So I have some leads on Birch Ply may use a lower grade ply for bracing of a different hardwood species to make the bracing more effective as Charles pointed out - practices of Kef B&W ect... and not soft as Planet 10 suggest then use something like bitumen impregnated felt for damping the walls to deal with standing waves. Wow guess this whole cab material thing can get a little controversial. Well getting great ideas from all of you and a little entertainment factor as well so thanks .
Not quite uniform....
It's a pair of harder surfaces containing a spongy, interior that has no strength.
Gavin - speaking specifically of the Murphy brand of plywoods, the one you want to look for is the "Multi-ply" - which our particular distributor stocks with maple face veneer over the birch platform core. There are also numerous brands and distributors of "Euro" sourced ply that can be had with either raw (shop grade) birch faces, or at a higher price and in minimum quantities, pressed with almost any standard veneer you might want. If your plans are to cover with veneer, plastic laminate, trunk liner carpet - or with countless more hours than the enclosure fabrication probably took, paint - the shop grade face veneers are fine. Note that raw birch or even maple veneer faces can take a clear coat top finish very nicely, but can get splotchy if staining directly.
As Jerms noted, once you've penetrated the heat tempered face of standard MDF panels (which can hold a beveled edge sharp enough to do serious damage to your flesh
), the core is soft enough to scratch with a thumb nail. On the other hand, BB ply is softer on the face.
As Jerms noted, once you've penetrated the heat tempered face of standard MDF panels (which can hold a beveled edge sharp enough to do serious damage to your flesh
), the core is soft enough to scratch with a thumb nail. On the other hand, BB ply is softer on the face.If you have access to HDF, also called Medite, which is a heavier version of MDF, that would be a good choice. REAL Baltic birch is also an excellent cabinet material. But beware. There is some Chinese made plywood that looks a lot like BB but it's inferior to the real stuff. It splinters easily, has some voids, and it warps when you cut the sheet. If real BB is not available, cabinet grade plywood will work. Don't use regular plywood from the big box stores. That is inferior material for loudspeaker cabinets.
I'ld go with the birch however the MDF would sound better. Some time ago I had access to a finite element analysis computer program that analyzed vibration characteristics of various cabinet alternatives. One and 1/2 inch material worked much better than 3/4 so either build it with 2 layers or use a lot of bracing. Bass frequencies are more critical. Electronic crossovers are great but also expensive.
I don't understand WHY using different material for the bracing makes any difference. Explain further, please.
The other side to the coin is, would either material make any difference to the sound quality of a £10 full-range 3" driver in a 2.5 ltr sealed case ?
only the case has to be stated for cost v returns.
I'm aiming at DIY Audio Budget speakers, I'm attempting to make some desktop or surround sound satellites for about £40 a pair.
So at what price bracket do you say the cost of BB ply compared to MDF or off the shelf Ply gives a significant return to the audio quality?
only the case has to be stated for cost v returns.
I'm aiming at DIY Audio Budget speakers, I'm attempting to make some desktop or surround sound satellites for about £40 a pair.
So at what price bracket do you say the cost of BB ply compared to MDF or off the shelf Ply gives a significant return to the audio quality?
And then with budget will the difference if a ply at that level - will you here the difference with typical electronics sound card A/V receiver ect... used
So from a design stand point how valuable is the payoff or is looking at clever damping techniques so forth ans so on a better investment of time and cost. Interesting
Ummm....
Bracing vs no bracing is easy to figure out...
Bracing with different materials....
2c 2p whatever...
Materials have different "attractions" for sound frequencies. By sticking two diverse materials together it may be possible to avoid propagating certain frequency bands across a cabinet. Alternatively, combining the wrong materials in the wrong lengths, thicknesses etc may make matters worse.
For the DIYer; if differing materials are explicitly specified in plans, then it's better to follow them.
Likewise, if you have the kit and experience to accurately model, measure and refine differences in material selection, then, great.
J.
Finite Element Analysis
I know little about FEA. My boss (in 1991) analyzed the vibration of small hard disk drive parts using FEA. I was working on a software program to analyze the life of mechanical parts using the Weibull statistical distribution. We put the design of my proposed speaker cabinet along with the material specs - plywood, particleboard, and MDF. We varied the thickness of the material, along with varied bracing. By varying the input frequency, we could actually see an exaggerated view of the sides of the cabinet moving. We could not see how this really affected the sound.
The results: MDF was the best , 1 1/2 inch looked much better than 3/4 inch which surprised me. Bracing helped but not as much as the thicker material. Solid bracing (same width and length of cabinet with large holes in it) worked much better than just a board across.
However, there is a practical matter. MDF is not light and using thick MDF or 2 layers makes it twice as heavy. But my conclusion is that heavy cabinets sound better. How much better is a matter of opinion.
I know little about FEA. My boss (in 1991) analyzed the vibration of small hard disk drive parts using FEA. I was working on a software program to analyze the life of mechanical parts using the Weibull statistical distribution. We put the design of my proposed speaker cabinet along with the material specs - plywood, particleboard, and MDF. We varied the thickness of the material, along with varied bracing. By varying the input frequency, we could actually see an exaggerated view of the sides of the cabinet moving. We could not see how this really affected the sound.
The results: MDF was the best , 1 1/2 inch looked much better than 3/4 inch which surprised me. Bracing helped but not as much as the thicker material. Solid bracing (same width and length of cabinet with large holes in it) worked much better than just a board across.
However, there is a practical matter. MDF is not light and using thick MDF or 2 layers makes it twice as heavy. But my conclusion is that heavy cabinets sound better. How much better is a matter of opinion.
How did the driver energy get to the box walls?
What did you use as a determination of better?
dave
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