Re: Re: Re: Re: Ply the music out..
We had a shoot-out like that at the 3rd VI diyFEST. Everyone could tell the ply box was different from the MDF... which ones people thought were best was another thing, but the comments were telling....
dave
larkinrulez said:
We had a shoot-out like that at the 3rd VI diyFEST. Everyone could tell the ply box was different from the MDF... which ones people thought were best was another thing, but the comments were telling....
dave
Re: Re: Re: Re: Re: Ply the music out..
When I want to build a BIB for a 6.5" Speaker, I can use the money I spare if I take MDF, to buy a Supravox HP165LB instead of a Fostex FE 167E .... I bet, there is a bigger difference between these drivers, than between MDF and ply 😉
When I want to build a BIB for a 6.5" Speaker, I can use the money I spare if I take MDF, to buy a Supravox HP165LB instead of a Fostex FE 167E .... I bet, there is a bigger difference between these drivers, than between MDF and ply 😉
I would see this as a reason to use MDF. The main role of wood (as a body) in musical instruments is to allow and enhance the resonating notes (frequencies) in it.
MDF is not used in musical instruments (considering speakers separately) because it would dampen the sound. This is what you want in a speaker, as little coloration of the music as possible.
Just my thoughts, Nic.
It amazes me that the plywood i use made in the Baltic (Russia usually) is cheaper after going halfway around the world, than it is in someplace where you could drive & pick it up (long drive mind you)
But then, some Europeans find it cheaper to buy drivers made in Denmark from the USA and have them shipped back across the Atlantic -- go figure.
(and the MDF is made right close)
dave
But then, some Europeans find it cheaper to buy drivers made in Denmark from the USA and have them shipped back across the Atlantic -- go figure.
(and the MDF is made right close)
dave
hmmmm...
I would prefer ply, if it would be cheaper, because it looks better...but I guess it makes no sense to order 5 or 6 sqm of BB in Russia 😉
I would prefer ply, if it would be cheaper, because it looks better...but I guess it makes no sense to order 5 or 6 sqm of BB in Russia 😉
MDF is a crummy material for PA speakers because it is heavy and easily damaged. This doesn't necessarily mean that it is bad for speakers used in the home..
Re: Re: Re: Re: Re: Ply the music out..
good point dave,
At the WD meets we have in england there are some differences but the constuction has to be taken into account,
i have heard good and not so good in ply and mdf.. but you can just tell the mdf if you know what your listening for..
Amplifiers seem to link in too in this respect.
with valve gear there is a tone from some ( cheaper) output transformers that seem to exagerate the sound of the cabinet
and all boxes resonate to a point..
the issue is what can you live with...
i have baffles now and every box i hear seems to sound in comparison
but i would still like to build a concrete and sand filled BLH in the future.. that would be closer to the 'baffle' sound hopefully..
steve
planet10 said:
good point dave,
At the WD meets we have in england there are some differences but the constuction has to be taken into account,
i have heard good and not so good in ply and mdf.. but you can just tell the mdf if you know what your listening for..
Amplifiers seem to link in too in this respect.
with valve gear there is a tone from some ( cheaper) output transformers that seem to exagerate the sound of the cabinet
and all boxes resonate to a point..
the issue is what can you live with...
i have baffles now and every box i hear seems to sound in comparison
but i would still like to build a concrete and sand filled BLH in the future.. that would be closer to the 'baffle' sound hopefully..
steve
I could make two boxes, one of BB and one of MDF, with exactly the same meaurements down to 2/100s of a mm (1/1000th of an inch) in precision on the CNC router at work. I'd just need someone with high quality measuring equipment, so we could settle this once and for all.
Having a mortgage and being on a very limited budget, if I want to build for the fun of it and just to see which enclosures I like best MDF is all I can afford. A 4' by 8' sheet of cabinet grade birch plywood is $40 while MDF is $12 for the same sized sheet. If you need two sheets of wood than it is a total cost of $80 compared to $24, more than 3 times the cost of MDF. Also, cabinet grade is not even close to the quality of the stuff Dave is using, the only places I have found that use that quality of plywood in my part of Washington charge $70 per sheet, which would be $140 for two vs. $24.
