RX9-HF from Primacoustic is a speaker decoupling device that helps improve monitor speaker performance. Although there are several manufacturers providing a similar kind of solution, the RX9-HF is different in that it also takes into account what is known as speaker recoil.
All isolation pads help speaker performance by eliminating the transmission of speaker-cabinet vibration to the surface they are resting on. This is because the additional sympathetic vibration of the support medium (stands, meter bridge, etc.) that is produced when using non-decoupled speakers, smears stereo imaging and can cause unwanted frequency boost or cut.
Where the RX9-HF differs is in preventing back to front speaker cabinet motion (recoil), the result of a speaker coil pushing energy forward. This is more prominent with larger speakers and when monitoring at high volumes and can actually be exacerbated by the use of plain foam pads, given the latter's inherent pliability. By containing this motion, the RX9-HF allows the speaker to deliver significantly greater detail at all frequencies, with tighter bottom end and improved depth of field.
The Recoil Stabilizer is constructed from a high-density urethane base onto-which is added a heavy laser-cut steel plate, covered by a non-slip neoprene top. The steel plate introduces significant mass to the structure and serves to stabilize the speaker. The RX9-HF is constructed to allow the speaker to sit flat on the pad and "fire" in a horizontal direction.