Hartley compound sub

[rdr]

For many years I have had 2 Hartley 24's in 20 cu. ft. enclosures and have been crossing them over at 150 Hz (active with their own amps). These have gotten to big for the room they are now in so I have put both Hartleys in one enclosure in series opposed, each driven by it's own amp out of phase (so called isobaric configuration) and crossed over at 80 Hz @48 dB octive slope. This is working out well and testing shows response flat to below 20 Hz.

I am attaching a picture but since this is the first time I have done thi s on this forum I hope it works

[moray james]

do you have T/S perameters for the hartley's. If the numbers were right you coul also consider a "W'" frame dipole configuration for the Hartley's as discribed by Linkwitz at his dipole sub page. This would end yp being smaller and you would have the output off of both drivers rather than the isobarik configuration where one driver is more or less sacrificed to drop the cabinet volume. A "W" frame dipole would not be much wider than 3x the driver depth (face of conre to back of magnet) and a bit larger than the diameter of the driver (cabinet height and depth). Might be worth a look. Drivers with Qts as low as 0.25 have been used in such designs but they will require some EQ. Regards Moray James.

[rdr]

I do not have them except for Fs which is reported to be 13 Hz. The restoring ring in the motor will certainly result in a low Qms. When I get a chance I'll measure them as I have the equipment. The Hartleys were intended for IB or even open baffle, but they will certainly work in a large saeled enclosure. They are now (as a compound pair) effectively working into 40 cu. ft. and effectively more than that because of the stuffing. I already have the enclosures and am kind of sceptical about open dipole baffles for bass anyway. The enclosure is braced 1" particle board, somewhat denser than MDF and weighs about 400 lbs.

[moray james]

there is a therad here on both ripole drivers as well as on H and U frame dipoles. Take a look at this EV patent # 4,733,749 on manifold woofer designs. You can also have a look at the last page of this thread, JBL 2268HPL as opossed to JBL2242H Regards Moray James.