If I was to find the enclosure that was "it' for me than I would switch to nice plywood or even look into using real wood. How would I find out which I prefer between harvey's, mikasa's, a BIB or frugel horns for my fe126e drivers without listening to each of them in my living room first? There is no way I can build each of them with plywood on my budget so I am using MDF, now it is just a matter of having time for everything.
As for the health stuff, I cut with a mask and then leave my garage until the dust settles. Sanding plywood without a mask gives me a headach so I can imagine what MDF would do so I try not to breath it too much.
I know nice plywood is better, but having a choice between building with inferior stuff and not building at all I choose the first option. 🙂
If I was to find the enclosure that was "it' for me than I would switch to nice plywood or even look into using real wood. How would I find out which I prefer between harvey's, mikasa's, a BIB or frugel horns for my fe126e drivers without listening to each of them in my living room first? There is no way I can build each of them with plywood on my budget so I am using MDF, now it is just a matter of having time for everything.
As for the health stuff, I cut with a mask and then leave my garage until the dust settles. Sanding plywood without a mask gives me a headach so I can imagine what MDF would do so I try not to breath it too much.
I know nice plywood is better, but having a choice between building with inferior stuff and not building at all I choose the first option. 🙂
😀
Average Young's Modulus values:
MDF: MOE=0.53, Density=48
Chipboard: MOE=0.54, Density=29
Fir ply: MOE=1.2, Density=38
BB ply is even stiffer.
It's impossible to eliminate panel resonance in most practical speaker enclosures, unless it's built into the home as an architectural piece. As such, you have to change tack and decide how best to control it. What you don't want your panels doing is having their own natural resonance mode in the cabinet's main operational passband, where it will badly colour the sound. So, the two choices are to push the panel resonance up, or down. If you go with MDF (what one might call the brute-force approach) then you've gone for the the latter approach, & the object is to make panels massy enough to push their resonance mode below the Fc of the enclosure. 3/4in & 1in aren't generally enough -you'd need about 1 1/4 - 1 1/2in to do that effectively. Bracing helps too. The issue with very massy panels is of energy storage.
If you go with ply (or metal) you generally take the opposite approach. Although they do ring, you've pushed resonance up, above the main passband of the cabinet, to a point where the resonances are unlikely, or considerably less likely, to be excited. Both ways are valid, just as both takes: a speaker as an instrument, or a speaker as a reproduction device, are valid, by their own critera. Generally, I prefer ply, as it suits my take on design better, and it's less likely to cause long-term health problems (it's also self-damping to a degree, being of laminate construction). Pity it costs such a ludicrous amount in the UK, like any other wood.
Average Young's Modulus values:
MDF: MOE=0.53, Density=48
Chipboard: MOE=0.54, Density=29
Fir ply: MOE=1.2, Density=38
BB ply is even stiffer.
It's impossible to eliminate panel resonance in most practical speaker enclosures, unless it's built into the home as an architectural piece. As such, you have to change tack and decide how best to control it. What you don't want your panels doing is having their own natural resonance mode in the cabinet's main operational passband, where it will badly colour the sound. So, the two choices are to push the panel resonance up, or down. If you go with MDF (what one might call the brute-force approach) then you've gone for the the latter approach, & the object is to make panels massy enough to push their resonance mode below the Fc of the enclosure. 3/4in & 1in aren't generally enough -you'd need about 1 1/4 - 1 1/2in to do that effectively. Bracing helps too. The issue with very massy panels is of energy storage.
If you go with ply (or metal) you generally take the opposite approach. Although they do ring, you've pushed resonance up, above the main passband of the cabinet, to a point where the resonances are unlikely, or considerably less likely, to be excited. Both ways are valid, just as both takes: a speaker as an instrument, or a speaker as a reproduction device, are valid, by their own critera. Generally, I prefer ply, as it suits my take on design better, and it's less likely to cause long-term health problems (it's also self-damping to a degree, being of laminate construction). Pity it costs such a ludicrous amount in the UK, like any other wood.
