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Old 11th May 2011, 02:10 PM   #311
Squeak is offline Squeak  Denmark
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They might be dead to the relatively high frequency of a knuckle rap, but if you try the flexibility of MDF and plywood on longer pieces you will see a marked difference. MDF is much softer and more flexible for a given thickness.
It's not unusable for speakers, but you get a heavier speaker.
And also, I don't really like to work in MDF. The sawdust seems worse and the smell also seems more toxic. It doesn't smell like fresh wood, but more like the glue they use to bind the particles.
It also takes long for the panels to "de-fume" so to speak, sometimes stinking up the room for weeks.
MDF is not something I want to bring into my home if I can avoid it, esp considering all the health warnings.
I know ply is glue bonded too, but it seems much better sealed and/or that there is much less of it.
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Old 11th May 2011, 02:40 PM   #312
doorman is offline doorman  Canada
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Even if it were a decent building material for cabinets, the dust alone would be a deal-breaker for me. It is foul stuff, folks.
don
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Old 11th May 2011, 03:02 PM   #313
kec is offline kec  United States
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I agreee. It can't be good for your lungs (formaldehyde).
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Old 11th May 2011, 06:15 PM   #314
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Rapping the side walls of a cabinet is not a very good test, as playing music it will not encounter such a stimulus. Dead also implies low Q return, which, with music is more audible than a high Q resonance you would hear with an impluse input.

Take a mechanics stethiscope and listen to the panels while playing music. Pulling the tip away from the panel will give you very good indication of what the panel is really doing.

I am very glad that people are getting satisfactory results from MDF.

dave
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Old 11th May 2011, 07:46 PM   #315
jemraid is offline jemraid  United Kingdom
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One of the things in favour of MDF is not only its acoustic properties [or lack of them] that makes it very good for enclosures but also the fact that it can be CNC machined very accurately.

I believe that the flat packs that will be offered worldwide will be made from MDF on these machines and this in order to give a fair and justified return to the designers of this wonderful speaker*.

Jim

*especially with the MA CHP-70
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Old 11th May 2011, 08:29 PM   #316
chrisb is offline chrisb  Canada
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Quote:
Originally Posted by jemraid View Post
One of the things in favour of MDF is not only its acoustic properties [or lack of them] that makes it very good for enclosures but also the fact that it can be CNC machined very accurately.

I believe that the flat packs that will be offered worldwide will be made from MDF on these machines and this in order to give a fair and justified return to the designers of this wonderful speaker*.

Jim

*especially with the MA CHP-70
To describe MDF as having "lack of acoustic properties" certainly doesn't match my experience.


Having used both materials for years, there's no reason at all why high quality plywood can't be CNC machined to equal precision as MDF. Considering cost of machine time, as well as "manual" labour to cut bevels on the tops, fronts, and bottoms, the differential between ply and MDF becomes a much smaller portion of final job expense. A sturdy cardboard packing job will cost more than that in terms of material and labour.


Then there's expense associated with shipping weight.


Of course there are both "Lite" and NAUF MDF to answer the separate questions of weight and Formaldehyde off-gassing, but when we've used "lite" material, the vacuum suction hold downs on our CNC machine is actually detectable through to the top surface (IOW) it's kinda porous, and the particular brands of NAUF we've tried are noticeably softer.

Both are great products for the intended commercial applications of light weight wall/ceiling paneling, or to meet enviro concerns, but if for whatever reason plywood is not a project option, I'd be concerned about their performance in a speaker enclosure.
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Last edited by chrisb; 11th May 2011 at 08:52 PM. Reason: don't post from your iPhone, folks - or when sleep deprived
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Old 11th May 2011, 09:18 PM   #317
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Quote:
Originally Posted by chrisb View Post
To describe MDF as having "lack of acoustic properties" certainly doesn't match my experience.
Indeed. A continual stream of low level, low Q, time smeared music oozing out degrading the downward dymanic range.

Quote:
there's no reason at all why high quality plywood can't be CNC machined to equal precision as MDF.
Chris & i packed up the 1st of the flat-paks yesterday, and the CNCing is incrediable precise. Precise enuff that the corners are sharp enuff to cut the wrapping tape i was using.

Quote:
Then there's expense associated with shipping weight.
Not an inconsequential consideration. Besides making a better speaker, 15mm BB is considerably lighter than 18mm MDF, and with a flat-pak (with drivers) already getting dangerously close to the 30 kg limit of the postal system, could push it over that limit dramatically increasing shipping. Even the difference in size between 15 & 18mm might push the package over the 1m length restriction (one has to consider that MDF requires additional packing as it is a weaker material).

dave
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Old 11th May 2011, 09:22 PM   #318
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Quote:
Originally Posted by jemraid View Post
believe that the flat packs that will be offered worldwide will be made from MDF on these machines and this in order to give a fair and justified return to the designers of this wonderful speaker*.
Something the designers are strongly discouraging.

dave
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Old 11th May 2011, 09:52 PM   #319
jemraid is offline jemraid  United Kingdom
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Goodness!! I thought it was the other way round Dave :-)

Jim
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Old 11th May 2011, 09:55 PM   #320
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Quote:
Originally Posted by jemraid View Post
I thought it was the other way round Dave :-)
Not enuff context to know what you are referring to.

dave
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