MKS Mixing has released DelayU-42, a free vintage-inspired delay plugin for macOS and Windows.
DelayU-42 recreates the sound of classic 80s rack delays, focusing on grit, saturation, limiter behavior, and dark echoes.
Although MKS Mixing does not name the original unit directly, I’m guessing it’s the PCM42, but it could also be the Korg SDD-3000 or some similar piece of hardware.
The interface is simple. You get Power, Input, Output, Mix, Feedback, and a delay time section that can run in raw millisecond mode or tempo-synced mode.
Delay time goes from 0 ms up to 4800 ms in DLY mode, while CLK mode locks the delay to musical subdivisions based on the host tempo.
The Input control is very important because it drives the signal into the delay circuit. Push it harder, and you get more saturation, with the modeled opto-limiter reacting sooner. You can try pushing the Input and lowering Output to get more saturated delay throws.
The Mix control also does more than simply balance the wet and dry signals. It affects how much of the limiter and saturation character is present in the output, so the analog-style color can remain active even at lower mix settings.
So it totally makes sense to use DelayU-42 as a saturation box. Set Feedback to 0, delay time to 0 ms, push the Input, and blend with Mix to bring in the limiting and saturation character without using it as a traditional echo.
The plugin also models cascaded filtering, where each repeat progressively darkens. That is useful on vocals and lead parts because the delay tail naturally sinks behind the dry signal instead of fighting for the same top-end space.
Another nice addition is the dual opto-limiter in the feedback path. It lets you push feedback into more aggressive territory, including self-oscillation, while smoothing transients instead of crashing straight into harsh digital clipping.
The latest update includes denormal protection to prevent CPU spikes, safer sample-rate allocation, and DSP stability fixes.
DelayU-42 is available as a VST3 plugin for macOS and Windows. To install it manually, copy the .vst3 folder to the standard VST3 plugin directory on your system and rescan your plugins in the DAW.
UPDATE: The developer has just released the AU and CLAP versions of DelayU-42. This means it now officially supports macOS and Linux in addition to Windows.
Download: MKS Mixing DelayU-42 (FREE)
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Last Updated on July 6, 2026 by Tomislav Zlatic.
