Pulsar Audio introduce IPA 25 plug-in

Published 23/9/25

Emulates and expands on classic VCA design

Pulsar Audio’s latest release aims to capture the sound of one of the most popular dynamics processors around, but rather than presenting a like-for-like emulation, the company have instead chosen to include a selection of handy extra features. IPA 25 is said to deliver the compression character that you’d expect from its inspiration (API’s much-loved 2500), but with some added functions that include selectable circuit topologies, intelligent clipping/limiting, visual side-chain control and a modular signal flow.

Operation Modes

The new plug-in is equipped with a choice of operation modes. Here’s what Pulsar Audio have to say about them:

Clean VCA: Transparent envelope control with no added harmonic content.
Original Hardware VCA: Punchy, precise and faithful to the legendary circuit, with subtle harmonic rounding when pushed.
V-Mu: Tube-inspired saturation with softer transients and a warm low-mid bloom.
N-Diode: Diode bridge grit with asymmetrical clipping and enhanced midrange presence.

The selection of modes allow IPA 25 to deliver to a wide range of different sound characters, and when switching between the modes, the plug-in’s detector and settings will remain the same — the difference in character is down to the sound of the gain-reduction stage. This makes it possible to quickly audition the different sound characters offered by each mode without needing to tweak any settings or adjust the plug-in’s I/O levels.

The plug-in also benefits from a carefully thought-out side-chain section that aims to provide detailed control over how the processor applies its gain reduction. The following options are provided:

Punch Selector: Original Norm, Mid and Loud modes, shifting detector focus across the spectrum
Visual Side-chain EQ: Four flexible bands that make it possible to draw exactly which frequencies drive gain reduction.
Stereo Linking: Control how and when channels share reduction — sustained levels, fast transients or anything in between.
External Side-chain: Trigger from any source for ducking, pumping, or creative movement.

New Additions

As is often the case with software recreations, IPA 25 has been treated to some nice-to-have extras that go beyond the capabilities of the hardware that inspired it. Here’s what’s on offer:

Integrated Intelligent Clipper & Limiter section with flexible routing.
Visual side-chain EQ display with free-draw curves.
Mid/Side & Stereo Link operation (feed-forward or feedback).
Look-ahead & look-behind functions for precision envelope timing.
Zero-Latency Mode for real-time tracking.
External side-chain support.
Low CPU usage with optional oversampling.

Pulsar Audio say that the new Clipper/Limiter section offers a great way to add density to a mix. The Limiter has been designed in a way that allows sustained low-frequency sounds to pass through untouched while transient-rich signals are treated to some subtle saturation, avoiding the ‘flat’ and ‘choked’ feel associated with conventional limiting processes. The Clipper can then be used to tame level jumps in an effort to prevent them triggering an excessive amount of compression. The module can be placed in three positions: pre-compressor, pre-mix and post-mix.

Compatibility

IPA 25 is supported on PCs running Windows 7 and higher, and Macs running macOS 10.11 or later. VST2, VST3, AU and AAX plug-in versions are available.