I've seen lots and lots of talk on forums, people wanting to do a "skull-crushing" 3-way speaker; something akin to the Klipsch and Cerwin Vega "monkey coffins" of their wilder years. I was up for the task, but if I was going to do such a speaker, I wanted to meet a few additional criteria besides just being big and loud.
Here's a link to the build log I did along the way, for when you have a lot of extra reading time.
Finally, as for the tweeter, I pretty much had it in mind that I was going to use the Vifa/Peerless DX25. I'd used it recently in other designs, and learned its quirks. It's not the easiest tweeter to work with, but once you get it right, it sounds great. Also, for a dome tweeter, it can go extremely loud. (Slight update: over the years, the model number for this tweeter has changed from DX25TG09 to DX25TG59. The tweeter is almost the same, only the dome material changed slightly. The crossover only needed a slight adjustment for the 59 version of the tweeter. More below.)
When most people picture a loud, large speaker, they tend to think of a huge rectangular box--something shaped like a refrigerator, more or less. I have a big problem with this type of speaker, though: it's too heavy! Yes, I am a wimp, and I believe that most home audio speakers should be able to be moved by one person. (I used to work in pro sound and pro video. I did my time.) As a workaround to the heavy-rectangular-box problem, I separated the woofer from the tweeter and mid. To make this 2-part speaker more visually interesting, I started playing with using some angles on the cabs. I borrowed a few design cues from Wilson and VonSchweikert--nothing too dramatic, though. (After all, I was the one who was going to have to build it, and the tools in my garage are pretty basic.) The Tarkus can be built without the angles, if one chooses. The top cabinet would measure 13.25"H x 9"W x 11"D, and the bottom cabinet would measure 24.75"H x 13"W x 16.5"D.
The tweeter/mid enclosure is about 13 liters, sealed. It is filled with polyfil. The tweeter is flush-mounted, however the mid and woofer are both designed to be surface-mounted.
The woofer cabinet is 62 Liters, tuned to 30 Hz. I used a 4" dia piece of SCH 40 PVC that was 13.5" inches long. It just barely fits! I think one could get the same results using a 3" flared precision port, 8.5" long. The Woofer cabinet is lined with convoluted "eggcrate" foam, and does not have any stuffing or polyfil. The woofer cabinet will need a decent amount of bracing to tie the walls together, both from side-to-side and back-to-front. The TM cabinet will probably only need one simple brace; perhaps a piece of scrap 3" wide, tying the side walls together. Here are some graphs of the bass response, for those who like looking at graphs: Bass Frequency Response, Port Air Speed, and Cone Excursion.
Also, please note which version of the tweeter you have. When I originally designed the speaker, it was known as the DX25TG09-04. Over the years, they switched the supplier of the dome material, which changed the sensitivity very slightly. The new part number is DX25TG59-04. If you have the new tweeter, use the crossover on the left. If you have the older part, use this crossover. I apologize for the confusion.
Here is a Bill of Materials for the Tarkus from Parts Express. The drivers are all widely available throughout the US and internationally, so you shouldn't have much trouble procuring them. You can also shop around for crossover components; use whatever brand suits you. As long as the value is within 5-10%, you'll be fine.
Of course, if you DIY your own speakers, you can finish them any way you want. I'm still a hack woodworker, and finishing is still a very new arena to me. The finish I did on the Tarkus was definitely the best I've done yet, so I'm going to take a moment to show it off.
I built these speakers for my dad, for the "great room" at his vacation house. He loves Stickley furniture, so that was the finish I went for. I followed the mission oak instructions by Jeff Jewitt, for the most part. Some products weren't locally available, so I winged it here and there. But if memory serves me, it went something like this:
1. Apply veneer: Paper-backed Quarter-sawn White Oak
2. Stain: TransTint "medium brown" dye, mixed with water
3. Seal: 2 coats Minwax gloss wipe-on polyurethane
4. Glazing: Minwax "mahogany" gel stain
5. Topcoat: Minwax semi-flat polyurethane
6. Rub-out: steel wool and furniture wax
The results did look like Stickley! My dad and I were both quite shocked when we set the speakers next to his Stickley "Morris" chair, and the finishes appeared to be "cut from the same cloth."
