Speaker Enclosures

I have recently come into some granite counter top material(A neighbor is in the remodeling business and offered it to me). Has anyone had any success trying to make speaker enclosures out of this stuff? I have enough to make two medium enclosures but have no clue if it is even feasible to attempt. If any of you DIY'ers out there have any info I would appreciate it before I bite off more than I can chew.
I think it´s good to combine it with another material, such as MDF.Will use this combination myself. Regards Håkan
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.
Gents, once again, great responses! My first love is wookworking, then audio. Now that the kids are gone, both woodworking and audio keep me busy in my spare time. I initially thought of copying the Theil 3.6's because I have some Theil drivers that I am not using from an old pair of 3.5's, but on second thought I will take your advice and purchase a crossover and driver kit and build the enclosure. You guys have given me sound advice and I am afraid I will have to tap your collective minds one more time. I have heard that you can purchase drivers and crossovers as a kit with plans for the enclosure. Does anyone have any recommendations? Thank you all in advance.
Gmkowal it's great to hear that you are jumping into our hobby! You are many steps ahead of most of us(me included) in that you are a woodworker. As far as kits go, you have a lot of options. Check out Orca Design's(orcadesign.com) website for some great information. Make sure to request literature from them, as when I have gone there, the designs were nowhere near as numerous as what they used to send me through the mail. Kimon Bellas(GREAT guy) runs the show, and they are the US parts division of JMLabs. Have excellent drivers from Focal, Cabasse, Vieta, Raven, etc. They used to regularly send me a pack of information as thick as a phone book loaded with advice, designs, kits, and parts. The big contributors in this information(in addition to Kimon) were Joe D'Appolito(EVERYBODY uses his designs), Dick Olsher, and the folks from Focal and Cabasse. Next to try is Madisound, they have parts and kits from everywhere. Kits are good for a novice, but you will find the sound quality lacking once you become more advanced. But, Madisound will always remain a resource for you for their parts(real good prices). Check out North Creek design for their excellent ideas on putting together cabinet walls. Their coils(12, 10, & 8 gauge!) are some of the best you can buy. They turned me on to Ohmite wirewound resistors. Take it from me, there is no more cost effective way to improved sound than wirewound resistors. Alpha Core Goertz(same people who make cable) also have nice coils(including silver), but the sound is much different than North Creek's(more forward, less relaxed and sunny). Best large value caps come from SCR, same company as Solen. SCR's sound much better though(use better film and foil). Smaller value caps can come from Wonder, Hovland, or MIT/Rel(my favorite). Get wire from Orca or HomeGrown Audio. And finally, Zalytron is a great resource(assuming you are not put off by Elliot's demeanor). He has as much "real world" knowledge as anyone. You can show him something that looks great on paper, and he'll tell you to forget it. He will then change your crossover values to numbers that don't jive with any chart around. 99% of the time he is right. You'll get excellent crossover designs from either Elliot or Kimon.
Gmkowal: If you have considered trying out SET amps in your system you may want to take a look at the Hammer speaker kit @ hammerdynamics.com - there are also some user reviews at Audio Asylum under the high efficiency speaker section. You can buy moderatley efficient speakers all day long but usually pay a high premium for super high efficiency speakers. They are not a horn design and look very interesting IMO.
Wow! You guys are unbelieveable! I did not expect to get so much good info, so fast. I will be checking out the site that you all graciously pointed out. I have two systems at home. I have an old Threslold Stasis amp in one and an Aleph 5 in the other. The Threshold drives a pair of Theil 3.5's and the Aleph drives an old pair of Advents left over from my GAS system purchased in the late 70's. Uh-Oh, my age is showing. The Advents are not terribly sensitive (89db) and are in real need of replacement so the practical decision is to purchase a Kit and build the enclosures. I have some book matched birds-eye maple veineer that I was saving for a rainy day so as soon a I select the kit it's off to the lumber yard. I am really excited to get started and wish to thank each and every one of you for pointing me in the right direction. PS: I have been out of engineering school for 30 years. Anyone recommend a good filter theory book for me to brush up with. These days, I can only count up to one if ya catch my drift :-) Thanks again Gents!