You are either joking or as you only joined in October, you don't know about Planet10. He probably has more designs and completed builds of his speakers than anyone one else on this site. Were talking thousands of builds, of his designs to his specs, which is usually baltic birch ply if obtainable and perfecting designs right down to the holey brace
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I couldn't avoid making the MDF = bad point.
It's throwing out the baby with the bad water.
You eliminate distortion but you also kill a lot of useful sound energy with it.
A thin to medium ply or a solid wood well braced and dampened with a variety of insulation materials will ultimately sound better vented and sealed. My favorite is 1/2 inch textured foam rubber
Some people take personal offense to that
It's throwing out the baby with the bad water.
You eliminate distortion but you also kill a lot of useful sound energy with it.
A thin to medium ply or a solid wood well braced and dampened with a variety of insulation materials will ultimately sound better vented and sealed. My favorite is 1/2 inch textured foam rubber
Some people take personal offense to that
Pardon my ignorance here but I am new to speaker building and so I have many, many questions.
I am under the impression that the whole point of a Hifi system is to reproduce sound accurately, not create sound. So while I agree that the wood type, shape, size, configuration, etc on an instrument is key, I don't see how that translates back into speakers. What is right for s violin is different than a piano or a guitar....and what about brass, drums, vocals, etc...they are not generated from wood to begin with?
I thought the whole point was to have a neural enclosure to hold the drivers that can reproduce all types of recorded sound in an accurate way? If speakers seem dry and lifeless it may be that the bass enclosure was built too large...not the materials.
I am not saying that test tones is wrong, I just have questions about the logic behind the statemens.
Thx
I am under the impression that the whole point of a Hifi system is to reproduce sound accurately, not create sound. So while I agree that the wood type, shape, size, configuration, etc on an instrument is key, I don't see how that translates back into speakers. What is right for s violin is different than a piano or a guitar....and what about brass, drums, vocals, etc...they are not generated from wood to begin with?
I thought the whole point was to have a neural enclosure to hold the drivers that can reproduce all types of recorded sound in an accurate way? If speakers seem dry and lifeless it may be that the bass enclosure was built too large...not the materials.
I am not saying that test tones is wrong, I just have questions about the logic behind the statemens.
Thx
Created sound would qualify as the distortion everyone wants to eliminate.
Transmitting sound on the other hand is the same thing your speakers are doing and a good cabinet material can help with releasing more of the good energy while canceling the bad if designed and built correctly.
MDF just cancels out acoustic energy period and you hear more of the speaker which is fine if you want your sound texture so be overwhelmingly artificial. It's kind of like people that think fast food tastes delicious?
I find it utterly disgusting.
It's not distortion until it bounces off the panels and crashes into the following wave. MDF more or less shatters the wave. Hence the sputtery sound I notice in vented enclosures made of these cheap composites and super thick laminates.
A good example of positive resonance is laptops.
Some higher end laptops have a small bottom speaker designed to turn your desk into a transducer. Lift your laptop up off a desk to find out, you'll know instantly.
Mine that recently died was about 5 times louder sitting on a plastic desk but hands down sounded the best on a wooden desk or table. Lift it off the desk, it turns into a whimper.
It's a matter of salvaging the good energy when removing the bad.
Lazy, cheap builders just discard both rather than use their brain and put in the necessary hard work.
I challenge anyone to build from a thinner ply or a solid wood, even pine to do this. Brace all corners/seams with 2x2 solid wood. Dampen 50% of the cabinet starting in the middle of all panels and towards the back. Don't dampen the speaker baffle and obviously, immediate sides, top and bottom. I like foam rubber floor mats and the good old fashion pillow batting.
I know with certainty it will shame an MDF or huge thick birch cab of identical design and drivers only with mdf or birch bracing and no dampening material.
Transmitting sound on the other hand is the same thing your speakers are doing and a good cabinet material can help with releasing more of the good energy while canceling the bad if designed and built correctly.
MDF just cancels out acoustic energy period and you hear more of the speaker which is fine if you want your sound texture so be overwhelmingly artificial. It's kind of like people that think fast food tastes delicious?
I find it utterly disgusting.
It's not distortion until it bounces off the panels and crashes into the following wave. MDF more or less shatters the wave. Hence the sputtery sound I notice in vented enclosures made of these cheap composites and super thick laminates.
A good example of positive resonance is laptops.
Some higher end laptops have a small bottom speaker designed to turn your desk into a transducer. Lift your laptop up off a desk to find out, you'll know instantly.
Mine that recently died was about 5 times louder sitting on a plastic desk but hands down sounded the best on a wooden desk or table. Lift it off the desk, it turns into a whimper.
It's a matter of salvaging the good energy when removing the bad.
Lazy, cheap builders just discard both rather than use their brain and put in the necessary hard work.
