Those who know me know that I'm always on the lookout for good, cheap 12" drivers for car audio and other duty. 12" drivers seem to hit the sweet spot of size and performance, and because of the high costs of shipping and duties, it's important to me that the cost be kept as low as possible.
My 12" drivers I'm currently using in my car for car audio duty are Infinity 122.7Ws, which offered the best value back when I purchased them for about US$100 each . Even better, they are neo-magnet drivers, so the weight (and therefore any associated shipping costs) of each 122.7W was pretty low when compared to similar drivers. Unfortunately, the surrounds started separating from the cones a few weeks ago, and with my birthday coming up, I thought it was good time to replace them (SWMBO - "new subs, AGAIN?" Me - "but it's my birthday!").
After perusing the technical specs of several brands, I eventually decided on the Alpine Type R 12D2s. They were in third position on my "displacement/$" list (the top rung on the list is occupied by another Alpine driver, btw), but offered the most linear displacement (Sd*Xmax) of the group. I would have preferred to go with a neo-magnet driver again (for the reasons previously stated - one of these 12D2s weighs twice as much as a 122.7W, with some change left over), but it seems no-one really has a suitable one on the market these days, likely due to the current high costs of manufacturing these magnets. I also chose the 12D2 rather than the 12D4 because two of them will provide a 2-ohm load to my subwoofer amplifier, an Alpine PDX-M12.
I received the 12D2s two days ago, and ran them through a few tests. Measured t/s parameters are quite close to the published specs (close enough so you can use the published specs in any computer-based box design program). Well, except for Le, which my WT3 put at 3.1 mH, quite a bit higher than the quoted 2.23 mH for this driver. It's a bit high for a driver that has a shorting ring, so I'm a bit curious as to why that's the case.
Concerning physical attributes, the 12D2 is pretty solidly built, with a very, very stiff cone structure and a suspension, while it appears to consist of a just a single spider and the "HAMR" surround, appears to me to be firm enough for the driver's intended purpose. Motor noise was also pretty low during the low-frequency "break-in" I did before performing the t/s parameter tests, another good sign (for the record, I'm not a believer in having to "break-in" a subwoofer, but doing so costs nothing and avoids getting into any arguments afterwards with the believers about proper break-in before testing, LOL). Other physical attributes worth mentioning are the basket structure, which appears to be very sturdy but unfortunately does not offer any visibility of what's going on below the spider, and the rubber trim ring, which is made of two parts, both of which are removable.
In my next post, I'll include some comparison measurements (impedance, frequency response, distortion) with the 12D2s mounted in my existing car audio subwoofer enclosure and then finally some listening tests.