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Introducing my new "Ultimate 1.1" subwoofer

I've replaced the dual stacked subwoofers with my new build using a 21" XBL^2 motor design by Dan Wiggins with Acoustical Development and sold by Kevin Haskins at DiyCable.com. This 50 lb beast is called the Maelstrom 21.

What a terrific subwoofer! In addition to this large coned driver, I've added 4 - 18" flat MDF passive radiators that I've loaded to 2100 grams of mass each. With these massive passive radiators mounted opposing each other, and the heavy weight of the 1.25" thick MDF cabinet, this subwoofer is as stable as can be. I've posted some build pictures at the bottom of this page showing my unique "front to back" upper and lower internal bracing, and with the material being this thick, I hear no resonance at all.

I installed Sonic Barrier panels on the top and bottom of the cabinet to absorb any possible resonance and standing waves. In the upper section of this subwoofer, I stretched audio grade grill cloth very tight for a porous "bag" and filled it with a polyfill product. After completing the build, I added more polyfill in the bottom just before securing the last bottom passive radiator.

Of all of the subwoofers I've ever built or auditioned, I've never heard one get so low and clean. Even at low volumes, especially highlighting the LFE sound effects the movie directors put in their movies, you can feel bass that has never been felt before by a conventional sub. It is adjustable using the Reckhorn B-1 to keep the wife happy. It is also very, very musical as well.

The size is 23" x 23" x 62" tall, 13 cu. ft. internal cabinet size, and has a box tuning frequency of 15 hz, but it goes much lower than that.

Fs: 16.3 Hz
Le: 4.0mH
Re: 3.8 Ohms (Voice Coils wired in series)
Qms: 3.38
Qes: .44
Qts: 0.42
Mms: 527g
Cms: 0.18 mm/N
Vas: 605L
Sd: 1550 cm^2
BL: 21.5
X-max: 32mm
Pmax: 1500W
SPL: 89.6 db/1W/1M

Below is a photo of my bass management control. I have a single Face Audio TS1200 bridged to mono amplifier, that can provide 2719 watts of power at 4 ohms to the subwoofer. This particular amplifier is strong on the low end as well. It weighs just over 50 lbs. I did add two extra dedicated electrical circuits for my home theater equipment. I am also running a pair of Panamax line conditioners with line voltage protection to cover all of my HT gear.

Now, check out my Reckhorn B-1 subwoofer control below. Just look at all of the features this little, and quite heavy box has to offer. It also includes a high pass filter. It is German built and is a finely machined work of art. The controls feel like they are very high quality!

Home audio receivers and processors usually have a low impedance subwoofer audio output, and the professional amps like I'm using require a high impedance input. The Reckhorn B-1 equalizer bridges the gap between home and professional audio equipment and allows you to shut off all of the limiters of the amps as it takes over full management of your subwoofer. With the amplifier's limiters and protection switches turned on, you are losing a lot of the bass your amplifier is capable of producing. This is a "must have product" if you are running pro or conventional audio amplifiers and want to get the output that your amp is capable of producing.

I like the professional amplifiers because they don't have the really loud "punchy" or bass boost that most plate amplifiers have to use to get you the output in wattage you need to drive your subs when the music levels go up. IMHO, plate amps really have to strain to get their peak rms power out to your subwoofer. My subwoofer has a very distinct, clean, and smooth bass sound without all of that punching. If you are watching a movie with explosions or deep bass like can be found in U15, Armageddon, or Jurassic Park movies, it will indeed scare the heck out of you and are so lifelike!

The passive radiator design really adds a lot to the quality bass I am getting out of my subwoofer and have their own unique sound. I've posted a link in the above paragraph to give you a better understanding of how and why they sound better than a ported or sealed sub. Many audiophiles will argue with me about the use of the passive radiators just like a Chevy or Ford owner will exchange words, but I've had a lot of experience with both. A sealed subwoofer is less efficient and requires more power to drive them, and the ported subwoofer is subject to port chuffing, noise, and port resonance. Most of the port happy subwoofer owners have never really heard a well built and designed passive radiator subwoofer. One of the few and most heard reasons not to use a passive radiator subwoofer is that when they reach their tuning frequency of the cabinet, the bass rolls off quicker than a ported sub. Well, if you have a passive subwoofer tuned to 15hz, and you start rolling off faster than a ported sub, your sub will go below the frequencies that your ears can hear anyway. Below is the Reckhorn B-1 equalizer I use for my bass management.

Reckhorn B-1 bass management

Lets talk music. Joe Satriani's bass player has two pairs of stacked quad bass speakers on each side of the sound stage and when I crank it up, it sounds like they are on each side of my living room. The same thing applies to the Crossroads album performed at the Rice Stadium in Fort Worth a few years ago. This was Eric Clapton's benefit for his Crossroads drug and alcohol recovery center in Antigua. It is a twin pack DVD with an endless list of some of the finest musicians and superior audio editing I've ever heard. There is a lot of blues and rock and I crank it up. It is my favorite music DVD due to the quality of the recording and the list of performers like Buddy Guy, BB King, Joe Walsh, James Taylor, and on and on.

I also listen to music from Yanni, Michael Murray SACDs of organ music , Fredric Fennel's march music with the Philadelphia Symphonic Orchestra SACD, Diana Krall, and other quality performers. You don't have to crank it up to enjoy it. When a bass string is plucked, you look around for the player and his amp. Kettle drums in march music by an orchestra can scare you if you don't know it's coming because it sounds so real. Take a full stand up bass that Diana Krall's bass player uses and watch him drag his bow string across the strings. It's like you had your ear up next to the piece of equipment. This wonderful sub is the Ultimate 1.1