Home of the XQP Optical De-esser

The XQP 531B Optical De-esser is the latest in the line of XQP optical de-essers that began back around 1996 with the Dane #31.

In an effort to produce a sibilance controller that sounds natural, the Dane #31 was developed in 1996 from a prototype designed as part of a console for recording audiobooks. The console was never built...at least not until 2022. Only around 30 of those original de-essers were built, but the design included several unusual features that gave the unit a distinctive sound - one which many claim is the best ever achieved - and those features survive to this day in the XQP 531B.

In 2009 XQP was formed to produce the optical de-esser in API's 500-series format. The 531 was an almost exact copy of the Dane #31 (although without the power supply or I/O connectors). One capacitor was added in the sidechain, and the use of dual parallel optocouplers was introduced.

The 531A was introduced in 2015 with the addition of a fourth frequency choice. A different method of switching frequencies was introduced as well as an additional pole to the filters for a slightly steeper filter response.

In 2022, to celebrate 25 years of the basic design, the 2531 was introduced in a limited number (35), and it featured a rotary switch in place of the Reduction pot along with a feed switch which added feedback and a blend position to the traditional feed forward. The 2531 introduced the stainless steel metalwork along with several different components, giving the unit a very different look and feel. However, the basic circuit design remained intact.

The 531B followed the 2531 with slightly different toggle switches and redesigned I/O amplifiers.