Kjaerhus MPL-1 Pro review

  • $118

Everyone needs a good mastering limiter in their arsenal. Does this one fit the bill?

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Our Verdict

Another great plug-in from Kjaerhus. There are loads of limiters out there, but the MPL-1 more than holds its own.


  • Almost transparent when used at oderate settings. Excellent metering. Well designed interface. Low CPU consumption. Good value for money.


  • Output dithering lacks noise-shaping options. Lacks a bit of character for some applications.
Buying options

It takes balls to enter the limiter plug-in market at present. After all, countless developers are competing for the honour of being the ones to put that ‘final polish’ on your mix.

Luckily for Kjaerhus, they’re a company who’ve earned a reputation for producing quality plug-ins that go the extra mile in terms of both sound and flexibility. The MPL-1 Pro Mastering Limiter is no exception, as it delivers an extremely musical sound and some unique features.

Installing the plug-in is a breeze, and the first time you load the MPL-1 it becomes apparent that the interface is very clear and doesn’t hog your screen. The familiar Threshold and Release controls are located across the middle of the GUI, and sit alongside the Gain control (this is set to Auto by default). Smaller knobs are used to tune the limiter’s response – in particular, the maximum release time when the Program Dependent Release is activated – and to put you in control of the Stereo Link Time.

The top of the window is occupied by an excellent metering section that features an RMS level meter. This more accurately represents the way we perceive average loudness than peak metering, and we’re amazed that this type of metering isn’t included as standard on all mastering limiters.


Kjaerhus are keen to market the MPL-1 Pro as a transparent final limiter, and in that respect, they really have nailed it. Between 6-8dB of limiting is effectively completely transparent on a well balanced mix; the plug-in simply adds punch and overall loudness with no shift in frequency balance. The limiter’s smoothness is due in part to the peak detector input being oversampled to reduce any peak detection errors, while the Program Dependent Release implementation is one of the best and most intuitively tweakable auto release settings we’ve heard.

You can get the limiter pumping at high gain reductions for extreme effects, but the MPL-1 isn’t designed as an ‘effects’ limiter, so this isn’t its strongest point. The final output can be dithered to 8-, 16- or 24-bit, and though the dithering options are limited, they do get the job done.

The MPL-1 Pro has a reassuringly open sound to it, and while the jury is still out on whether the loudness arms race is a good or bad thing for music, the fact remains that if you want to transparently boost your final master, you really can’t go wrong with this.

Tech Specs

DescriptionMastering Limiter Plug-in
OS RequirementsApple Mac Os X or later Microsoft Windows 2000 Microsoft Windows XP
Plug-in FX TypeMastering
Processor Type RequiredPowerPC