Drivers ListAlpine DriversSWR-1522D

Motor TypeOverhung
Driver Size15 "
Driver Weight30 lbs
Coil Diameter2.5 "
Coil MaterialAL
Coil Length2.02 "
Gap Height0.3937 "
Manufacture's Xmax20.5 mm
Geometric Xmax20.7 mm

TS Parameters (Measured by

Fs26.7 Hz
Res3.2 Ω
Le 1khz2.48 mH
Sd0.0775 m2
Vas72.9 liters
Mms408.8 grams
Cms87 μm/N
BL21.37 Tm
BL2/Res142.7 N2/W
L/R Time Constant0.77 milliseconds
SplSens86.44 dB


The Alpine SWR-1522D and the companion dual 4 ohm version, is currently the largest driver that Alpine makes and it has been in the lineup as is for a number of years. This is a dual 2 ohm 15" driver with a number of quality features not typically found on drivers that can be had for about $200.

The SWR-15 is built on a large proprietary cast aluminum frame, which is quite robust and features a set of vents built into the spokes for venting under the spider. The motor is a moderate size and is based on 2 slugs of ferrite that weigh 155oz. The back plate has no pole vent or bump out and no under gap vents either. All venting appears to come through the aforementioned vents in the frame itself. Alpine is quite generous with specifications and details on all of their drivers so it is known that the top plate is a 10mm thickness and the voice coil is a 51mm wind height. That gives a generic coil overhang of 20.5mm which is the rated Xmax for the driver. Alpine also lists an Xmag of 21.5mm. Xmech is given as 35mm. The motor geometry indicates that the coil would leave the gap at about 30-31mm excursion so it would be operating on fringe field beyond that point. To finish rounding out the voice coil specs it is a 2.5" nominal diameter, 4 layer aluminum wind on an aluminum former. The cone is a kevlar reinforced /pulp fiber (paper) with a large inverted dish covering the entire front of the cone for reinforcement. The spiders are a pair of nomex, progressive rolls that are roughly 9" in diameter. The spiders are also mirrored to help lower distortion. The surround is santoprene rubber with an unusual multi roll profile. Alpine apparently has a patent on this type of surround and calls it a HAMR or high amplitude multi-roll surround. Alpine put a significant amount of R&D into it and it seems to work quite well. There is also a molded rubber trim ring to cover up the screw heads and edge of the frame. The motor even has a shorting ring/cooling system employed. The terminals are typical spring loaded types but are arranged on the same side of the frame which is convenient. As is typical of most car audio drivers the SWR-15 has a large, red Type R Alpine logo on both the cone and back of the motor.

Running the SWR-15 in free air showed that it is quiet in operation and doesn't start to make obvious distortion or mechanical noises until driven well past xmax. The parameters pulled from the driver are fairly close to the Alpine specs. The notable exception is the Fs which comes in a bit higher at just under 27Hz due to a lower suspension compliance. This in turn modifies things like the Vas and Qts but after a bit of break in the suspension will loosen up over time and these should edge closer to the manufacturer specs. Once that happens the two data sets will line up well. Looking at the impedance measurements they clearly show the effects of the shorting ring system, with a very gentle rise towards 1kHz rather than a precipitous uphill climb as seen with most bass drivers with extended xmax capabilities. The inductance at 1kHz measured 2.48mH which is almost dead on to the Alpine spec of 2.53mH.

The SWR-15 a solid driver which offers a lot of performance and the amount of R&D and Klippel testing during development that Alpine has done really shows in this driver. Specifically it juggles the tradeoffs of long excursion, power handling and low distortion in a compelling way considering the street price which can sometimes dip near $200.

Alpine 15" SWR-1522D Systems