Is MDF or plywood better for speaker cabinets?

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frugal-phile™
Joined 2001
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I bought a pair of home made corner cabs at a church sale and turned them into subs. There is no bracing just 2 layers of 3/4 inch plywood. Those are the deadest cans iv ever worked with. Put a glass of water on top and crank it up and the water is totally still.

I bet they were heavy. We acheived the same with 15mm braced ply, and a pair of push-push 10”. The cabinet could be picked up with a couple finger sin the driver cutout. Much harder when the driver's mounted.

dave
 
I will add one more insight from the world of aircraft structure engineering: we always strived to make structure as stiff as possible. high stiffness was good... both for static loads and dynamic loads. Due to weight constraints, structure always has quite a bit of flexibility. Weight is harsh limit in aircraft design, as every gram of structure is one less gram of payload or fuel. So we learned to deal with flexible structure... it causes all kinds of complications such as deflection-dependent load paths, secondary bending, aeroelastic issues...

Since the structure could never be as stiff as we would like, we often turned to damping to control vibration. This is particularly true with delicate equipment... it often was mounted with carefully tailored damping mechanisms. Two things to keep in mind (1) damping was a necessary band-aid, a "corrective action" because the structure could not be made as stiff as we would have liked. (2) the damping was carefully tailored, based on flight test and lab tests, by engineering experts whose whole career was dedicated to vibration problems.

If I did not already know that CLD cabinets actually work in both a DIY setting as well as production, I would be very skeptical of the approach. I would be skeptical that the necessary testing and analysis could be actually be completed. I would be skeptical that enough damping could actually be built into the cabinet walls to achieve a critically-damped structure... However, it obviously can be made to work, and there are successful production and DIY speakers using CLD. So the proof is in the doing...
 
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Joined 2018
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13 ply BB is 18mm. It is avaialble in a range of construction quality. We used lots & lots of it (and 15, 12mm) but switched over when we found the quality of the BB we were getting was getting poorer*, we switched to the Murphy Ply birch plywood which was of a higher quality. A quality Baltic core which they skin with maple veneeres (sp ominal 18mm gets 15 plies).

*(BB can come from Finland, the Baltic States, Russia & China (list in our experience shows a general decrease in quality).

The BB we were getting did not cost a whole lot more than decent MDF.

You spent big bucks on the drivers, don’t skimp on the final box.

PlybooStrand Bamboo Plywood and Veneer | Plyboo

dave

Can you figure out how to ply 3 ply bamboo sheet goods from that site?

All I can see is flooring and architectural panels...

Thank you,

David.
 
Like planet10 says there has been a lot of changes in sheet goods compared to the high standards of the 70's-80's. Back then lumber core was the king of quality, flat panels. Job built kitchens used that for cab doors because of the superior quality. When FinPly hit these shores, boy, that changed the way we looked at plywood construction here. Those panels were flat and hard. Excellent machining characteristics and very good finishing performance. Russian BB came along, was more cost effective and like everything else I think they used that roll out to gain a larger market share. Then the quality started to decline, heh, who would of thought ;0

I think bamboo can be hit and miss. I've seen delamination issues first hand and it ain't pretty. As Dave says, Murphy makes a fine panel. Their face veneers and glue up are exception today. A guy has to weigh labor/material costs to justify not using these quality products. A little more up front but if you have the necessary equipment, it's well worth the investment.
 
Viscoelastic material

Loudspeaker with a sandwich of cast aluminum and viscoelastic material:

Speaker Cabinet Design Considerations | Page 8 | Audio Science Review (ASR) Forum

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