Klanghelm’s MJUC is a variable-mu compressor, which is the oldest (and arguably least common) type of compressor available. Also known as a tube compressor, variable-mu units use tubes to control the gain stage, resulting in a sound that is rich and warm. Traditionally, compression ratio was dependent on the amount of signal pushing into the circuit and, as this is older technology, attack is usually slow with a soft knee. This allows transients to pass through uncompressed, making them particularly suited to bass, vocals, and the mix buss.
MJUC features three variable-mu models of varying complexity, ranging from the rather simple and highly coloured Mk1, to the Mk2, which adds FET-style controls for attack and release and an interstage transformer to reduce noise and distortion.
MJUC sounds amazing and punches well above its price point of €24. This is an absolute monster of a compressor for a kitten of a price. If you’re still not convinced, check out the free “junior” version, MJUC Jr.