Adire Audio Parthenon - Revisiting the Ultimate Subwoofer

Filed under: Home Audio > Subwoofers > Subwoofer Drivers



The recent increase in interest for really high-output subwoofers reminds me of a time when there was a clear winner in the Xmax competition. A single driver existed that could displace the same amount of air as thirteen JL Audio 13W7's. And if you've seen the CAD drawings of the upcoming Exodus Audio Sicko-X's motor, you probably thought the same thing I did: "Hello Parthenon, my old friend. I've come to talk with you again." If you haven't seen or heard of the Adire Audio Parthenon before, you need to hold onto your hat and read on about one of the most innovative and powerful subwoofers you'll ever see. And if you have heard of the Parthenon, I think you'll agree it's time for a re-visit.

The Parthenon is named after the famous Greek temple built for the goddess Athena. Known for its tremendous pillars of strength upon which the entire design is dependent. Like the famous temple, the Adire Audio Parthenon also has its own powerful columns in the motor design, which is really the heart of the Parthenon. The motor uses an upper and a lower top plate that are spaced to maximize linear BL over a large stroke, achieved with a combination of both the Split Coil motor topology and Adire Audio's own patented XBL^2 approach. In a basic sense, each coil has its own gap that it rides in. As coil A begins to leave gap A, an equal number of windings from coil B enters gap A. This keeps BL linear over quite a wide stroke. How much stroke you ask? Well, although the motor was customizable for more or less Xmax (dependent on your application), it comes with an astounding 72mm of one-way Xmax as derived via the 70% BL method of measurement.

Just to give you an idea of what this motor can do...


As already mentioned, the use of columns is a key to the success of the Parthenon. There are 8 columns between the back plate and the lower top plate, and 8 columns between the back plate and the upper top plate. Each column has a N38 grade neodymium ring on top, which is what provides flux in the motor. Each of the columns are 7/8" in diameter, fitting into an overall package that is 8.75" in diameter and 7.125" deep. And with all this stroke it tips the scales at a relatively modest 46 lbs; thank goodness for neodymium!



Of course, the motor is of little or no use if you don't have a suspension to support it, which is where the Parthenon gets really interesting with the patent pending Arachnid suspension system. Rather than the standard cloth suspension you see in most systems, the Parthenon used a very innovative metal suspension with spirals of metal that are easily swapped to change compliance, function as integrated tinsel leads to avoid tinsel slap, can be swapped if the metal fatigues, and supports stroke in the rearward direction of up to 140mm! To help offset the onset of stiction, the pole piece was heatshrunk with Teflon. The front of the pole has a Delrin slider bearing designed to help provide smooth, non-sagging stroke. Honestly, I have seen a lot of motors of different geometries and approaches, but I have never seen a suspension like the one on the Parthenon.



The Parthenon also uses a different approach to a "cone." It uses a replaceable panel on the front that can be adjusted to your application. A 48" x 48" panel (think dinner table) could be fitted to the Parthenon to increase surface area, and if the motor were adjusted to support 12" of peak-to-peak stroke, you would net over 16 cubic feet of displacement.

Does it work in real life? Absolutely. A 53L of displacement version of this driver is capable of can produce more than 120 dB of SPL from 11 Hz and up if you've got an anechoic room for it. When measured at CES 2004, over 134 dB SPL was produced at 11 Hz! Unbelievable. Designed for use in infinite baffle and dipole applications, you could really shake a theater with this thing.

Of course, it wasn't cheap either. The basic charge for the motor was $3000. The final cost was dependent on your application, but could range anywhere from $5000-$8000. A minimum non-refundable deposit of $1500 was required just to get the 10-12 week design process started. The end result was sheer magic.

Sadly, the Parthenon is not available commercially as far as we know and Adire Audio is now defunct. There were just three Parthenons ever made: one is now with its creator, one is with a client that builds military accelerometers, and one is in a client's dipole subwoofer. However, the brains behind the Parthenon is the international man of mystery known as Dan Wiggins (now of Acoustic Development International) who has a hand in the upcoming Sicko-X, an apple that doesn't seem to have fallen far from the tree and is targeted at a much more affordable price range. Incredible visceral output is within our reach.

Here are the Thiele/Small parameters of the Parthenon that was used at CES 2004.

Fs: 11 Hz
Qms: 19.4
Qes: 0.73
Qts: 0.70
Vas: 4560L
Sd: 3716 cm^2 (24" square)
Xmax: 72mm one way BL linear
Xmech: 140mm rearward one way
SPL: 91 dB @ 1W, 1m
Impedance: quad 4 Ohm voice coil
Cms: 0.24 mm/N
BL: 30.5 N/A
Re: 11.2 Ohms (all voice coils in series)
Mms: 880 grams
Vd: 53 liters
Pmax: 2000W total

A big thanks to Dan Wiggins of ADI for providing the information and images.