I challenge anyone to build from a thinner ply or a solid wood, even pine to do this. Brace all corners/seams with 2x2 solid wood. Dampen 50% of the cabinet starting in the middle of all panels and towards the back. Don't dampen the speaker baffle and obviously, immediate sides, top and bottom. I like foam rubber floor mats and the good old fashion pillow batting.
I know with certainty it will shame an MDF or huge thick birch cab of identical design and drivers only with mdf or birch bracing and no dampening material.
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Most instrument cabs are made from OSB...a bespoke one may be ply or solid wood, IF it was desired. Making anything but fire out of pine is a waste, except its nicer for kindling than MDF, which is mostly pine sawdust in my neck of the woods...
Planet10 can put it better than me so its best to quote ''Hign mass is a myth (lots of myths started by marketing departments to help them shrink costs). If you have 2 materials with the same stiffness, the light one is better. MDF is both less stiff and denser [than BB]. A good receipe for energy storage.........you should be comparing 3/4" MDF to 12mm BB. 18mm BB to 1 1/4" MDF. Particle board is better than MDF, but harder to work with."
I think that clears up the MDF 'thing'
Its where in the frequency range that energy becomes audible. It is energy and will come out somehow. If you can push it up out of range so as not to be excited by the driver as best as possible you're on to a winner.
I know some use fancy resins/compounds etc but I would be surprised if many $2.5k speakers weren't made of MDF. Its the low sale volume, big $$ items that 'should' used better materials. You'll also find you can buy the majority of the hi-end speakers drivers and make a better one yourself for less
I would say that bracing material choice would depend on bracing strategy, or vice versa. You could try dowels of metal or perspex, strips of dense real wood across panels, a plywood holey brace, clamping the front panel to the rear with threaded rod.
when you say bracing I immediately think of bracing the driver, which is the source of all energy/resonance in the speaker.
I have used pine battens and MDF battens with similar results, although the pre tension of the grain in pine may be a slight advantage. Ive also used ally angle to good effect. I plan to use square box in either steel or ally in my next build since windowed braces arent practical in my case..
I agree with this. To be honest I dont totally agree with the MDF arguement. Like for like then BB is stronger. Mass damping is useful tho. I work in an engineering job where both added stiffness and added mass are both used to tame problems. Both are valid approaches. Ive used 12mm MDF for a 17 liter box, heavily damped with lath lining to great affect, so i wouldnt say MDF is verboten. It is more transparent to sound though, and that needs to be taken into account during design, and tackled appropriately. Next build im using sapele ply and steel box bracing, and i think ill have no trouble getting the box vibrations down to a decent level. We shall see if i achieve it!
You lose.
You can start here: http://www.diyaudio.com/forums/planet-10-hifi/214897-minionken-fonken-gallery-pictures-only.html. For every one you see there there is at least one that is someone else's design.
dave
Pine can be made to work fine. More care with bracing and build topology is required.
http://www.diyaudio.com/forums/full-range/191159-woden-design-victor-fe166en-3.html#post2611790
these too:
dave
Well... The 'low level mush' that can be present with MDF, (theyre close to P10s words to me on the subject), I reckon is due to transparency. MDF has no pre tension, unlike ply or solid wood, and isnt up to par with ply under tension stresses. It still resonates but the lack of inherent elasticity means it is a more wideband resonator. Large bandwidth but low Q and thus benign harmonic signature. With the correct design it could be better than ply, trouble is that its a whole load more effort to get there.
Consider a box made of 1 inch cork or hard rubber. Would it sound bad? Perhaps the opposite. Would it leak sound like a sieve due to high panel compliance? Likely. Suitably braced though and the same could actually be rather good. A little like CLD, there are 2 other ways. Very rigid skeletal internals, compliant panels OR joints coupling them to frame. Or the opposite, weak compliant skeleton with very rigid panels. Both lend themselves to self damp due to the contrast in material attributes.
My main bugbear with MDF is its composition, which ive read is largely pine sawdust, and i avoid pine at all costs. Heavy card tube is better, but there may be many types of pulps used which would account for this. I ruined a brand new tenon saw recently cutting card tube... Hardboard (HDF?) would be far better than MDF, if it was available in more useful thicknesses.
@P10, that pine looks ok. Not at all like the balsa like pine over here. There is logic behind at least some of my assertions. Honest. Ive even gone as far as using angle iron for all battens, rather than pine. With the 'corners' particularly the rigidity was greatly improved. I guess im saying that the corner joint strength is more important if a rigid build philosophy is to be a success. If i get the corners strong enough then the panel rigidity is less important or more easily addressed, minimally.
Consider a box made of 1 inch cork or hard rubber. Would it sound bad? Perhaps the opposite. Would it leak sound like a sieve due to high panel compliance? Likely. Suitably braced though and the same could actually be rather good. A little like CLD, there are 2 other ways. Very rigid skeletal internals, compliant panels OR joints coupling them to frame. Or the opposite, weak compliant skeleton with very rigid panels. Both lend themselves to self damp due to the contrast in material attributes.
