 2006, 11:22 AM

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/gfx/coregap_mar.jpg
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

18th December 2006, 01:01 PM

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

18th December 2006, 03:44 PM

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...

greenie512

18th December 2006, 05:42 PM

Can’t resist this, basically I would agree with Soundman. Remember hardwood is exactly that – hard – hit it with a hammer and it’ll resonate at a certain frequency. So along with stability issues you will find a hardwood cabinet will “add” its own overall sound/characteristic to such a system.

Now I recently read somewhere (dam sort term memory) that from the overall sound of a system 20% can be generated by cabinet resonance – now that seems a large number to me, so I’m not prepared to argue about that but I can imagine that a poorly built cabinet of the wrong material could add (and degrade) the overall sound of the system.

As suggested built boxes of good quality ply or mdf and mount your hardwood on the surface by one method or another to allow h/w to expand/contract naturally.

stolar

18th December 2006, 08:17 PM

snip, snip ...

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

Could not agree more with you that the most important factor is quality of workmanship and choice of appropriate materials. Nothing can make up for failure in either of the two.

I also absolutelly agree that one shoudl keep it sensible but disagree with the implication that the esoteric designs are bad because they are not comercially available or do not appear in profesional use. Comercial and in particular profesional designs are constrained by cost and manufacturing process and are mostly produced to "good enough for the target market" level of audio quality. Comercial designs deneraly do not produce audibly better results then esoteric designs. Profesional equipment generaly, as a rule of thumb, produce audilby inferior results to the equaly priced audiofile equipment. On the other hand profesional equipment will withstand rigors of constant use without failing.

Admitedly not all ezoteric designs will produce audibly better results, particularly if they rely on design and neglect the first two factors (workmanship and material).
Most ezoteric designs are only an attempt to improve (in a small increment i might add) on the already well known and accepted principles of speaker box building and as such are not bad in priciple. Some are misguided and some are waste of effort. Some will produce audibly better results and some will not.

One thing to keep in mind also is that most traditional studio monitors were designed as "near field" monitors which does not make them ideal choice for decent size living room.

The beauty of a "home baked" speaker system is that that you can encompass all the known and accepted principles of good box design without care about being sensible or comercially viable.

Harry72

19th December 2006, 01:59 AM

"Admitedly not all ezoteric designs will produce audibly better results, particularly if they rely on design and neglect the first two factors (workmanship and material).
Most ezoteric designs are only an attempt to improve (in a small increment i might add) on the already well known and accepted principles of speaker box building and as such are not bad in priciple. Some are misguided and some are waste of effort. Some will produce audibly better results and some will not."

True words... like most things, once you get to a certain point an extra 1000% effort may only get you a .1% increase.

IMHO I get annoyed with a lot of the misinformation audiophile crap on the internut its pedantic procrastinating BS, a newbie gets so confused by this they just give up because these people make it sound all so hard to do.

Its not hard to make a accurate solid box with some sensible bracing, any more than that your gaining very little... you only got to move that speaker 2cm in its room postition and the sound can vary wildly more than that extra 1000% of effort!

Its easy to start with a sensible design using reasonable quality speakers and xovers, there are some very good designs to be had for free if you look, us being WW'ers a set of speakers are a very good project... we'd probably be able to make and dress the boxes better than 99% of these pedantic procrastinating BS'ers.

soundman

19th December 2006, 11:47 AM

I do not wish to infer that esoteric design is not a valid or worthy persuit.
However the word of HIFI is to a large portion populated by types who look to strange and esoteric reasons and solutions first rather than dealing with the simple basics first.

I disagree that traditional studio monitors are designed for near field unless you also consider a large lounge room near field also.

Traditionaly monitors were placed at least 2 to 3 metres away from the operators position... hell 15 years ago a decent recording console was 5 feet from armrest to connector panel and 9 feet wide at least.... in recent times however controll rooms have become a lot smaller and yess many monitors are now designed as near field.

If 20% of your speakers sound is from panel resonance, the materials and construction methods must be pretty damn poor.

Norply gone...:( :( bugger, they made some nice stuff. their Structrual CD was close to being BC and had very few voids. Certaily good enough for rock & roll.

I've been reading, building speakers since I was a lad & have seen quite a bit of absolute rubbish touted in the name of better results.

There are a few out there who achieve very good results ( and usualy without foolishness) and have truly got good ears, the inteligence and knoweledge to know what they are doing.
But there are plenty out there who like to spiel on and fiddle about.... frankly lots of them simply don't understand basic physics and don't understand the difference between "different and better".

All you have to do is look at the long string of HIFI con's perpitrated over the years from directional copper cables, coloured markers for CD's and the latest "high end digital interconects for better clarity and warmth:confused: "

Soundman's HIFI reality check.
If you

Selected your speaker components carefully from a good manufacturer with reference to each other and your aims.

Used appropriate maths & physics, either manualy or from a computer sim to design your cabinet amd you understood the process. or you used a proven design.

Built your cabinet from appropriate materials, using good structrual methods.

Used adequiate and properly designed crossovers and good quality wiring.

Placed and supported your speakers properly in a good room

and

Connected your speakers to " decent" equipment using respectable cables of reasonable length.

Then you should start looking at "other things" to improve the situation.
Even then you should be looking for simple reasons why you aren't happy with the performance.

Sorry getting a bit religeous & carried away.

cheers

TassieKiwi

19th December 2006, 01:23 PM

Wo needs nancy-boy birch? This is plywood:

http://www.zeta.org.au/~kardon/Bridgewood.html

Resonate that! With 155mm H/W ply, you'll need good castors!

soundman

19th December 2006, 11:02 PM

I have actualy seen bridgewood.... seriously beefy stuff..... but it might have a few voids in it:D :D

A box made of 25mm ply or 32mm mdf dosn't have much resonance...... but that is getting borderline silly.

In the proportions of the domestic speaker now in vogue 18mm properly braced is pretty damn good.

cheers

Harry72

19th December 2006, 11:36 PM

Depends, if its a powerful sub you need thickness.
My sub is 36mm(18x2)thick and weighs a ton as its a 100ltr enclosure, still after 12mths since I last shifted it, its moved nearly 50mm from vibration!

soundman

19th December 2006, 11:45 PM

I have built quite a number of twin 15" 600 watt rms sub cabinets out of 15mm ply sleectivly braced. We have frequently stacked them 4 in a block and mid high boxes on top. They have a 3db down point at about 35Hz.
I can lift one on my own (just) very little vibration can be felt on the outside of the box running at full tilt and they don't seem to wander about.

For any speaker box rigidity is more important than weight.

cheers

woodbe

20th December 2006, 09:01 AM

For any speaker box rigidity is more important than weight.
cheers

Except... in the case of a down-firing subwoofer :)

My Brother has one of these, and on a polished floor, it needs to be anchored in heavy bass or it walks across the floor, and it's no lightweight.

soundman

20th December 2006, 10:23 PM

Except... in the case of a down-firing subwoofer :)

My Brother has one of these, and on a polished floor, it needs to be anchored in heavy bass or it walks across the floor, and it's no lightweight.

Exactly how much air mass do you think you are mooving?

I would be looking for other reasons why the "vibration" is causing the box to move.

