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Old 25th September 2012, 10:50 PM   #11
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I think you have to go to/for measurments to fully understand the different properties of different materials. There seems to be no material to be the unquestioned winner.

Rather than using just one material, combining some can make things better. Even if I rely on measurments some intuition is needed in my opinion. Which materials are worth to consider in the combined approch. Even a simple thing like "painting" MDF with epoxy changes the MDF to a rather different nature in this respect.

But I also think this is an area where peopleīs beliefs are more dominant than real knowledge.

I studied e.g. the measurments made by the renown Peter Comeau (working for
IAG) published in the July 2008 issue of Hi-Fi World. It was revealing!

There is a comparision between some High end loudspeakers in the German magazine Stereoplay issue 5/2012 where loudspeakers of quite differnet concepts are compaired by measurments to the resonances of their enclosures,
aluminium, slate, epoxy based materials and glass fiber sandwich between"end grain oriented " balsa wood leads to rather different results.
Inner damping, e-modulus, the weight of the material in question; all is important.
So between Baltic Birch plywood and MDF it should be a simple answer But I donīt get it, makeng a good speaker has to be more complicated. I can quote some results from Peterīs measurments but itīs better to read the whole story. The same for measurments in the Stereoplay 11/2006 supplement. Even more interesting to me is the interview with Andy Payor of Rockport Technology in The Absolute Sound issue 214.

By no means I intend to be rude by ignoring a simple question. But I believe you have to recognize the compromises involved in loudspeaker design and building. And going beyond the simple answers may make sense, the answer is dependent on what you want to achieve.
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Last edited by The golden mean; 25th September 2012 at 10:55 PM.
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Old 25th September 2012, 11:12 PM   #12
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Quote:
Originally Posted by The golden mean View Post
Even more interesting to me is the interview with Andy Payor of Rockport Technology
His techniques are very good, very expensive too, Two lightweight and very stiff shells separated by a highly damped dissimilar material.

We are finally getting to implementaion of a technique that would have much of the rationale of the Paylor boxes -- a technique i've been thinking about for well over a decade, the pieces are just starting to fall into place.

Using sheets made from multiple materials (contrained or not) can take things to another level (performance, cost, and effort . The question i consider is given a single sheet material what works best? Most diyers, especially begineers, are not prepared to tackle anything beyond single sheet material.

As a frugal-phile(tm) it is important to me to get best bang for the buck. And it ain'td MDF, it does not meet the requirements we demand wrt DDR. Chris and i have both had our 10,000 hrs of critical listening training and we are very picky.

dave
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Old 25th September 2012, 11:19 PM   #13
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... and its dust, though not considered a health and well being product, is way better than wood dust infused with formaldehyde based glue.
totally agree ... the dust from MDF is very fine and lord knows what is in the glue.
Actually, I consider MDF glorified cardboard.

Here is the article from Troels about chamfering the backs of a baffle.
I think with Baltic Birch, the chamfering can be pushed more than MDF.

chamfering driver holes
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Old 25th September 2012, 11:32 PM   #14
FozzZ is offline FozzZ  Canada
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It was mentioned in another thread that MDF can make a FR speaker sound "dead". If this is the main reason for using BB, than I understand where you're coming from.

As far as health risks, both materials use the same glue. Fiber board can produce fine dust, but a proper dust collection system will help this. Proper PPE (personal protective equipment) like dust masks should be warn when cutting any wood product. But that is another topic.

I know now this is a redundant topic, so forgive me for that.
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Old 26th September 2012, 12:12 AM   #15
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I have wanted to try a sandwich of Masonite and polystyrene bead board. The immediate problem is a suitable adhesive to glue polystyrene to anything. Ideas?

Bob
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Old 26th September 2012, 12:19 AM   #16
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I had seen somewhere that the material it self has a resonate point, BB was ~220hz, MDF ~280 or 300hz, and Particle-Board was~ 14hz. this intrigued me, so I build the Klaushorn with the three kinds of Material's. The PB was less resonance than either of the others, the MDF sounded more muffled. BB is better to work with and stronger.

regards Klaus
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Old 26th September 2012, 12:23 AM   #17
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Originally Posted by Bob Brines View Post
I have wanted to try a sandwich of Masonite and polystyrene bead board. The immediate problem is a suitable adhesive to glue polystyrene to anything. Ideas?
Here's a start:

Loctite PL 300 VOC Foamboard Adhesive from Loctite Adhesives

jeff
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Old 26th September 2012, 12:59 AM   #18
sippy is offline sippy  United Kingdom
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Quote:
As far as health risks, both materials use the same glue.
This is true, I suspect you missed my point...... average amature shop vac isnt all that hot with real fine particals and mdf is VERY fine, ply woods slightly larger as it does not start as homogenised dust.
As for the same glue - most likely, though mdf (I suspect) uses a fair dose more to make a board. Think about that one!

Quote:
Originally Posted by Bob Brines
I have wanted to try a sandwich of Masonite and polystyrene bead board. The immediate problem is a suitable adhesive to glue polystyrene to anything. Ideas?
PVA or Copydex
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Old 26th September 2012, 01:34 AM   #19
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Originally Posted by Bob Brines View Post
I have wanted to try a sandwich of Masonite and polystyrene bead board. The immediate problem is a suitable adhesive to glue polystyrene to anything. Ideas?

Bob
Aka a composite.

Is there a reason why you are going with polystyrene bead board ?
I think you are far better off with 400 weight styrofoam.
It can be purchased as small as 1/2" inch thick.

I've never worked with masonite (sorry if I am a wood snob).

Polyvinyl wood glue (aka carpenter's glue) will bond styrofoam to real wood just fine.
But I've never tried to bond the gloss side of masonite.

As always, regardless of which adhesive you select - try it on a sample first.
.
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Old 26th September 2012, 01:36 AM   #20
mp9 is offline mp9  United States
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Quote:
Originally Posted by bushhorns View Post
I had seen somewhere that the material it self has a resonate point, BB was ~220hz, MDF ~280 or 300hz, and Particle-Board was~ 14hz. this intrigued me, so I build the Klaushorn with the three kinds of Material's. The PB was less resonance than either of the others, the MDF sounded more muffled. BB is better to work with and stronger.

regards Klaus
any idea where Bamboo plywood fits in? I've been eying out bamboo cutting boards at Homegoods...thinking they're just the right size to build Scott L's small monitor for the A12P.
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