Ascendo The24 SUB PRO

The24 is where Ascendo's infrasonic range starts, and it is the model that established the approach the larger ones scaled up. The driver is a 24-inch woofer on a dual 5-inch voice coil with 45 mm of travel in each direction — 90 mm of linear stroke, which Ascendo claims as a record for cinema subwoofers. Each stroke moves close to 20 litres of air.

The argument for one large driver over several small ones is group delay. Because the resonance frequency is very low and the enclosure sealed, The24 settles faster at a given frequency than an 18, 15 or 12-inch cabinet does — and it produces more acoustic output per cubic inch of enclosure than a stack of smaller subwoofers occupying the same volume. Bass that arrives late and leaves late sounds slow no matter how much of it there is.

Measured without external DSP it reaches 28 Hz at −3 dB and 20 Hz at −15 dB, so in practice it is specified with DSP and, in the largest rooms, alongside The32 or one of the two on-site models above it.

Worth knowing for two-channel: a great deal of the recorded room information in a well-made acoustic recording sits below 30 Hz. Rooms that reproduce it tend to sound more resolved further up the range, which is not what most people expect a subwoofer to do.