The Tarkus were designed to play loud, play clean, and to bring rock recordings to life.
Rant on: Unlike classical and acoustic music, Rock recordings are not meant to emulate a concert hall. With rock, everything is close-mic'ed, sent through effects, and mixed at a console. It's a studio sound,
and it is what rock sounds like, and there should be no shame in that.
Furthermore, the production of rock music is part of the composition
itself. Consider for example the work of: George Martin (The Beatles), Brian Wilson (Beach Boys), Alan Parsons (Pink Floyd), Trent Reznor (Nine Inch Nails), Phil Spector, Ted Templeman (Van Halen), Terry Date (Pantera, Soundgarden), Mike Stone (Queen), Bob Rock (Metallica), David Bottrill (Tool, King Crimson), Rick Rubin, Andy Wallace (Nirvana, Jeff Buckley, Rage Against the Machine).... The list practically never ends.
And it's not just rock music that is so heavily influenced by its production. Other genres such as Country, Pop, R&B, and Hip Hop also rely on recording production as an integral part their sound, and the composition of the songs themselves. In some ways, it boggles my mind that more speakers aren't designed with this in mind. Rant off.
The Tarkus are indeed capable of producing the "pant-leg-shaking sensation" when cranked up past 100 dB. However, at more conservative listening levels, say 80-90 dB, I have found myself very surprised to hear depth and resolve in rock recordings I never would have imagined were there. Even at "quaint" levels of 70-80 dB, the Tarkus are still a lot of fun to listen to, and their ability to play low bass confidently still comes through. In fact, I think the thing I enjoyed the most from this design was the ability it gave me to differentiate the kick drum from the electric bass, and hear them separately--not sort of "mashed together" as is the norm on smaller speakers. (To explain further: kick drum is typically identified in a mix by the attack around 2-4 KHz. This way, you can hear it on any old speaker. What you typically do not hear on smaller speakers is the actual resonance of the kick drum, which is very low, anywhere from 100 Hz down to below 20 Hz, depending on the size of the drum and its tuning. You can rarely pick this out on a normal speaker because it gets mixed up with the electric bass (or is removed altogether by the mix engineer). The larger woofers in this design, however, let the two coexist, which I really enjoyed, being a drummer and all)
So enough talk. Guys have been clamoring for something bold and loud, and this is my contribution. Forget the Telarc, Mapleshade, and Sheffield Labs CDs--these speakers are for the rest of your collection! (You know, the stuff you'd rather be listening to.)
The first person (to my knowledge) to tackle the Tarkus was [bolland83] from the Parts Express board. In the style of good ol' rock n' roll, he did a faux sunburst finish that left a lasting impression on the PE board members. His build threads are here and here.
[cowtown] of the Parts Express board had the idea to do the Tarkus in a 1-piece curved cabinet. He took on many new challenges in the project, but the final result was a glowing success. His build thread is here, which does a good job of explaining each step of the process.
This is a pair crafted by Dave G in cherry veneer.
Finally, this is a completely different speaker design, but it deserves some mention. It was done by Parts Express employee mattp, who liked the looks of the Tarkus that he um... borrowed from it, liberally. His design uses some exclusive, pricey HiVi drivers. More info here.
This build was done by Steve in a speaker-building frenzy of sorts. (you may notice he built a pair of Overnight Sensation TM and MTM in the background). The color and woodgrain is really striking.
Gabe did a handsome pair with a contrasting paint/veneer scheme.
I love this interpretation by Per. He decided to gently taper the whole cabinet. The white finish just sets it over the top, and it looks like something that should cost 5 figures.
And while your jaw is on the floor, take a look at Eric's interpretation. The curved back is beautiful.
[Mr Ed] "veneered" his Tarkus with strips of Cherry. Quite a painstaking process. The build thread is here.
This is beginning to make me feel very inadequate as a woodworker. Here is Wes' Tarkus. Build thread here.
Speedle took the Wilson look to the extreme on his. Gorgeous painted finish, too! Lots more details in his build thread here.
[Snmhanson] has some fabulous cabinet and veneer work going on. For details on how he build these, go here.