My expectation is that the box itself is insufficiently rigid and/or mechanicaly damped.... thus it vibrates.....thus it walks.

If the box is sufficiently rigid and mechanicaly damped the only vibrations will be sound comming out of the speaker cone or the ports.

Unless the mooving mass of the speaker cone is "significant" in comparison to the box mass and it is a very high compliance design.

Yep I have seen speakers walk (and big ones) and in most cases simply placing a hand on the box will show that the box is vibrating.

If you are looking to weight and or thickness of material to solve the problem alone, lots of weight and thickness is required to achieve significant results.
Judicious bracing and non resonant, mechanicaly damped design will get significantly better results.

examples of techinques to minimise panle resonance and vibration.

avoid square or symetrical structures.
brace any flat open areas of panel.
when placing braces try to avoid making geometricaly regular shapes when dividing the panel with the brace.
the front bafle is very weak, you've probably chopped more than half of it away cutting speaker holes, brace between speaker cut outs to restore strength.
bracing diagonaly can be very good it tends to make less regular shapes.
boxes that aren't cuboid tend to have less panel resonance problems but stay away from realy obtuse shapes they can do weird things too
Tension or compression braces that run front to back, top to bottom or side to side have value but tying oposite sides of boxes together does not help with panel rigidity they only resist the ballooning effect.

With a typical twin 15" box ( arround 600 x 700 x 900 typical)
I would fit a 100mm brace (edge on ply 20mm thick) across the baffle between the drivers to restore baffle strength, slightly diagonal if I could.

I would place one or two similar braces across the back panel avoiding the 1/2, 1/4 or 1/3 points.

Then two similar diagonal braces on the sides opposite diagonals on oposite sides.

because the top and bottom are usualy shorter boards and in pro audio they will usualy be sitting on the ground with anoter box on top. I dont usulay brace top & bottom.
but a brace here would be good too.
If I was to get keen I woud tie some of the braces across to the other side. But I usulay wouldn't because you have other work to do in there & too much going on in there is a pain.

Using these methods I can achieve better panel stifness from 15mm ply than would be achieved with unbraced 20mm, I would argue better than unbraced 25mm on a big box.
Believe me that weight and cost saving is important when its your back and your wallet.

the same principles can be scaled for smaller drivers and boxes.

Very commonly neglected is bracing the baffle where the strength has been greatly reduced by cutting the speaker holes.
I Have seen very few speakers apart from my own with braced baffles.

It has been my observation that as boxes move from 4", 6" 8" sort of sizes up to the 12", 15" 18" sort of area, the structural strength and rigidity of ply becames more attractive that the deadness and weight of MDF.

I would have no problems with a small box for a 6" driver say 8 to 12 litres made out of 18mm MDF being unbraced but geting up into 80 to 120 litre boxes the panels will realy start to be flexible unless you are working in 32mm.
get up in the 200 litre area I don;t care what you are working in you need bracing.

cheers

Harry72

20th December 2006, 11:26 PM

Yes thats why mines 36mm thick and radially X braced, the reason it moves has nothing to do with the box "vibrating"... its the floor boards underneath it the whole floor is resonating, I cant turn the level up much as it bumps/resonates the DVD disc... and the windows of the neighbors across the road!
Not bad for a single 12" driver(adire shivaIII)and only 350wrms, its a HT sub so its tuned to 20hz for LFE its not much good for traditional music styles but ok for bass heavy stuff like MuDvAyNe or that teckno stuff.

soundman

21st December 2006, 02:27 PM

Well harry, theres your problem right there......... you need to fix your floor:D :D :D .

In sufficient rigidity and mechanical damping in your floor.:D :D

cheers

normanjr

30th January 2007, 05:05 PM

I've built a number of cabinets out of timber and mdf and found mdf produced better results for all the reasons identified above.

I dont think you really need the whole vacuum kit to do the veneering, you can achieve very good results with just a sturdy roller and patience.

Precise construction and correctly sizing the enclosure for the driver/s are important. Spending time planning the design and construction of your enclosure will pay off later on when it comes to listening, but I think you'll find after successfully building your first set of speakers, you'll be looking for excuses to build more! I'm already up to my 5th subwoofer iteration, and have far too many idle speakers around...good luck!

woodbe

30th January 2007, 08:04 PM

Exactly how much air mass do you think you are mooving?

I would be looking for other reasons why the "vibration" is causing the box to move.

This was a big name big-ass sub. 15" driver. Dead to touch. It's always been a problem child, rattles even on concrete. I think the boffins in the backroom out did themselves :)

Petebass

7th February 2007, 08:26 AM

Except... in the case of a down-firing subwoofer :)

My Brother has one of these, and on a polished floor, it needs to be anchored in heavy bass or it walks across the floor, and it's no lightweight. lol... soundman is right, that thing is vibrating. That's a massive loss of acoustic power.........

Trouble is, you'd be amazed at how many commercially made pro-sound cabs can be made to walk across the room. Most commercial cabs aren't braced. The theory is that it's cheaper to make cabs unbraced, and to compensate for any loss of rigidity they just make the ply thicker. That's why a lot of pro sound cabs are made from ply that's an inch or more thick. I've made cabs out of 12mm ply and went to the trouble if bracing it properly. The result is a lightweight cab that can't be made to walk across the room. No vibrations. Properly braced, ply can work brilliantly. And as point out by Harry, any losses in the compromise are easily accounted for with a comon sense approach to speaker placement.

Speaker design is full of compromises. In pro,sound, you're constantly juggling with the Rigid Vs portability equation. Let's face it, the ultimate speaker enclosure would be concrete. That's completely impractical, especially for pro sound cabs get picked up and moved several times a week. That's why most pro sound cabs are Ply and home Hi-Fi is often MDF.

soundman

8th February 2007, 11:36 PM

I'd have to agree that if your box is vibrating and walking you must be leaking energy badly.

It occurs to me that many of the current range of HIFI bass drivers they have simply increased cone mass in an effort to reduce resonant frequency.
Some of these drivers would have twice or three times the cone mass I would expect from a high power pro type driver.
Start whipping that back and forth and you will produce more vibration and less sound out..... this probaly accounts for the very low (by pro sound standards) sensitivity specs on some of these drivers.

I sort of agree and disagree about the horn loading thing.
I grew up with big horn loaded boxes like altec 816, 828 and 817 boxes which were all horn loaded.... while lots of others were using front loaded stuff and some of the early band pass stuff.

I remember one job I was on we had some horn loaded boxes subd in to supliment the clients bose rig......his tandem tuned bass boxes were beside the horn loaded boxes........ the TT boxes sounded like they werent pluged in.:D :D
Believe me I am very pro hor loading.

BUT

to get an effect on low bass the horn does need to be big......very big.
To get maximum transfer efficiency the horn needs to be long and the mouth needs to be wide....... monumental proportions.

However the "turbosound bass device" (complete with lapsed patents and registered trade marks) did effectively fly in the face of a lot of excepted wisdom about the size and length of the horn required to achieve results in the mid bass region 80 to 250 Hz.

It is true that almost all major manufacturers are currently offering horn loaded designs in the ranges..... BUT..... almost without exception they offer a traditional bass ported design for low bass.

