SMA™ – Symmetrical Magnet Assembly

The newly developed magnet assembly in the bass driver, which ADAM Audio has named the SMA™ (Symmetrical Magnet Assembly), extends the maximum possible excursion of the electromagnetic voice coil by a factor of three compared to previous designs. The greatly extended travel ensures that the membrane operates in linear fashion over a relatively large distance, displaces a greater volume of air, and is capable of higher maximum output. The design allows the driver to accurately reproduce low-frequency signals without distortion, even when called upon to produce extremely large excursions. An ingenious built-in ventilation system also prevents warming of the large, custom-designed voice coils, and thus reduces the effects of power compression below the threshold of audibility. As voice coils warm, their ohmic resistance changes, damping and dynamic range are reduced, operational parameters change, and low frequencies are no longer reproduced cleanly. These unwanted effects are avoided in ADAM Audio’s new design.

The carefully engineered construction makes use of materials designed to encourage heat dissipation, and also keeps unwanted air turbulence and compression out of the magnet assembly, minimizing distortion.

The SMA™ also features several other innovations developed by ADAM Audio especially for the S Series:An elongated pole piece is employed in the low-frequency driver, extending beyond the magnet assembly to widen the reach of the resulting magnetic field and also to render it symmetrical. This keeps the driver’s performance linear, and reduces distortion in the output to a minimum. The magnet assembly operates over a larger travel than other comparable low-frequency drivers, allowing the voice coil much greater scope for downward motion and preventing it from being damaged at high output levels. The pole piece is also vented to encourage ventilation and maintain constant pressure in the magnet assembly. To reduce turbulence and air noise, the venting is aerodynamically rounded.

The S2V, S3H and S3V’s parabolic pole pieces prevent unwanted modulation of the driver’s magnetic field, drastically reducing non-linear second-order distortion, while demodulation rings help the magnetic field remain symmetrical and also minimize non-linear third-order distortion.

The largest S Series models, the S5H and S5V, have an additional refinement: another magnet of opposing polarity is situated on top of the elongated pole piece to further streamline the magnetic field lines and render them symmetrical. This ensures that the movement of the voice coil remains linear and keeps distortion to a minimum, even at high listening levels.