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All this happened, more or less.
For many, many years, I have wanted to design an authoritative TMWW tower, but the stars never quite aligned. I did do a variation on the Swope many moons ago that could be built as a TMWW tower, but it wasn't purpose-built from the ground up to be one.
So I stowed the idea away for a large TMWW in the back of my mind, always keeping a lookout for a range of reasonably-priced woofers that would work well in that configuration. I did try a few as prototypes over the years, and the results were always OK... but never was I really sure that what I had was worth continuing further. A big breakthrough happened when Erich at Cinergy told me about a series of woofers he had created to match the look of the S2000 woofers; and wouldn't you know it, but he'd gotten them in 7" and 8" sizes! Of course the real proof would be in how they measured--and lucky me, the T/S specs and Frequency Response were a great fit for the kind of design I'd always wanted to do!
Now, in order to really do this project right, I didn't want to just design some TMWW towers. I wanted to design a family of speakers:
TMWW towers. The flagships of the series.
TMs that would work as a vented floorstander or sealed bookshelf.
A monster Center Channel to for those who want to build it into a killer home theater.
Needless to say, this project--or rather, a series of projects--has been a long time in the making. But after years of iterations and tweaking, we have finally arrived. I present to you the Leviathan series.
Driver Choices
As I was saying earlier, I'd toyed with a lot of various woofers over the years in the pursuit of this project. The obvious choice would have been the Dayton RS series--however there already are many successful TMWW designs for the RS series out there--and have been for 20 years! Naw, I needed to find something new. I wanted woofers that:
Came is a variety of sizes from 5-8 inches
Could play deep bass in a vented enclosure
Look cool, and have a reasonably-good build quality
Don't cost a small fortune (this design needs a lot of woofers, after all)
And wouldn't you know it, but Erich had just the woofers, waiting for just the right project. He calls them the Carbonite series!
Denovo Audio WCF220-8
The WCF220 features an 8" woven carbon fiber cone, vented pole piece, cast aluminum frame, and an impressive 7.5 mm of xmax. It is well-suited to bass duty in a speaker like this. Build quality and materials are top-notch.
Denovo WCF180-4
The WCF180 is the slightly-smaller sibling to the WCF180, and features a 7" woven carbon fiber cone. It's frequency response is relatively well-behaved, and pretty easy to work with overall. I chose the 4 Ohm variant to ensure that I would have enough headroom to keep up in the pair of 8" woofers.
XP Audio Tweeters
Wait a second: what the hell is XP Audio? It's me! I'm XP Audio. Bet you didn't know I sold tweeters? Well, I do now! Pretty cool, eh? I'll save you the backstory, but suffice it to say, I'm very pleased to be offering these two tweeters to the DIY speaker community. They both are well-suited to the Leviathan series. So I will be offering the builder a choice: a typical textile dome, or a more exotic planar.
XP Audio TD-25N
The TD-25N is a textile dome tweeter with a neodymium magnet. It has a lovely Frequency Response, is low distortion, and can be crossed easily at 2 KHz. It comes with a thick aluminum faceplate in my favorite diameter: 104mm.
XP Audio TR-52P
For those who like something a bit more exotic, we have the TR-52P, which is a magnetic planar ribbon tweeter. It harkens back to the Bohlender-Graebner Neo3 (for those old enough to remember) in terms of looks and ease of use. However, I'd argue that it's less "mellow" sounding than the old Neo3, and instead has a bit more of a ribbon sparkle and snap to it. Very fun little guy.
Enclosure Design
Like I said before, I have always wanted to design a TMWW from a clean sheet. In my mind, a TMWW tower ought to be able to handle anything and everything you can possibly throw at it, from Classical to Rock to Jazz to EDM to Gaming to Home Theater, all while giving you the option of not turning a subwoofer on. An everything speaker. (In car terms, it's the daily driver that's also a sports car that also has the ability to go on dirt roads once in a while) Is that impossible? Perhaps, although after hearing a certain commercial speaker that I will not name directly--but whose name rhymes with "Bevel Conforma"--I knew I at least had a target I could shoot for.
So when designing the enclosure, I paid a lot of attention to what I liked and disliked about currently-available large floorstanders on the market. The result is me taking all the parts I liked about various ones, and mashing them up into something that would make a presence in my living room, and that didn't weigh a million pounds, and could be built with modest DIY tools or flat packs.