The old given driver argument in reality simply dosn't hold up in the real world.
Yess I've been guilty of making it my self in the past, but in reality there is such a large variation in drivers these days the argument comes unstuck very fast.
Lots of drivers will work well across a number of design types, other drivers will work very well in specific types, many drivers will disapoint if put in the wrong design.

One thing is certain......... what goes arround comes arround......When you've beed arround a while you recognise the latest new thing as an old thing from half a generation ago packaged in a diferent shape with a new trendy technical name.:D :D

The collumn is dead, long live the horn loaded stack.....the horn loaded stack is dead, long live the flown array....... the flown array is dead, long live the line array(oh isn't that a collum speaker?:? )..........The line array is dead,hail the horn loaded box (back again are we).:D :D

I notice that the transmission box that was popular in the 60's and 70's is making a resergence......... now where did i put those "J" bin plans:roll:

cheers

Petebass

9th February 2007, 08:29 AM

to get an effect on low bass the horn does need to be big......very big.
To get maximum transfer efficiency the horn needs to be long and the mouth needs to be wide....... monumental proportions.

However the "turbosound bass device" (complete with lapsed patents and registered trade marks) did effectively fly in the face of a lot of excepted wisdom about the size and length of the horn required to achieve results in the mid bass region 80 to 250 Hz.

I agree with pretty much everything you said. But in this bit, you didn't account for the effect of multiple horns cabs used in conjunction. If you line up several ported subs, they get louder, but they don't get much lower. If they were -3dB at 50 Hz on their own, they're still pretty close to -3dB at 50 Hz when you use several. Sure you end up with more bass, but that's because the efficiency in the frequency range between 50Hz and 100 Hz increases.

Horns are a bit different in that every extra cab effectively increases the mouth area, resulting in a lowering the cut-off frequency. If one cab was -3dB at 50 Hz, the second cab effectively doubles the mouth area, so the -3dB point could very well drop to 40 Hz (estimate only). Adding more cabs again lowers the usable frequency range further. This is apparently unique to horn designs. As far as I'm aware, no other cab type shares this characteristic.

Further, horns are quarted wavelength devices. So it stands to reason they work best in quarter space (ie open air divided by two walls, usually a floor and a one wall). Eight space (a room corner) is better again, but not often available in gig-land.

So if that Turbosound sub you mentioned was bottoming out at 80Hz in an anechoic chamber or outdoors, it concievabe that it could have got down to 50Hz or even 40Hz by placing it against a wall or by adding more cabs to increase the mouth area.

Gee I'm starting to sound like Bill :) Don't get me wrong I don't endorse horns in any big way, but they do have a place. I don't know that a coffee table qualifies, other than the fact that at least the speaker itself isn't visible making the whole thing a little more convincing as a piece of furniture.

One thing is certain......... what goes arround comes arround......When you've beed arround a while you recognise the latest new thing as an old thing from half a generation ago packaged in a diferent shape with a new trendy technical name.:D :D

The collumn is dead, long live the horn loaded stack.....the horn loaded stack is dead, long live the flown array....... the flown array is dead, long live the line array(oh isn't that a collum speaker?:? )..........The line array is dead,hail the horn loaded box (back again are we).:D :D

I notice that the transmission box that was popular in the 60's and 70's is making a resergence......... now where did i put those "J" bin plans:roll:

cheers Aint that the truth. I notice EA bass guitar cabs are available in Australia now and guess what - they're transmission lines.

soundman

11th February 2007, 08:51 PM

Block stacking front loaded boxes does not only increase the amount but also MAY result in a lower response....... but it depends and isn't as pronounced as a horn speakers.

I think its a factor of shaping the response and changing the curve..... the effectiveness depens on the frontal area of the box and the alignment of the box ( relationship of port freq to resonant freq).

All this is pretty well irrelivant to the home HIFi boys because they dont get to stack up 16 bass drivers a side nor do they get access to rooms worth doing it in.

cheers

johncee1945

20th November 2007, 08:14 AM

"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."

What do you mean "crackpot things"? You seem to have a closed mind.
Let us keep in mind the "comercially produced" are driven to a larger or smaller degree by profit considerations.
Development comes about through many contributions over a whole historical period including this very forum, and is always bound up with the needs and aspirations of society. It is always a social product of society and not bound up to any one group including the commercial operators. If it takes a contradictory road spiralling through its developmental life through trial and error including chance discoveries and mistakes - then so be it.

I added a 20kg block of cement to the base of each of my old Spender monitors and the sound improved, albeit slightly, but never the less an improvement. I base that on a 15 year familliarity with the speakers.

soundman

20th November 2007, 11:04 PM

no far from a closed mind.

there are a great many "interesting things" I have seen and heard of, that various "enthusiasts" love to fiddle with...... in my opinion they are nothing more than fiddles.......... the question I always ask is....... yes it ( whatever) may have made a difference.... but was that difference an improvement or just different..... and how do you prove that or quantify that.........if you can't prove it or quantify it...... it is nothing more than a personal impression another may not have the same taste and may not agree that it is an improvement.

if adding sand or cement to a speaker makes any provable improvement to the sound of a speaker the mechanical design of that speaker must have been deficient in the first place.........inadequate bracing, distribution of mass and a variety of other factors.

if such a speaker was a simple box made from 16mm chip board I rest my case.

the reason I say commercialy manufactured studio monitor......... because that is what the recordings are mixed on and these people have plenty of money to spend...... the top end studio monitors are far from a mass produced product in the true sence of the word.

there are time when fiddleing arround the edges with afterthaught patch up methods is all that is open .

But the preference surely must be adequate design in the first place.

I may have mentioned in the past that a friend of mine has a customer that insists on haveing his concert boxes made of 25mm ply.
My view is that it would be wiser and more effective to select the type and quality of the ply better and to achive better rigidity by introducing more effective bracing.

cheers

mandoman

14th June 2008, 10:17 AM

I have just joined this forum and came across this thread so am resurrecting what is now an old thread. There is so much rubbish talked about solid timber speaker cabinets, mostly from people how have never made one. I have been making solid timber cabinets for years, and if you get the design right and the timber right they WILL sound better then plywood or MDF. A peice of timber, MDF or plywood will resonate to a certain frequency which is determined by it's mass and stiffness. The length of time it will resonate will be determined by it's quality factor, which depends on the internal damping properties of the material. Some species of timber has a high Q factor e.g. Blackwood, Western Red Cedar. Others have a low Q factor, lower even than MDF - e.g. Jarrah. There is an enormous variation between timbers. You want to avoid high Q timbers for speaker cabinets, but if the timber has a lower Q factor than MDF then you are on to to good thing. Even better if the timber is stiff and heavy because then it will take more energy to make it resonate. Jarrah is excellent in all these respects. However, as already mentioned, solid timber is not dimensionally stable. Contrary to popular opinion, MDF is also not completely stable, but the difference is that MDF expands and contracts equally in all dimensions. Solid timber will expand and contract something like 20 times more across the grain than along the grain. You can safely ignore movement along the grain, but movement across the grain is a problem. It is a problem because with speakers the cabinet must remain airtight, but at the same time you need to allow for movement across the grain. A difficult problem, but not impossible to solve. You can't just glue up a piece of timber into a box and expect it to survive without splitting or glue joints to fail. With time and changes in weather one or the other is guaranteed to happen. How to solve this problem? Keep the cross grain dimensions as short as possible, and make the joints flexible. This sort of rules out big subwoofer cabinets, but tall thin shapes are possible. TL designs fit into this category, and this is what I have made very successfully. Jarrah is a very unstable timber and joints opening up more than 1mm is not uncommon. So, make sure the cabinet is at EMC before you put it together, and the joins must be be able to move at least 1mm.

