Here's the latest motor from Adire Audio - the Parthenon Motor (named such for obvious reasons). Set up with the same dimensions as a Tumult, this unit can work with a dual wound coil to realize over 80mm one way linear stroke. Oh yeah - flux in the gaps is pretty high, at 0.8T - the 3" diameter core (with a SMALL 0.75" diameter pole vent) is completely saturated - that's a LOT of flux in there! Here's the motor sitting on the bench. It's made from 1008 grade steel, and uses 16 N38 grade neo magnets. The back plate, and both gap plates are flat discs. We use 8 columns to space the lower gap plate up, and 8 columns to space the upper gap plate. Each column is capped with a neo ring - those are the magnets for the system. The lighter colored tops on each column are the neo magnets. Here's another, more "side on" view. You can see the inner gap plate quite nicely in this picture. All suspended by nice columns. Definitely a trick looking motor. Gap plates are 0.5" thick, back plate is 0.75" thick. Columns are 7/8" diameter. Overall diameter is 8.75", and it's 7.125" tall. Yes, it's deep, but when you consider it has a clean 7" of linear stroke, well, you understand where that height comes from! Another view, but from above. You can see the nice brass screws used to assemble the motor. Gotta use non-magnetic screws, and the brass looks really nice on the steel. View from behind. LOTS of screws holding that thing together! Sixteen total columns, each with a screw at each end. And the pole is held in with 4 more screws - a total of 36 screws. These aren't small screws, either - 1/4"x20 bolts. And last but not least, one more sideways shot with the motor on its side. Ever seen a loudspeaker motor you can look through? I didn't think so... So how are we using this? Well, for starters with double-stacked dual voice coils (we'll diagram that out later). Basically four 2 Ohm voice coils in this beast. These motors are semi-stock items. We have parts to build several up in stock, but don't actually build them until they are ordered. Voice coil configurations, diaphragms, suspensions, all those are full custom units, so you can spec out what you ideally want. At the 2004 CES we'll be showing a 24" square baffle unit, with a Qts of 0.72 and an Fs of 7 Hz. Flat anechoic response to 6 Hz. And capable of over 66 liters of linear air displacement! That will generate reference level (121 dB SPL) output at 20 Hz, when sitting naked in a room - no room gain, no baffle, no box required. The first true dipole driver (not sub - no baffle, remember!) that can do reference outputs. With flat output to the single digits. How's that for a driver? Price? Well, if you gotta ask... Basic charge for the motor will be in the $2500-$3000 range, and that includes a base suspension (there's a LOT of machining in this piece, not to mention the price of the steel or the neo). Final cost depends upon the application - diaphragm size, voice coil config, any changes required (note that it's trivially easy to add more stroke - lengthen the voice coils, use taller columns, and we're there), finishes (powder coat, anodizations, paint, etc) will all affect the total price; figure in the $4500-$5000 range for most "normal" application. But considering what you have here - more output than 12 Tumults in the base 2004 CES trim! - it's a relative bargain. So how far can you go? A 48" x 48" panel would be about the limit. Pretty easy to stretch the motor to 12" of peak-to-peak stroke, so that would be around 16 cubic FEET of displacement (over 450 liters of linear displacement). Now THAT would be a monster! Anyone game? I know a few famous car audio names who are already planning to use this beast, want to join that exclusive club? Hmmm... An IB with one of these units might just be the trick for a new 100 seat theater, too... Anyone out there building a big home theater?