My main bugbear with MDF is its composition, which ive read is largely pine sawdust, and i avoid pine at all costs. Heavy card tube is better, but there may be many types of pulps used which would account for this. I ruined a brand new tenon saw recently cutting card tube... Hardboard (HDF?) would be far better than MDF, if it was available in more useful thicknesses.
@P10, that pine looks ok. Not at all like the balsa like pine over here. There is logic behind at least some of my assertions. Honest. Ive even gone as far as using angle iron for all battens, rather than pine. With the 'corners' particularly the rigidity was greatly improved. I guess im saying that the corner joint strength is more important if a rigid build philosophy is to be a success. If i get the corners strong enough then the panel rigidity is less important or more easily addressed, minimally.
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Stolen from the net:
Production Process:
MDF is a mixture of refined wood chucks and shavings that are ground into a fine fiber.The wood is heated prior to refining to give the finished product a stronger and more moisture-resistant surface. During refining, the wood is rubbed apart into fiber bundles (Reference 1). A binder or wax resin is added, which is usually urea formaldehyde, and the product is then heat pressed, sanded and sawed into very dense sheets. It requires about 23 inches of a fiber/resin mix to create one ¾-inch sheet of MDF, whereas it only takes about 4 to 6 inches of wood chips and sawdust to create one sheet of ¾-inch particleboard.
Production Process:
MDF is a mixture of refined wood chucks and shavings that are ground into a fine fiber.The wood is heated prior to refining to give the finished product a stronger and more moisture-resistant surface. During refining, the wood is rubbed apart into fiber bundles (Reference 1). A binder or wax resin is added, which is usually urea formaldehyde, and the product is then heat pressed, sanded and sawed into very dense sheets. It requires about 23 inches of a fiber/resin mix to create one ¾-inch sheet of MDF, whereas it only takes about 4 to 6 inches of wood chips and sawdust to create one sheet of ¾-inch particleboard.
Thanks Cal.
The 'rubbing apart' is the worst part since it destroys the natural fibrous adhesion of woodgrain in favour of a homogenous felted adhesion. Id guess that this trades high uni directional strength for weaker structure which is strong in all directions, but to a lesser degree.
Since the OP is concerning braces, id postulate that in brace apps, the rigidity of the material, ply or MDF is compromised.
Ive heard 'translam' designs criticised for using ply in its weakest dimension, yet window braces in ply or MDF both use the material in the weakest dimension. In this method of use, neither are as effective.
A fixed and welded skeleton of box tubing, placed just so, will out perform its equivalent.
A window brace in ply or MDF is itself a compromise, using a 'frame' of 2" or larger in 10mm LDPE would work too.
But a window brace of almost any rigid homogenous material would work way better.
Ply is cheap to some, not me.
The advantage in window bracing with ply rather than MDF, is alot closer to none.
Both are weak perpendicular to their stratus (strata?) Its the WAY the window brace uses the material to create strength is the key to its effectiveness, not the choice of ply or MDF
The 'rubbing apart' is the worst part since it destroys the natural fibrous adhesion of woodgrain in favour of a homogenous felted adhesion. Id guess that this trades high uni directional strength for weaker structure which is strong in all directions, but to a lesser degree.
Since the OP is concerning braces, id postulate that in brace apps, the rigidity of the material, ply or MDF is compromised.
Ive heard 'translam' designs criticised for using ply in its weakest dimension, yet window braces in ply or MDF both use the material in the weakest dimension. In this method of use, neither are as effective.
A fixed and welded skeleton of box tubing, placed just so, will out perform its equivalent.
A window brace in ply or MDF is itself a compromise, using a 'frame' of 2" or larger in 10mm LDPE would work too.
But a window brace of almost any rigid homogenous material would work way better.
Ply is cheap to some, not me.
The advantage in window bracing with ply rather than MDF, is alot closer to none.
Both are weak perpendicular to their stratus (strata?) Its the WAY the window brace uses the material to create strength is the key to its effectiveness, not the choice of ply or MDF
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Man, you've got me running to Google.
I know of Microllams, Parallams and even Timberstrands but the only Translam I know is when you stack your own cut outs together to make a cabinet, aka laminated.
The window braces I know are made of metal.
Can you help out the uninitiated here?
Ta.
EDIT: By window brace, do you mean something holds up your window mounted A/C unit?
I know of Microllams, Parallams and even Timberstrands but the only Translam I know is when you stack your own cut outs together to make a cabinet, aka laminated.
The window braces I know are made of metal.
Can you help out the uninitiated here?
Ta.
EDIT: By window brace, do you mean something holds up your window mounted A/C unit?
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