So you can make very successful solid timber speaker cabinets, with some significant restrictions. Mine have survived through droughts and high humidity, and they definatlely sound better than MDF. I have made identical cabinets from MDF and Jarrah, and have chosen Jarrah every time because they sounded better. I believe that is because Jarrah has a lower Q factor than MDF and is heavier and stiffer than MDF so you get less sound coming from the cabinet. There are other timbers with similar properties, but most are more expensive and/or more difficult to get. Solid timber cabinets also look like a very fine piece of furniture, which gets solid approval from SHMBO, and that must be good.

soundman

14th June 2008, 10:12 PM

I think you are reading too much into this "Q" argument.

if your silid timber cabinets perform any better I expect it will be in mass alone.

If you have resonances of any form in the walls of your cabinet you have a bad strutural design problem.

If you want to compare benifits of various materials, Mass is a major consideration.

so if you have an MDF box that is the same mass as a solid timber box you may have a reasonable basis for the comparison.

Ther reason that both MDF and chipboard are chosen by some constructors is on the basis of mass. Such designers are relying on mass rather than good structrual design to gain rigidity in the boxes.

cheers

mandoman

15th June 2008, 11:17 AM

I strongly disagree. You will ALWAYS have resonances in the walls of your cabinets. This is basic physics. Any material will have normal modes of vibrations, but they will vary in frequency depending on the stiffness and mass, and the patterns of vibrations will also vary according to how the cabinets are braced. The amplitude will depend on the amount of energy involved, and the Q factor of the material. Making it stiffer will increase the frequency of the modes, increasing mass will lower the frequencies. You cannot just consider mass alone. The Q factor is vitally important. Why do you think many manufactures use damping materials on the walls of their speakers - to lower Q. You can see the normal modes of vibrations by using the Chlandi pattern method and I have written a paper on Chladni patterns in mandolins. The aim is to put the modal frequencies so high as to be irrelevant or so low as to be irrelevant, and/or to increaqse Q so the amplitude becomes irrelevant. e.g. increasing stiffness from bracing may increase the frequency of the modes of vibration into the treble region so the box is not then excited at all by the woofer.

MDF and chipboard are not used because of mass. There are plenty of other materials that have greater mass (and stiffness) - e.g. steel. However steel rings like a bell, i.e. has a high Q so is not really suitable. The fact is, MDF and chipboard are cheap and easy to work with and have a workably low Q. However, some solid timbers have a lower Q (and often higher stiffness and mass as well), but they are not cheap and not so easy to work with.

Petebass

15th June 2008, 12:53 PM

Why do you think many manufactures use damping materials on the walls of their speakers - to lower Q. Nope. They do it to prevent standing waves and internal reflections of the frequencies with wavelengths small enough to be fully formed within the cabinet - i.e. the mids and highs. And those are not the frequencies which make panels vibrate. They simply don't carry enough acoustic power. Lows and damping are completely independent of each other.

MDF and chipboard are not used because of mass. There are plenty of other materials that have greater mass (and stiffness) - e.g. steel. However steel rings like a bell, i.e. has a high Q so is not really suitable.
Steel is also so darn heavy it's not practical. You'd need 4 guys to get the cab into the back of the van. MDF and chipboard are used because they provide the necessary stiffness Vs Portability compromise. Even still, the demand for lightweight speaker cabinets is growing all the time....... I'm following a thread in another forum where someone is experimenting with a cab made of fibreglass. He figures if it's strong enough for aeroplanes and boats, he should be able to make it stiff enough for a speaker cab and achieve considerable weight savings. He's even posted considerable data regarding stiffness of various composite materials Vs Ply and MFD. I know you hate this guy and everything he represents. It may not work, but it's got a lot of people excited, myself included. Pardon me for getting bored when people start talking about weight being tonal God.

soundman

16th June 2008, 12:47 AM

mando mate, you have got the proportions of the physics all out of order.

there is no comparison between a hollow bodied string instrument and a speaker box.
In a holow bodied string instrument the cabinet is very light in comparison to the forces that excite it, and the cabinet is designed specificaly to transfer energy from the strings to the air.

In a speaker box the physics are completely different.....if you have any significant contribution from resonances in the walls of the cabinet you have major problems with the design.

Saying ALWAYS, is simply not true, it isnt popular now but in the 60's & 70's it was the done thing to make speakers out of concrete, or lead, or to fill the panels with sand or lead shot...... and a whole pile of rediculous things.

in the 80's & 90's, with the advent of a variety of methods of measuring and analising things we realised that the paranoya over panel resonance was simply not justified.

There are a variety of miscnceptions concerning how internal damping material effects speaker performance.

one thing that is certain is that light soft material typical of speaker stuffing will do absolutely nothing to improve the performance of the speaker walls, from the pointn of view of vibration or flexure at any frequency of significance.

The single most important thing to understand is that a speaker box is a preasure vessel and the single most important factor after having airtight joins is rigidity.

Mass in many cases is a direct result of attempts at achieving rigidity.

Now i wont try and say that mass and deadness (damping) arent important, because without adequate mass and structural damping you will have excessive panel resonances.

Assuming reasinably conventional construction methods and a reasonable thickness of material you sholud not be able to find a significant resonance in a speaker cabinet.......and if a resonance can be found, it will be insignificant in comparison to the far more significant imperfections that abound in speaker design........further that resonance will be insignificant in comparison to the "desired output" of the drivers.

There are a great many speaker boxes that do not have adequate box rigidity or damping on the market ( most of the tupperware speakers), but resonance is most certainly not the problem.

The major problems are non resonant radiation from the box sides, and the boxes failure in rigidity effecting the performanece of the box as a preasure vessel this playing havock with the "Q" of the enclosure as it relates to the theile/small design process.
The resonance we speak of here is not in the panel but in the volumetric design of the box.

In most cases the walls cabinet will not resonate BUT there will be a irregular stifness curve that causes the walls to work inperfectly to a greater or lesser degree at different frequencies.

even considering a mando, or voilin or conventional guitar, a well designed piece should not have significant resonances in the true meaning of the word, otherwise the instrument not perform smoothly across its voice range. it would sound peaky and nasty.
The goal it to allow the strings to freely resonate ( strings resonate in the true sence of the word) the body shoul as much as posible not resonate but simply act as a cuppler to connect the bridge to the air.

I think perhaps there may be some confusion in the use of the word "resonate". Musicians use the word an a manner that would not be considered appropriate in engineering or physics.

something that vibrates does not necessarily resonate, further it is a myth that everythig has a resonant frequency........(if we exclude neucular physics)

The music and HIFI industries are famous for giving imperfect explanations for actual physics and even more famous for getting effects out of proportion.

unrelated example.....yes I heard this one from a operaticlay trained singing teacher.

