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Speaker Cabinet Design Considerations

I like to use 3/4 MDF braced with 2x4 and 2x3. Also like to use 1/4 rounds on the front corners to help with diffraction. Coat the inside of the cabinets with Mass Coat to both completely seal and help dampen panel resources

Rob :)
 

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I like to use 3/4 MDF braced with 2x4 and 2x3. Also like to use 1/4 rounds on the front corners to help with diffraction. Coat the inside of the cabinets with Mass Coat to both completely seal and help dampen panel resources

Rob :)
thanks for sharing!

Searching for Mass coat turns up Mascoat. Only found it in 5 gallon pail, and is over $100/gallon. Have a better source that others might sample it?
 
I purchased mine 6 years ago directly from the manufacturer and was able to get a smaller 2 gallon pail. It was called Delta dB at the time. It has stood up very well over time and all I had to do was give it a good stir and used it a couple of months ago. I have used it for several speaker builds, shame you can't get smaller quantities.

Rob :)
 
....
-No parallel surfaces
-No sharp edges along the entire front
-A waveguide or a front that is spherical
-Not shaped like a box
-Not made from panels of regular wood
...
What about the front baffle material? I bet there would be difference when using (almost) non-porous material like aluminum and for example untreated plywood.
 
What about the front baffle material? I bet there would be difference when using (almost) non-porous material like aluminum and for example untreated plywood.

I'll bet that is part of why Genelec uses aluminum.
 
What about the front baffle material? I bet there would be difference when using (almost) non-porous material like aluminum and for example untreated plywood.
You mean beause of the porosity? The reason why aluminum is used is rather its high rigidity/stiffness and ability to be casted in the desired shape.
 
I'll bet that is part of why Genelec uses aluminum.
So we can extrapolate from that "aluminum baffle = good"? Or perhaps
You mean beause of the porosity? The reason why aluminum is used is rather its high rigidity/stiffness and ability to be casted in the desired shape.
In the day and age of 5-axis CNC machines and titanium printing 3D printers I find it hard to believe that "ease of manufacture of a desired shape" is a thing in the extreme high end.
 
In the day and age of 5-axis CNC machines and titanium printing 3D printers I find it hard to believe that "ease of manufacture of a desired shape" is a thing in the extreme high end.
Casting is much cheaper than printing or milling such a metal enclosure.
 
Casting is much cheaper than printing or milling such a metal enclosure.
It depends on production volume.
The cost of tooling for 3D printing is negligible these days but material consistency is a weak point. CNC machining is much cheaper than it used to be but both of them are very slow, so for small volume with few items to amortise the tooling cost and time of production not being a problem both of these make some sense.
The dies for a casting like the Genelecs will have been mouth wateringly expensive but the piece part cost and speed of manufacture very favourable for large production volume, which also allows the tooling cost to be amortised over considerable numbers.

The ideal manufacturing method is very production volume dependant but the cost of various manufacturing techniques is forever changing.
 
Once you are in the $$ $$$ or even $ $$$ range it makes little difference.
An average Genelec 80x0 model has a MSRP of $500 where it surely matters a lot if an enclosure costs 20$ or $200 to produce.

he ideal manufacturing method is very production volume dependant but the cost of various manufacturing techniques is forever changing.
Of course, was referring to the Genelec case, thus loudspeaker enclosures and production numbers.

CNC machining is much cheaper than it used to be but both of them are very slow, so for small volume with few items to amortise the tooling cost and time of production not being a problem both of these make some sense.
Also CNC machining doesn't make much sense for such thin 3D shells as a one step production as not only the speed but also the material waste is enormous, only for the final machining of a raw cast. You find though such one step machining at some "high end" $$$$$$$ loudspeakers where they feature the silly production as an advantage and reasoning for their price to the average fan who has no knowledge in such topics.
 
An average Genelec 80x0 model has a MSRP of $500 where it surely matters if an enclosure costs 50$ or $200 to produce.


Of course, was referring to the Genelec case, thus loudspeaker enclosures and production numbers.


Also CNC machining doesn't make much sense for such thin 3D shells as a one step production as not only the speed but also the material waste is enormous, only for the final machining of a raw cast. You find though such one step machining at some "high end" $$$$$$$ loudspeakers where they feature the silly production as an advantage and reasoning for their price to the average fan who has no experience of such issues.
I was agreeing with you.
I can't imagine anybody CNC machining a complex loudspeaker cabinet in ally!
My speakers are made from ally plate with "O" ring seals, the finishing and hidden fixings muct have made the manufacture very expensive but the production volume was probably very low. My main speakers have serial number 11 for example!
 
Aluminum is a good choice for a smaller active speaker for a number of reasons. It is relatively inexpensive, it is light and fairly strong and (as mentioned) is readily cast and machined. One other key point is good heat conductivity. Even with newer, more efficient amplification, still need to dissipate heat. Contributing to the internal heat is driving inefficient dynamic drivers at moderate to high levels.

When the cabinet gets bigger, it gets pricey and is why you still see it often applied selectively in baffles and braces for more premium speakers. In combination with composites (like MDF), the designer can mix and match it with aluminum to tame vibrational modes that occur with larger surfaces too. :cool:
 
So we can extrapolate from that "aluminum baffle = good"?

All relative, and it's not just the material. JBL could probably make better cabinets out of wood if they wanted to, it's just not common. Just like you could make a good speaker with an archaic cabinet design and slap some drivers on. It's just doesn't seem often that an excellent speaker will have those characteristics.

I'd think a cabinet or baffle material is better than another if it does more of the following:
-It decreases the internal volume of the cabinet the least amount possible.
-It is structurally rigid without the use of internal braces that decrease the internal volume of the cabinet.
-It can be use to easily make non-parallel walls and smooth surfaces to lessen internal reflections and diffraction.

The last one can be done with wood, but I'm not sure about the first two... Seems like you'd be shooting yourself in the foot.
 
from what I have experienced with drivers resonating front baffles, like the idea of a dampening brace for each driver (and in this case is for a speaker with an aluminum front baffle) :cool:
Absolutely true, my diy creature, has a 2 inch frontal baffle, two MDF sandwiched with glued roofing tar. And silicon gaskets.
 
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