The Revelator woofers and subwoofers features very rigid cones in paper or aluminium that operates as a piston over a wide frequency range, in combination with Scan-Speaks low-loss linear suspension and the patented Symmetrical Drive (SD-1) it results in very low distortion and a smooth and well behaved frequency response as well as perfect transient reproduction.
Datasheet: Datasheet 22W/4851T00

Size (inches): 8
Fs (Hz): 21
Re (ohms): 3.7
Sensitivity (dB): 89
Qt: 0.22
VAS (ltr.): 126
Xmax ± (mm): 9

DIY kits for this driver:
Ellam Flex 3W made by Troels Gravesen