I thought we had this debate a while back when one member built cabinets from ply and mdf and measured the differences (effectively zero). BBC research in the 1970s came down in favour of ply but that was ahead of blockboard, solid wood - MDF was barely available then. It also showed that 9mm ply was easier to tune than 18mm to avoid audible resonances. Try here for the paper.
Personally, I prefer ply for the ease of handling and the reduced dust but I'm agnostic on the acoustic benefits. Different materials require different bracing and damping so it's difficult to compare like with like and it may be that ply works so well in horns because of the inherent bracing. For sealed or straightforward boxes, you can probably make both materials work.
I haven't the knowledge or skill to make a musical instrument so I'd prefer that my loudspeakers remained loudspeakers.
Personally, I prefer ply for the ease of handling and the reduced dust but I'm agnostic on the acoustic benefits. Different materials require different bracing and damping so it's difficult to compare like with like and it may be that ply works so well in horns because of the inherent bracing. For sealed or straightforward boxes, you can probably make both materials work.
I haven't the knowledge or skill to make a musical instrument so I'd prefer that my loudspeakers remained loudspeakers.
planet10 said:
Sure. But I've yet to figure out how make a hardcopy of my listening experience. Xeroxing each side of my head doesn't seem work. I've also considered the Van Gogh solution but I don't know to post it on the this messageboard. Pins seem to ruin the screen. Please help.
it still sucks! (MDF that is).(a littled long winded)
please, this is not intended to create a division between folks here on this forum.
Having said that, I'll consider this an MDF (read: "dead") issue.
Budgetary concerns are real, and I guess we canucks have it pretty good here regarding the cost of wood. WEe've had good trading relations with the US , Cuba, USSR , the UK etc forever. Most folks around the globe luv us canucks and are as willing to trade with us as we are with them. We can actually buy real Cuban cigars here legally, get good prices on Baltic Birch ply, and enjoy "most favoured" trading status with the UK (so fine scotch and good beer can be had in most towns of any size). Oh and our dollar at par with the US one helps when importing goods into this country, but hurts our exports.
There are a few points here I think worth commenting on, and then I'll carry on my merry way. Loudspeakers are a musical instrument. How they reproduce sound has a profound effect on the listening experience. put a mediocre driver in a good quality box, vs a good quality driver in a poor quality box.
The material the box is made of has a significant effect on the loudspeaker. Remember that the driver /box is a system, and as such behaves in a particular way, particular to that system. I believe that the quality of the enclosure is directly related to good design and implementation, including the choice of materials. I also believe that Baltic Birch is a better material than MDF, unless cheap furniture is what you want. As [pointed out earlier, the BB ply has a better stiffness to weight ratio, and as such should be able to create a stiffer enclosure without resorting to "brute force" constructions, including granite, concrete, etc.) If you really dig the NRC sound, then by all means build as massive a cabinet as one possibly can.
Some here might remember the Celestion SL6 monitors, and the SL600s. AFAIR, the only difference was the enclosure materials, the SL6 used wood/MDF whilst the SL600s used Aerolam, an aluminium "honeycomb" of sorts used in the aerospace industry. Both speakers had their fans. If you consider the original three points I made in my previous post, the concerns I raised were based on energy storage, health and breathing of MDF. As BB ply is a gluded or laminated sheet good, there is no opportunity for it to breath. . So all concerns I originally made have been addressed.
Apparently apple ply is supposed to be very good for enclosures as well, but difficult to get here. Certainly a more cost conscious choice for the baby pigeons down south , given that it is a domestic product.
sleep time now. enjoy the discussion folks.
stew
please, this is not intended to create a division between folks here on this forum.
Having said that, I'll consider this an MDF (read: "dead") issue.