The overall enclosure is a large rectangular prism, most of which is airspace for the dual 8" woofers. Subtracting the sealed inner chamber for the mids, the woofers have about 68 Liters to play in. The enclosure uses a 3" dia port that is 3" long. This tunes the enclosure to 38 Hz, and will get a -3 dB point around 36 Hz. The woofer chamber doesn't need much damping; a few sheets of eggcrate foam should be fine.
The upper chamber, which houses the mid and tweeter, should be sealed off from the rest of the cabinet using caulk. I would recommend stuffing it amply with polyfil or similar dacron stuffing.
I used 3/4" stock all around, but if you wanted to get fancy and do a thicker baffle, you are certainly free to do so. The woofer cabinet needs bracing; mine uses some strips of wood, 3-4" wide, tying the sides together.
Crossover Design
The crossover is not too bad. For starters, I kept the mids and woofer filters exactly the same regardless of which tweeter you choose, so let's start by discussing those first.
The woofer filter is a 2nd order, with capacitor C5 acting as a "tank" filter.
The mids filter is a 1st order highpass, and a 2nd order lowpass. Then there is an L-Pad (R3+R4) to attenuate its level slightly. Finally, I used an LCR filter (C4+L3+R5) to contour the Frequency Response of the mids to my liking.
Finally, for the tweeter filters. In case it isn't obvious, the dome tweeter needs a different filter than the planar ribbon. The TD25 uses a 2nd order filter, where the TR52 I used a 3rd order filter in order to play with phase coherence a bit.
Frequency Response
The Frequency Response of the Leviathan TMWW is quite linear. As I said, I was really aiming for an "everything speaker." The woofers cross over to the mids in the low 400 Hz range, and the mids cross to the tweeter around 2500 Hz. As usual, ignore the measured response below 200 Hz, because I use gated MLS.
Impedance
In spite of everything, I don't really think this speaker presents a very challenging load. Sure, it dips below 5 Ohms in a few spots, but so do a lot of commercially-available "8 Ohms" speakers. Regardless, do these a favor, and run them with a good amp. C'mon, these are flagship speakers here! Feed them good stuff!
Listening Impressions
All right, so we've gotten all the nitty-gritty taken care of. How do they sound? They sound massive, just like I always wanted. Like I said, a speaker this size shouldn't need a sub if I don't feel like it. For pretty much all the music I listen to, they play all the way down, nothing gets missed. The only time I'd really feel inclined to use a sub is if I was watching a movie with a lot of Low Frequency Effects.
When I was voicing the crossovers, I spent a lot of time sweating the "loudness" of these--for lack of a better term (ie: that "loudness" knob or button on some stereos). What I didn't necessarily want was a speaker that sounded OK at low volumes, but then really came to life as you cranked the volume knob higher and higher. No, I wanted a speaker that sounded "big" even at quiet volumes. Because let's face it, a lot of the time that's all I can get away with in my house--and I'm sure I'm not alone in this. So I scrapped several crossovers along the way in search of this goal. To finally get there, I did have to sacrifice a few dB in Baffle Step Compensation, so these aren't quite as sensitive as they could be. Still, I'd estimate that they're around 87-88 dB efficient; certainly nothing to sneeze at. The payoff is worth it, though. Because, like I said, these sound huge at all volumes, and they sort of "envelop" you in sound. And really, that's what it's all about for me.
The Leviathan TMWW can get quite loud, though. With a robust 100 Watt amp, they should be able to hit 112 dB before you run out of xmax.
As for the differences in the tweeters, I'll describe it this way. The TD25 I treated like I do most dome tweeters, and was able to get the sort of pinpoint imaging I love to do. The TR52 has a bit more "air" and thus opens the soundstage up somewhat. I'll leave it at that for now, and your own personal preference.
I chose the name Leviathan because designing these speakers (and the rest of this series) was somewhat of a White Whale for me. It was a long, sometimes difficult process with lots of ups and downs, but I just couldn't get it out of my mind until I'd finally slayed it. Unlike Ahab, though, accomplishing the task didn't kill me! I kid. But seriously, what I believe it's done is start a new chapter in my adventure as a designer; one where I can control more aspects of the drivers, and work closer with you, the builders and music lovers. Enjoy!
by Paul Carmody | this page was last updated August 11, 2026
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