Specifications

Algorithm overview

Thank you for your purchase of the PSP Xenon!

PSP Xenon is a full band, dual-stage limiter featuring an integrated Leveller, advanced K-Sys-

tem metering and psychoacoustically optimized wordlength reduction. PSP Xenon offers 64-bit

precision processing throughout its entire signal path, and can operate at sample rates up to

192kHz.

Once you experience for yourself the pristine, transparent response and intuitive design of this

plug-in, we believe it will become your “go to” limiter for mastering and other critical audio ap-

plications.

PSP Xenon’s Approach to Limiting

PSP Xenon’s limiter section consists of two processing stages. The first section applies the ini-

tial gain reduction while allowing the transients to exceed the ceiling level (fixed at 0dBFS).

The longer the Attack time, the more transients will exceed the ceiling level. This stage uses

multiple Infinite Impulse Response (IIR) higher-order filters for intelligent adaptive envelope ex-

traction to ensure low aliasing and intermodulation distortion. This section uses only a small

amount of lookahead.

The transients which pass through the first stage are then subject to processing by the second

stage of PSP Xenon’s limiter section. This stage provides fail-safe (brickwall) limiting by using

lookahead processing in conjunction with sophisticated Finite Impulse Resonse (FIR) based

envelope detectors. By using FIR-based filters for the second stage, this guarantees that

every single transient will be detected and caught. This two-stage operation results in much

greater control over how the transients are affected than in traditional single-stage limiters.

Finally, the limiter envelope detector can be oversampled to automatically prevent intersample

peaks introduced by the reconstruction filter at the digital-to-analog converter. This way an en-

gineer will not need to lower the output level of the entire signal anymore—PSP Xenon’s envel-

ope detector does it automatically whenever required. The result - greater loudness at reduced

distortion.

The Integrated Leveller

PSP Xenon also includes an integrated Leveller which compensates for volume changes in the

program that occur over longer periods of time. To understand how the Leveller functions, you

need to be aware that the average level and loudness of a given audio signal cannot be in-

creased infinitely for a given release time. There is a threshold, dependent on the specific au-

dio material you are limiting, above which increasing the limiter input gain will not result in

greater perceived loudness. Instead, the limiter will start to pump heavily whenever it recovers

from moments of deep gain reduction. In this situation, there is nothing gained by increasing

the input level above that threshold level.

PSP Xenon Operation Manual