Budgetary concerns are real, and I guess we canucks have it pretty good here regarding the cost of wood. WEe've had good trading relations with the US , Cuba, USSR , the UK etc forever. Most folks around the globe luv us canucks and are as willing to trade with us as we are with them. We can actually buy real Cuban cigars here legally, get good prices on Baltic Birch ply, and enjoy "most favoured" trading status with the UK (so fine scotch and good beer can be had in most towns of any size). Oh and our dollar at par with the US one helps when importing goods into this country, but hurts our exports.
There are a few points here I think worth commenting on, and then I'll carry on my merry way. Loudspeakers are a musical instrument. How they reproduce sound has a profound effect on the listening experience. put a mediocre driver in a good quality box, vs a good quality driver in a poor quality box.
The material the box is made of has a significant effect on the loudspeaker. Remember that the driver /box is a system, and as such behaves in a particular way, particular to that system. I believe that the quality of the enclosure is directly related to good design and implementation, including the choice of materials. I also believe that Baltic Birch is a better material than MDF, unless cheap furniture is what you want. As [pointed out earlier, the BB ply has a better stiffness to weight ratio, and as such should be able to create a stiffer enclosure without resorting to "brute force" constructions, including granite, concrete, etc.) If you really dig the NRC sound, then by all means build as massive a cabinet as one possibly can.
Some here might remember the Celestion SL6 monitors, and the SL600s. AFAIR, the only difference was the enclosure materials, the SL6 used wood/MDF whilst the SL600s used Aerolam, an aluminium "honeycomb" of sorts used in the aerospace industry. Both speakers had their fans. If you consider the original three points I made in my previous post, the concerns I raised were based on energy storage, health and breathing of MDF. As BB ply is a gluded or laminated sheet good, there is no opportunity for it to breath. . So all concerns I originally made have been addressed.
Apparently apple ply is supposed to be very good for enclosures as well, but difficult to get here. Certainly a more cost conscious choice for the baby pigeons down south , given that it is a domestic product.
sleep time now. enjoy the discussion folks.
stew
Formaldehyde is no longer a problem with modern, quality MDF
In Australia, we now have a situation where quality MDF (perhaps all MDF) doesn't have a problem with formaldehyde content.
The current advice to users is essentially: "If you adequately control the exposure to dust - ie with local extraction - then you'll be adequately controlling any issue of formaldehyde".
The levels in MDF are much, much lower than they used to be.
Formaldehyde, as a chemical, still warrants caution, but it's no longer to be regarded as precluding safe use of MDF by the hobbyist.
cheers
Doug
In Australia, we now have a situation where quality MDF (perhaps all MDF) doesn't have a problem with formaldehyde content.
The current advice to users is essentially: "If you adequately control the exposure to dust - ie with local extraction - then you'll be adequately controlling any issue of formaldehyde".
The levels in MDF are much, much lower than they used to be.
Formaldehyde, as a chemical, still warrants caution, but it's no longer to be regarded as precluding safe use of MDF by the hobbyist.
cheers
Doug
I'm looking at ply from my local Home Depot. It has a nice maple veneer and is only $15 for a 24"x48" sheet. Is this baltic or fir?
It is likely a mix of maple and birch. They used to carry that in the stores in the Tacoma area and I can no longer find it.
Colin said:
John never had a chance with his measurements. (there may have been data buried in the impulse but all he could get out was gross FR.
The nuances we are talking about are 20-40 dB down from the main signal.
dave
Re: it still sucks! (MDF that is).(a littled long winded)
Apple ply is something available to us, but considerably more expensive than BB.
dave
Nanook said:
Apple ply is something available to us, but considerably more expensive than BB.
dave
gnugear said:
Of more interest (to some extent) than what it is made of, is how many layers it is made of... 12mm BB is typically 9 layers. The more layers the better. As an example, Bill Perkins built his cabinets out of a plywood he made out of 7 layers of HDF... it wasn't bad at all.
dave
- Status
- Not open for further replies.