" Don't lean on the piano when you sing, the timber will take the resonance out of your voice"
Complete BS
the truth in the myth
" Don't lean on the piano when you sing, it will ruin your posture, which effects both your breathing and how you present your throat and head. this will effect both your power and you vocal quality"

Yes there are good reasons to have adequately rigid, sufficient mass and reasonable damping in speaker box materials, but if any of the above are inadequate you have bigger problems than panel resonance, especilay when you start playing with high power drivers.

cheers

mandoman

16th June 2008, 01:08 PM

"there is no comparison between a hollow bodied string instrument and a speaker box."

Rubbish. The physics is exactly the same, it is just the aims are diametrically opposed. A stringed instrument still has a helmoltz resonance and the physical equations are exactly the same. The difference is with a musical instrument you are aiming for a high Q - i..e lots of resonance from the walls of the box. In a speaker you want the exact opposite, but the physical equations ae exactly the same as in a musical instrument. I agree that when talking about "resonant" it is probably better to talk about normal modes of vibration because things such as boxes, flat plates, or musical instruments will vibrate at a number of frequencies, not just one frequency. Musical instruments are incredibly complicated with non linearities that years of research has not come up with much understanding of the physics of what makes an instrument sound good. Most of what instrument makers do it is done impirically. Fortunately with speaker boxes the situation is much simpler - the equations are well known, and try and reduce unwanted vibrations as much as possible

I still maintain that a speaker box will always have normal modes of vibration. Whether they are significant in terms of frequencies or amplitude is the question, and this is where the disagreement seems to arise. Using lead, concrete etc won't eleiminate the normal modes of vibration, but may reduce them (lower the Q) and/or shift the frequencies such that they then become irrelevant. If irrelevant then effectively they don't exist when you listen to the speakerl, but they are still there.

There are two kinds of damping used in speakers - (1) stuffing to reduce standing waves e.g. polyester, fibreglass, wool etc, (2) damping material to reduce resonances (oops, normal modes of vibration) of the box e.g. bitumen panels. I was referring to (2).

There seems to be an awful lot of misunderstandings with this topic.

Zaphod

16th June 2008, 04:41 PM

My preference for speakers is called 'constrained layer' construction. Use your hardwood, by all means. However, you are better off using MDF for the actual enclosure and then covering the whole lot with hardwood. Preferably with a compliant layer between. I like Sorbothane™ for that purpose. MDF has surprising advantages for speaker construction. Don't assume that hardwood is automatically superior. Like all things, attend to the inner surfaces with good damping and the whole thing will sound fine, as long as you build the box to the correct internal dimension.

soundman

16th June 2008, 10:44 PM

Im sorry to get narky but there are massive differences between speaker boxes and stringed instruments.

a stringed instrument is a box that vibrates when excited by strings via the bridge. the predominat output of the instrument is the cabinet vibrating.
the performance of the cabinet is not influenced appreciably by the strings and the strings are not appreciably influenced by the cabinet.
The predomonant physics is that of a complex vibrating mass....a complexity that to my knowelege at this point defies matamatical analasys in any serious detail......and the principle of which are still much argued about.
Further the performance and properties of the air volume contained within a stringed instrument while significant is only a very small part of the vibrating system. Violing for instance has a very low output from the "F" holes in comparison to the surface radiation.....in fact the "F" holes can be omitted with very little detremental effect.

the speaker box on the other hand in the ideal situation does not vibrate.
the predominant physics involve the relationship between the bass driver and the air contained by & within the box.

The maths and the analisis of such systems is pretty well researched, pretty well understood and the subject of a variety of commercialy available design programes.

I state again that the predominant physics in a speaker box is a relationship between the bass driver and the air volume contained in the box.
The vibrating surface is the driver cone its self and as the system transitions thru resonance the port in an enclosure will predominate in output as the resonance of the air in the box and the resonance of the driver interact

In speaker box design we strive and generaly achieve a state where the vibrations of the cabinet are insignificant and irrelevant.

I beleive you have some typical misunderstandings of the roll of damping material in speaker boxes........these misunderstanding and very common and popularly held.

The perdominant role of damping material inside a speaker box is to manipulate the "Q" of the air volume and its resonance which is used to play off against the resonance of the bass driver's sprung mass.

The supression of standing waves within the speaker box is a minor effect in both its importance and its effectiveness.
If the damping material was to be effective at supressing standing waves it would have to be significantly absorbtive at the frequencies involved and be at least a quarter wave in thickness.

For the damping material to be effective in supressing panel resonance it would need to be significant in mass in comparison to the box material... like at least 10% to have a measurable effect and it would have to be intimately connected to the panel, ie glued or bonded over its whole surface.

In the vast majority of cases this is not the case.

It is a common mistake to cover all interior sides of a speaker box with damping material, depending on design choices this may or may not produce a desirable effect.........in most cases with the types of drivers I use I would place damping material on 3 interior sides.
Some designs benifit verry little from damping material at all.
The amount of damping material is important in a design and can significantly effect both the optimum volume and a variety of other outputs.

It is interesting to put a box thru a simulator and change only the amount of damping and see what it does to the results.
Some designs and some drivers it will have a significant effect others less so.

All the important and significant factors in speaker box design can be redily calculated and simulated...........cabinet wall resonance is not one of them.

I sugest you get hold of some good science bassed texts on speaker box design.........there has been a great deal written on speaker box design..........there is quite a lot that is sound science............there is a vast quantity more that is out dated, misconcieved, partly factual or totaly rubbish.

I have been reading about speakers since I was a spotty youth, I can tell you I have read,... and held some misgiuided views in the past only to correct my views after more scollarly information came to my attention.

cheers

mandoman

17th June 2008, 10:57 AM

Of course there is a massive difference between a musical instrument and a speaker box, but the basic physical principles are the same. A musical instrument is far more complex and there are no matematical models that can adequately predict the sound. As you say, a lot of the sound emanates from the box. Speaker box models assume no sound emanates from the walls of the box which greatly simlifies the model. There has been a lot of research on violins, but little in the way of really useful information. As far as reading the research goes, I have to admit I stopped reading JAE papers when it became dominated by boring digital papers. Mea culpa, but I do have photocopies of all the original papers by Richard Small and Colin Thiele, and a swag of other classic papers on speaker crossovers and various other things. I was making so called D'Appolito WTW speakers years before they became fashionable.

I would strongly dispute the assertion that removing the F holes on a violin (or mandolin) will have little detrimental effect. That is just plain wrong. The surface area of the soundhole and the internal volume, and the stiffness of the plates, determines the helmholtz resonance frequency of the soundbox of the instrument (otherwise known as hte A0 mode). This most very definately does affect the sound. In musical instruments, box vibrations as well as air vibrations are both important to sound, and the frequency response is anything but flat.

If anyone thinks they have eliminated all box colourations in their speaker designs, just get yourself a full range elecrostatic or other open panel design, plonk it in your lounge room and listen. I did this some 8 years ago and never made another speaker for the next 3 years. However, eventually the challenge to try and beat the electrostatic was too great! Not there yet, but am getting close.

soundman

17th June 2008, 11:09 PM

If you claim that the "F" holes are esential have you proved it by building a violin ( or a mando) without "F" holes.

