Speaker Enclosures

What is mdf?

Medium Density Fiberboard...good 'n cheap...and perfect for amateur efforts. Do you know what granite is going to do to your carbide (assuming you bought the best) drill bits and router bits? Stick with the easy materials...you'll have enough to worry about in voicing your crossover--and wait till you try to make the 2nd speaker a clone! Off-the-shelf drivers (esp tweeters) will match only within 1-2 dB, requiring more crossover tweaking to create a reasonable stereo pair that doesn't image like those funny-mirrors at the carnival! Yeah, speaker designing was fun, but now I leave it to the few pros who truly sweat the details with very careful custom-driver spec and matched-pair cloning. Material choice is quite secondary to transducer and crossover response issues. Sorry to wax pessimistic on you...I'm not really the grinch who stole Xmas, am I?..... I carefully voiced a 3-way 8/5/1 design a few years ago, and was surprised that a 1/3 dB change across 1.5 octaves in the upper midrange was so noticeable as a change in spectral character. After I was reasonably satisfied, I swapped the drivers for the second set, let 'em break in, yet ended up hearing a COMPLETELY different speaker! And these were supposedly darned nice SEAS drivers. But it is unfortunately very routine for transducer manufacturers to sell tight middle of the curve to large buyers, and then dump the outliers into the hobbyist market! Unless you're prepared to buy several thousand drivers OR spend megabucks for custom configurations you'll not be able to purchase close-tolerance pairs. Snell, Boston Acoustic, et al have great QA on the sensitivity and response of their raw drivers--unfortunately they can't voice a system successfully!--and I'm not sure you can buy their drivers. An engineer I know at BA thinks highly of their raw tweeters, for what it's worth. Maybe the pricier Dynaudio, Morel, etc drivers can be ordered as a matched pair...I'm not sure anymore....... It's interesting for me to note that Verity Audio chose to use a 1" thick granite slab in between their satellite/woofer base sandwich, with thin sorbo pads, as a coupler/energy-controller-dissipater. But making a box, especially with non-parallel walls, out of granite? Maybe you can find a good deal on diamond-tipped tools? Good luck, and let us know how it turns out. Happy holidays.

Thanks all for your input. I think I will scrap the idea of using granite for the enclosures. The properties that make granite the ideal choice for speaker enclosures also make it the most difficult to mill and fabricate inexpensively. I have some theil drivers and will try to duplicate a set of cs 3.6's out of MDF.

Suburuguru, sounds like you are an actual speaker hobbyist. To me, it's like being in R&D. Even the best around have a 95%(at least) failure rate. Yes, it is a wonderful hobby. But, no matter what you do, you gain experience and knowledge from it(the most important tools in this hobby). There is no perfect speaker, and it will not be coming in the near future. But, IT SURE IS FUN(and frustrating) chasing the Holy Grail. Gmkowal, I think your using MDF for your first speaker is a wise move. Look at your first project as more of a learning experience, rather than building a masterpiece. You may want to invest in cheaper parts for this go around, or build from a kit. If you feel comfortable in this area(or come to the conclusion that you should employ the work of a cabinet maker), on your next project look into multilayered enclosures(tons of directions to go in this area - the granite is interesting). Good luck! Please keep us posted, and don't hesitate to ask for advice.

Subaruguru is right on about the difficulties of working granite, only those with diamomd tipped tools need apply.MDF is just the opposite, cuts and routs absolutely clean with crisp edges and no tearout. Dimensionally stable so takes veneer extremely well. Knowing how it is made will tip you off to its qualities and popularity vis a vis particle board. Both are produced as "loaves" like bread but while particle board is pressed under 5000 lbs. pressure, 30,000 lbs. is used to compress MDF! You might try to find your local Wilson Art dealer as many fabricators are dropping the SSV (solid surface veneer) because of problems with fracture in use. SSV is an 1/8" thick sheet similar in look to Corian which is glued to a substrate (MDF). It could be cheap and works OK with ordinary carbide tools. Don't worry about the fracture problem as it only occurs in horizontal applications like countertops.