1800W AES, 125 mm coil, £275
An 18" sub bass driver with a vented ferrite motor and a 125 mm voice coil on a glass fibre former, rated 1800W AES and 3600W peak into 8Ω. That is 15.3p per rated watt.
Sensitivity is 93.5 dB at 1W/1m. Sd is 1,244 cm² and Xmax 12 mm, for a displacement (Sd × Xmax) of 1,493 cm³. The vented motor moves air through the pole piece to carry heat away from the coil, which limits power compression on long sets.
Designing a cabinet around it
With Fs 42.9 Hz, Qts 0.644 and Vas 120.9 litres, the WM1850/8 suits reflex and mixed systems, and it is also used in scoops. Put the full Thiele/Small set into the box designer in our speaker tools, or read Thiele/Small parameters explained. Swapping it into an existing cab? Check the 392 mm cut-out and 202 mm mounting depth with will it fit? first.
Powering it
An 8Ω driver is an easy load: a pair in parallel presents 4Ω to one amplifier channel. Set your limiter from the AES rating, as shown in limiter settings for subs, and see how many amp channels a stack needs.
Book a listening room visit to hear it loaded in a cabinet before you buy.