Drivers ListStereo Integrity DriversHST-18 Ver2 (2015)

ManufactureStereo Integrity
Motor TypeOverhung
Driver Size18 "
Driver Weight70 lbs
Coil Diameter3 "
Coil MaterialAL
Manufacture's Xmax35 mm

TS Parameters (Measured by

Fs16.9 Hz
Res3.8 Ω
Le 1khz4.21 mH
Sd0.115 m2
Vas311.9 liters
Mms527.8 grams
Cms169 μm/N
BL24.2 Tm
BL2/Res154.2 N2/W
L/R Time Constant1.11 milliseconds
SplSens87.99 dB


This is the dual 2 ohm 2015 version of the Stereo Integrity HST-18. Overall the performance and build of the driver are very close to the original version but with a few notable changes. The surround seems to be slightly different and perhaps just a bit heavier thickness of material. The back plate on the motor now features a total of 16 under gap vents instead of the 6 larger vents that were on the original driver. The spacer between the motor and frame which provides clearance for larger voice coil incursions and allows venting under the spiders has also been changed from a single piece to a a set of round aluminum spacers. The pole cap shorting ring system in the motor is also said to have been revised slightly. There have also been some changes to the voice coil judging by the slightly increased resistance and increased moving mass.

The result of these changes is slightly increased moving mass as mentioned previously, slightly more motor force to offset the increased mass, a bit softer suspension compliance resulting in a very low Fs of a little under 17Hz. The increased venting in the motor and new coil should help the power handling just a bit as well. The Xmax and most other parameters remain unchanged or close enough not to matter.

The parameters pulled from this driver are rather close to those provided on the Stereo Integrity webpage. Fs and Vas are close as is the 1kHz Le rating and coil Dcr. Qts, Qms and Qes are all well within reasonable tolerance as well. The moving mass came in quite a bit lower than the factory spec but this is offset by a softer suspension compliance and lower Bl. I suspect that 520 grams or so is very close to the actual weight.

Stereo Integrity 18" HST-18 Ver2 (2015) Systems