You can not say my assertion is wrong unless you can prove it.....I have heard expert testimony from one who has done the experiment and many besides.
This gentleman stated that he could easily build a violin that sounded good without "F" holes but no one would buy it. this gentleman was one of the top 5 makers in europe.

The sound hole contribution in a guitar is far greater than that of a violin or mando...... but yet we find quite a number of holow bodied acoustic guitars that do not have a sound hole opening, being commercialy made.

I most certaily did not claim that the response of a stringed istrument was flatt. but a poor one can be very nasty and peaky. Then you would probably call it a banjo.

The comparison between electrostatic speakers and any conventional speaker is not relivent, as the driver technology is completely different.
Nobody of inteligence will dispute that a good electrostatic will sound vastly different will have better transient response and less colouration than a conventional cone based speaker........but the colouration from the box materials will be the least of the difference.
For the most electrostatic speaker are impractical and irrelivent to most people.

you must also consider if the comparison is with a box of equal sofistication and price.

You may claim that the principles are the same but their reality and application of those principles is vastly different.
it is like saying that a dynamic microphone and 1000 watt bass speaker work on the same principles which they do....microphone will work as a speaker and a speaker will work as a microphone, buy the design practicality makes them do the job them do the job they werent designed for very poorly...the reality and practicality are vastly different. A microphone and a speaker are very much closer than a speaker box and an instrument body.

cheers

mandoman

18th June 2008, 11:55 AM

I'm getting rather tired of this pointless argument. Yes I have tried different soundhole sizes, and yes it does make a significant difference to the sound, and there is a wealth of violin research you can read, and no I have have not made a mandolin with no soundhole, and no I don't intend to because someone else already has done it and they won't do it again because the sound was not good. Done, and no more BS please.

We are drifting well away from the original topic. Bottom line is, yes you can make speakers from solid wood but with some restrictions because wood is not as stable as MDF or chipboard. The basic prinicples are - (1) keep cross grain dimensions as short as possible (2) make the joins so they can move. Since hardwood is usually stiffer and heavier than MDF or chipboard of the same thickness, and some woods have a lower Q, hardwood can sound better, but it will depend on the implementation. MDF and chipboard are much easier to work with, but hardwood can look handsome.

soundman

18th June 2008, 09:34 PM

but building a speaker of any significant size out of solid timber is totaly impractical, due to the instability of the timber

Apart from the fact that the "Q" of the timber has such a minute effect on the matter it isnt even worth bothering about.

cheers

mandoman

19th June 2008, 10:52 AM

Soundman, do you have anything positive to say? After so much carping and pedantic criticism and lectures on how to do research on musical instruments I wonder why I ever susbscribed to this forum. From now on I think I will stay with the boatbuilding forum where there is much helpful and useful information offered. My time is far better spent on building the next speaker which will be a mass loaded quarter wave tube (otherwise known as a transmission line with a port), made from solid hardwood. The cross grain dimensions will be a maximum of 21.5cm, which is close to about as far as I would go. Practical, yes. More difficult to design and build, yes, but so what!! It will be more of a challenge to design, will look far better than veneered MDF and get approval from SWMBO, and that is important to me. I have worked with MDF a lot in the past and got sick of it and the fine dust it produces. I would far prefer to work with wood, but that is my choice, and my experience is my solid wood speakers sound better than the indentical ones I made from MDF. If others want to build bigger speakers from MDF because of the advantages of MDF then go for it. Jeepers creepers, I am just trying to poiint out that it is not impossible to build speakers from solid wood. After all Sonus Faber do it.

Now that I am armed with such gems as mass is the most important thing, steel is too heavy, electrostatics are an entirely different matter, wood is totally impractical, musical instruments have an entirely different physics, etc etc, I think I should be OK now.

soundman

19th June 2008, 10:02 PM

I like solid timber as well as the next man, but I have not a positive thing to say about making speakers out of solid timber, because for a variety of reasons it is an impractical and uneconomic prospect.

I have also heard more than my fair share of hokus pokus and mumbo jumbo about speaker construction and HIFI in general and have a very low tolerance to this sort of ........ stuff.

There are plenty of pelple who will argue about the " significant effects" of minute, insignificant and largely irrelivant techincalities of anything to do with sound and music.

The vast majority of speakers cabinets encounterd will be structrualy inadequate.
There will in the vast majority of cases be much more obvious causes of inadequacy than choice of box material.

I put discussing the "Q" of a piece of timber used in a cabinet up there with the best of the pointless arguments I have come across.

As far as My gems you quote out of context.
Understanding the role of MASS is one of the most important concepts in physics. Mass is one of the most important concepts in sound but too few ever realise that.

as far as steel being too heavy, this is an over simplification sorry.
Steel has does not have a good enough strength to weight ratio to build a practical speaker, to gain sufficient cabinet rigidity the steel will be too heavy.......If you want a realy good discussion on strenght to weight ratio and the benifits of timber over steel I sugest you have a read of the "gudgeon borthers on boat building."

If you are going to discuss realtive merits of a material for an application, using a completely unrelated technology as an example is unhelpfull and irrelivent.
Sugesting that someone "gets" some form of expensive, obscure and esoteric technology as a means of setting them straight is nothing more than insulting.
So you own a pair of electrostatic speakers.... so.

Anybody who has any exposure to good information on the behaviour of timber will understand that is has a variety of stability issues that make it impratical for use in building speakers of any significant size.

and
If you can not grasp the dramatic difference between the physics of speaker cabinets that have a very well described behaviour and musical instruments that even at the highest level people still argue about, I wonder.

I think your main problem is that you come to this thread with your " guitar wisdom" expecting to "set us all right on the matter".

If you come to this forum, confident in your own superiority, i think you wont be arround long.

as far as "Sonus Faber ", never heard of them.
There are all sorts of people doing all sorts of weird things in the HIFI market.
Lots of those things are not reasonable, nor practical.
you can build a speaker out of a length of sewer pipe, that doen't make it good technology or practical.

I supose there is one way you could make a servicable speaker out of solid timber.
That would be to make it using marine epoxy and coat all faces inside & out, as per west system, is it reasonable & practical....... dont think so.

See you in the boat forum:D

cheers

mandoman

20th June 2008, 11:00 AM

Once again nothing positive to say, and it is starting to get unnecessarily nasty. If you want to be the only person contrributing to this forum then you are going the right way about it.

What materials one uses depends on one's individual preferences, biases and priorities. The different materials will mostly work with some advantages and disadvantages. My priorities are obviously different from your's, and insults ae not going to change that. Lets end it there and not get into a pointless slanging match. There are many other places on the net where one can discuss speaker buiulding and design in a more constructive manner.

soundman

20th June 2008, 11:47 AM

Ahh a case of pots and kettles, lets leave it at that.

Isaac Hunt

26th July 2008, 10:25 AM

Interesting discussion.

What material you use is not so important.All materials wil resonate-just differently.
What is important is that the sound of the box,drivers and crossovers come together to produce a nice sound.
You could call this their overall acoustic.This is the art of speaker design and what makes it so challenging.

