This is probably the first pair of OB12 drivers made. Nick, John and I were discussing dipole woofers in a thread on a different forum, when John suggested they could build something based off the IB15 design, but 12", with a softer dustcap and different cone treatment that made it more suitable for dipole use. I've built 3 different speakers with these, and they are amazing drivers, as you'd expect. I've usually crossed over to a sub around 60-80Hz, you can go lower if you use a wider baffle. On the other side, I've crossed to a midrange between 250-500Hz.
I have 2 kids now, and no time for DIY. These have been sitting in my garage for several months, and I've finally decided to let them go, because it will be many years before I get back into this hobby.
The drivers are in great shape. They've been in a non-smoking pet-free environment, and driven with proper amplification (mostly Emotiva). There is one cosmetic blemish - one time when I was measuring my speakers, my toddler bumped into the mic stand and toppled it. It scraped the driver on the way down (see photo). This didn't cause any audible or measurable difference that I could tell. The white marks on the surrounds are dust, the surrounds are fine.
$150 OBO + shipping.
T/S parameters and frequency response measured by John:
Fs: 28hz
Qms: 4.36
Vas: 129L
Cms: .35mm/N
Mms: 94g
Rms: 3.8
Xmax: 18mm
Xmech: 20mm
Sd: 510sqcm
Qes: .53
Re: 5.5 ohm
Le: .3mH
Z: 8ohm
Bl: 12.9
Qts: .47
1wspl: 89.2dB
2.83V: 91dB
