The MANLEY VARIABLE MU® LIMITER COMPRESSOR has been our best-selling product for many years. It's one of the few compressors that has become a true standard in mastering studios and has contributed to most of the hit records of the last decade and probably the next. "Mu" stands for tube gain and Variable Mu® is our trademark for this limiting compressor. It works by using "remote cutting" or re-polarizing a vacuum tube to achieve compression. The precious vintage Fairchild 670 also uses this technique and is one of the few all-valve compressors we know of. Even the side chain has shiny rectifier jars. How it works? The unique 5670 dual triode is at the heart of the peak reduction and compression action, being constantly re-biased by the vacuum tube's rectified side-chain control voltages, which cause this tube to smoothly change its gain. Just like that.

COMPRESS mode has a smooth 1.5 to 1 ratio, while the sharper knee LIMIT mode starts at 4 to 1 and moves to a more dramatic 20 to 1 ratio when limiting above 12dB. Interestingly, the knee actually softens as more restraints are used. Distortion can be used creatively by increasing the input and decreasing the output using very little or no compression. See the gain reduction curves here!

You may notice that the Variable Mu® Limiter Compressor has a ganged input control, but don't jump to the conclusion that it is mono-hostile. Track! There are separate threshold and output controls for making compensations, and you can always adjust your individual source levels elsewhere, right? The advantage of stereo input control becomes dramatically clear when you switch to LINK mode, and that's what our Variable Mu® Limiter Compressor does better than anything else: final mixing, 2-track or mastering, limiting and compression. As one reviewer said, “It’s like pouring a bowl of sweet cream over the mixture.” Hmmmm. Delicious. Give your music a big hug.

From Adele to David Bowie, from Amy Winehouse to Beck, Tom Elmhirst's Variable Mu® has been your “right hand” on your mixing bus for two decades. We spent some time in his room at Electric Lady Studios in New York, learned how he uses it, and heard it in action in a mix – watch this video to hear it for yourself.