Some speakers with lightly built cabinets sound great.The BBC designed Spendors and Rogers speakers like the LS3/5a from the 70s spring to mind.These used 12mm ply.Harbeth continues to make speakers like this and they are regarded as amongst the very best you can buy.

I used to own some Klipsch KG4 speakers.These are great sounding old speakers that work beautifully with low powered valve amps.I lead lined them because I thought this might improve them-but it completely ruined the sound.

Audio Synergy used to make solid jarrah speakers.They sounded superb.

stan_nesta

18th June 2009, 10:59 PM

mandoman,
don't pay attention, there are people in every internet forum who will engage in endless discussions for the sake of it, it's a part of life.

on a different note, i have built speaker cabinet from solid Australian hardwood, actually two pairs, one from Blackwood, one from Jarrah. they both sound fantastic (using Vifa drivers in a WTW, or D'Appolito configuration, but that is not important). I still have the Blackwood pair and don't think selling it.

As for the stability of solid hardwood it all depends how dry the timber was and how are the boards assembled. What I mean is if you produce a board from several pieces laminated together (like the kitchen benchtops), sealed and then finished with polyurethane you will have no problems whatsoever, my speakers (which are DIY) are nearly 10yo and there are no signs of cracks, twists, etc. It's all in the preparation and the careful exsecution of the project.

About MDF, avoid it at all cost, it's dull medium for sound reproduction, the reason speaker manufacturers use it is it's cheap and uniform, easy to work with.
For top notch sound use solid wood, plywood, or combination of the two, like laminating a plywood carcass with solid wood, can even be pine.The end result will be way superior to the densest and thickest MDF box ever built. You can even line your box with lead sheets for improved performance.

At the end, when someone who pretends to be an expert says he/she has not heard of "Sonus Faber" and discards them as a valid point, I simply laugh.
One of the most innovative and creative speaker companies for the last 20 years, on a par with Duntech in regard to design, philosophy, prices, awards, and someone ignores these facts completely...I find it unbelievable and a bit arrogant. When their flagship model Stradivari Homage sells for $40000US, I think that deserves some attention.

I simple Google search will provide tons of information, here are a few links:

http://www.sonusfaber.com/eng/home.html
http://www.audioconnection.com.au/brand-specific/67/Sonus-faber-Audio-Visual-Equipment-Electronics
http://www.internationaldynamics.com.au/brand.asp?id=17
http://www.sumikoaudio.net/sonus/index.htm
http://www.tivolihifi.com.au/index.php?main_page=product_info&cPath=6_26&products_id=238
http://blog.stereophile.com/ces2007/011407elipsa/

Regards

Stan

mandoman

19th June 2009, 11:56 AM

Thanks stan_nesta, I am over it and have since built 2 more pairs of speakers from solid wood. That now makes 6 pairs from solid Jarrah, solid Tassie Oak, and solid Tassie Myrtle, and not a single failure. Sure, the wood has moved, it has shrunk and swelled with the weather, but the cabinet design has taken care of that. The fact that I can make identical speakers from MDF and solid hardwood and the hardwood sounds noticably better is enough to convince me that the extra cost and effort is worth it, no matter what. They also satify the other half (which is very important). Arguing over the reasons why they sound better is somewhat pointless, and can get into a lot of speculative BS and denial of basic physics. The point is they SOUND better, no question about it, and isn't that what we all want? The argument that MDF is "better" for DIY becasue it is cheaper, more stable and easier to work with, but sounds worse is a little odd.

Ha yes, re Sonus Faber, I also laughed at that.

Petebass

19th June 2009, 12:43 PM

Mandoman you clearly feel pretty strongly about this, and that's perfectly OK by me. But it seems pointless argueing the point without setting out to prove it. We can end this argument quite easily! All you have to do is build a cab which is identical in every way to one of your Jarrah cabs, but build if out of ply or MDF. Then scientifically measure the frequency response. We could even get some people who are independent and free from bias involved in some double blind testing to see if they can identify which speaker is which by ear alone.

I'm not being a smart alec, I'm dead serious. I'm no stranger to building 2 cabs which are identical except for one important difference to establish whether or not said difference alters the cabs sound of performance. I've done it before, I'll do it again. And until you go to the effort of doing this, your opinions, as strong as they are, will remain opinions and will always be open to challenge.

mandoman

19th June 2009, 02:31 PM

Dammit, I have done it, but my ears and the ears of my other half did the measurements, not scientific instruments which I don't have. We both agreed that there was a significant difference, and we both prefered the sound of the Jarrah cabinets. I have done this twice with the same results (different speaker designs), and once where I could not hear much difference at all (much smaller cabinet). Maybe the differences are not significant as the dimensions get smaller, dunno.

Frankly I don't have the time, the inclination, nor the resources to prove it scientifically beyond any shadow of a doubt. It is rather a lot of work and time is short and better spent on other things. What I did convinced me and the other half. The differences were obvious to both of us. It would certianly be interesting to measure the differences in detail and gain some understanding of what is going on, but too late now the MDF cabinets are no longer. Everyone is entitled to their opinion, and anyone is free to build identical cabinets and do the measurements and listen themselves, and maybe come to different conclusions with different cabinets and the debate will continue. All I can say is that with my cabinets, and my cabinet design, with the 2 larger cabinets there was a significant difference in the sound of the loudspeakers, and we both preferred the Jarrah cabinets. Maybe it is wrong of me to generalise and have strong opinions on this because there is no absolute proof, but I only use MDF for prototypes now. Other people have done similar experiments and have come to similar conclusions. The last I saw was a report on one of the DIY forums where various materials were used and plywood came first, MDF last, so solid timber is not necessarily the best material.

Slashbot_427

20th June 2009, 01:27 AM

One thing I have found is the quality of the sound from speakers is in the ear of the beholder. 4 years of running a music rehearsal studio for rock bands proves it. Guitar stacks or keyboard amps may not be HiFi, but studio monitors try to be. The vast numbers of different musicians and studio ppl I have spoken to and heard play, and the number of different speaker systems I have heard shows that all have their merits based on what you want to do with them. A case in point: The modern guitar sound has been shaped by 5 or 6 decades of recorded music showcasing guitars using overdriven valve amps, with transformer output stages. If the electric guitar was invented in 1983 ( transistors) instead of 1933, would it have been defined by op amps and sound like a keyboard?. Maybe? I don't know. The over-driven valve guitar sound has become part of the accoustic heritage, and if you try to use a tranny amp it sounds a bit "wrong". If you take a classic guitar speaker, such as a quad box or open backed cabinet, and play a CD it through it, it sounds crap. So why does it sound great with guitar, but crap with a radio mix.

You can run all the calibrated tests you like on a speaker system, and get fantasticly flat or crap results, but there is no calibrating a human brain. There is a lifetime of accumulated learning that goes into interpreting any sound that is heard, and the effects of various parts of any audio system will be interpreted differently by one person or another. A persons brain, in effect, is the filter for the sound that hits the ear.

You CAN make a speaker that really is crap, just look at 99% of the computer speakers out there. Its the i-generation.

There are some physics involved in the design of speaker systems, but essentially the principle is that the actual driver acts as a transducer ( ie. it converts electrical energy into sound pressure waves) and the box you put it in acts as a filter. There is also another issue which is impedance. Not the 4 ohms or 8 ohms etc electrical impedance of the wires in the voice coil, but the impedance of the air, and the impedance of the speaker system as a whole. The speaker system is a transducer, so its job is to transform electrical energy, to magnetic energy ( in the coil gap) to kinetic energy (cone movement) to sound pressure waves in the air. The degree of impedance matching between all of these energy transformations, at each frequency of interest, will define the frequency response, and sensitivity of the speaker system.

There are specific compromises involved, which can be poked in one direction or another by tweaking the design. The smaller you make the enclosure the higher the order of filter the enclosure needs to be to reproduce the bass frequencies -which increases the phase shift of the pass band. This increases the phase distortion, which is almost never quoted in specs, but results in different frequencies being reproduced by the speaker system at different delay periods.

The sound pressure levels from a phase distorted speaker system may show a "flat" response from 20-20kHz, but the various frequency bands are arriving at the listeners ear at unrelated times, due to the phase error. It is tiring to listen to.

I have a pair of full range, single driver speakers from about 1960, in cabinets with a volume of about 250 litres each. The cabinets are a direct radiated design with a rear, phase-matched bass frequency horn from the rear of the speaker cone ported to the front of the cab. I have no Idea of the specs, nor do I really care. I find them very easy to listen to for a long time ( 3-4 hours) at quite loud volumes, and really enjoy them. There is a good clarity from the speakers, so they are easy to listen to, but they are coloured by the cabinets- they have a thick midrange. The cabinets are some sort of ply, which is obviously flexing and farting with the internal sound pressures, resonating with the mid range, and absorbing some of the high frquencies. I'm not sure that replacing the ply with solid wood would have that much effect.

Cheers

soundman

20th June 2009, 12:14 PM

I have to agree with slashbot, beauty is in the eye ( or ear) of the beholder ( beer holder) and it is very difficult to get any two sound guys ( even worse HIFI buffs) to agree on matters of taste. More so having knocked arround the pro sound and to a lesser extent the hifi indusrty for a couple of decades, I can tell you there are a great many out there with their ears on well and truly crooked.

back to the matter of solid timber cabinets........I have absolutly no doubt that you can build a sucessfull and reliable pair of speakers out of solid timber....BUT... you will need a great amount of care (or luck) to select an appropriately stable spiceis and suitable stock from that spicies....then employ approproate construction methods.

There are considerable advantages for the person of average understanding and skill to use typical sheet goods such as chipboard, MDF and plywood to build speakers.

The above two reasons are why in general people are advised not to build speakers out of solid timbers.

As for making a direct comparison between this speaker and that that are the same design but different materials. This is not valid unless appropriate structrual modifications are made to the design, particularly in larger speakers.

typical australian hardwoods will have significantly greater density and stiffness in comparison to most sheet goods.

MDF is a fine material for construction of (non portable) speakers and when it came out was raved about in the speaker construction press specificaly due to its density (mass) and deadness (dullness) in comparison to the popular materials in popular use at the time ( ply and chip).

However it must be understood that MDF is not particularly rigid in comparison to other materials. In comparison of like thickness, MDF has very much inferiour stuffness to both chipboard and most ply It will certainly have inferious stiffness to a nice piece of australian hardwood.
To confirm this all you have to do is build a few long span shelves. Tin munutes with a few boards and a few bricks will prove this.

If you are to get best advantage from MDF it needs to be thick and preferably well braced.
Most of the sucessfull designs I have seen in MDF have used very heavy section 20 and 25mm and even up to 32mm.

If you are to discuss the benifit of this material over that (regardless of use) correctly engineering to the best use of the material has to be considered.
So if you build two speakers of precisely the same construction but change the materials only, one of theose materials will be disadvantaged and will look inferiour.
It does not matter if it is an aluminium boat trailer V's a steel one OR a timber framed house V's steel one OR as we are discussing, Solid timber V's something else for a speaker cabinet......two products optimumly made from different materials will look very different.

As I have mentioned before...I think the suposed benifit of using "tone woods" in speaker boxes is as much BS as marking arrows on your speaker cable or painting your CD's green.

Panel resonance of any form has and always will be undesirable in speaker design. Any suposed advantage will come down to rigidity and mass.

In my experiance "dullness" experienced due to speaker box factors can always be traced to a failure in panel rigidity.
This is the main reason that almost without exception the plastic moulded "pro sound" boxes currently popular sound dull, coloured and muddy.....lack low mid presence and have poor bass transient response.
All you have to do is crank one of these up and feel how much energy is being radiated by the walls of the box energy that is lost to the speaker cone and the port.

On the subject of phase distortion......This is certainly a matter that I hear very little of these days......In the "golden age of reason" ( late seventies to early eighties) when there was a refreshing outbrake of honesty in the sound business, phase distortion and time alignment were very commonly discussed in the forums of the time, in sales material and in technical specifications.
However with the advent of computer sound and mass market HIFI and home cinema, we have gone back to sales spiel, smoke & mirrors, inparticular concentrating on and lying about POWER. Sound has passed from the hands of the bofin and enthusiast to the salesman and the ignorant consumer.

As for sayig someone is ignorant because they do not know of any brand name is an insult and displays extreem ignorance.
I am sure there are those on this forum that could sprout may significant names that most will never have heard of.....knowing or not knowing a name or brand means nothing.

Finaly.... I can not understand why someone would seek the aproval of a bunch of key punchers, before building somthing they plainly wnat to do anyway......"he go and build your solid wood speaker Youl Brunner" if it does not work you have leraned something.

Hell I have kept myself warm many winter nights burning bits of speaker box.

cheers

rrobor

13th July 2009, 07:47 PM

If you build your speakers out of a wood that doesnt resonate, IE tap it, if it makes a noise like a zylophone it aint no good, I would use redgum jarra or box. Id make the boxes a bit big, then line them with MDF glued in panels. Only issue you will have is the hernia from lifting the suckers. As to the quality of sound out,. You wont care , too busy admiring the boxes.

Sharpdon

14th July 2009, 10:31 AM

Interesting thread. I make speakers as part of my business, and they are almost all made out of solid woods. The wood type is not a concern as the speakers are dipoles and not box speakers. The sound is very open and natural. Siegfried Linkwitz is the designer and also gave a presentation at the most recent AES 126 Convention in Munich, speaking about Recording, Reproduction, and Delivery. You may find the information interesting. See: http://www.linkwitzlab.com/publications.htm#23 for this and much more.
I have these speakers and can say they do show flaws in recordings that I think the recording engineer would have omitted had their monitor speakers been up to the task.
You can make these speakers yourself with a documentation package and circuit boards he offers for sale. They do use active crossover networks, so require six to eight channels of amplification (60Watts per channel is recommended). I am sure you can find more information about these if you are interested. I am only suggesting this as I am a woodworker and and an audiophile who enjoys listening to music. I made all the speakers (out of hardwoods) shown in the band at the top of the Linkwitzlab page. I know there are Orion users in Australia, as I have shipped completed systems there and know there are some who have built these themselves. Some owners allow auditions of their systems, so if interested, you might inquire if someone near you would offer this kindness.