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Manley Variable Mu Stereo Limiter Compressor - Mastering Version

Dual-channel Tube Limiter/Compressor with Detented Rotary Switches and True Variable Gain
$6,599.00

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Manley Variable Mu Stereo Limiter Compressor - Mastering Version
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An Industry-standard Mastering Tool

The Manley Variable Mu Mastering Version is the perfect addition to any professional mastering facility. In fact, having been deployed on countless hit records since its introduction, it’s quickly become an industry-standard mastering tool. Unlike the standard version of this 2-channel, all-tube, transformer-coupled limiter/compressor, which uses smooth-moving pots, Manley specified precision rotary switches with detented steps for the Variable Mu Mastering Version to facilitate precise left/right channel matching and settings recall. Anyone who has heard the classic Fairchild 670 limiter in action has an inkling of the Variable Mu’s capabilities, but the sound is even sweeter with the Variable Mu. A modern all-American legend, the Variable Mu Mastering Version fortifies your mixes with glue and punch, crystallizing them into professional, radio-ready product that blasts right out of the speakers.

The Variable Mu Mastering Version’s adjustable threshold, attack, and release settings are ideal for tracking and mixing, as well as mastering; while its highpass sidechain gives you added flexibility. Although optimized for mastering, the Manley Variable Mu Mastering Version is a high-end, esoteric piece of kit that delivers miraculous results on individual tracks and stems. It’s also incredibly versatile and rock-solid reliable for daily use. Add one to your studio rack, and hear what you’ve been missing!

A modern all-American legend

Although the Variable Mu is not a clone of one, the Fairchild 670 series used a similar operational principle and engineers at Sweetwater who have used that legendary unit know this method to be very special. With “mu” meaning gain or amplification factor, the Variable Mu offers true variable gain, unlike most compressor/limiters. How it works is that the 5670 dual triode is at the core of the peak-reduction action as it is constantly re-biased by the tube-rectified sidechain control voltages. This causes the tube to smoothly change its gain, and is responsible for the Variable Mu’s unique and highly effective gain reduction behavior, which gives you maximum level control with minimal artifacts.

From light leveling to heavy limiting

The Variable Mu’s Compress mode is a soft-knee 1.5:1 ratio while the sharper knee Limit mode starts at 4:1 and moves to a more dramatic ratio of 20:1 when limiting over 12dB. Interestingly, the knee actually softens as more limiting is used. Distortion can be creatively employed by turning up the Input and dialing down the Outputs while using very little or no compression.

Perfect for dual-mono or stereo applications

You might notice that the Variable Mu has a ganged input control, but it’s certainly not mono-unfriendly. There are separate threshold, attack, release, and output controls to make compensations with, plus you can always adjust your individual source levels elsewhere. The advantage of the stereo input control becomes clear when you switch to Link mode. And that’s where the Variable Mu Mastering Version excels — on stereo buses and for mastering your final mixes. As one reviewer put it: It’s like pouring “sweet cream” over your mix!

Manley Variable Mu Compressor/Limiter Mastering Version Features:

  • Rotary switches with detented steps for precise channel matching and settings recall
  • Switch steps built with 1% metal film resistors on sealed gold-contact Grayhill switches
  • Manley input and output transformers with pure nickel laminations in mu-metal case
  • Flat frequency response from 20Hz–25kHz
  • Balanced Inputs and Outputs
  • Fully differential all-tube circuitry using one 5751, 7044, and 12AL5 per channel
  • Variable Gain vacuum tube (per channel): 5670
  • Independently regulated B+ and Heater supplies
  • Includes HP Sidechain modification as standard
  • Hard-wire Bypass switch
  • Silent conductive plastic input attenuator
  • Recovery 5 steps: 0.2s, 0.4s, 0.6s, 4sec, 8sec
  • Variable Attack: 25msec–70msec
  • Continuously variable Threshold
  • Switch for Limit or Compress modes
  • Front-panel mounted Meter calibration
  • Limit (4:1 to 20:1) or Compress (1.5:1)
  • Large Illuminated Sifam Meters
  • Stereo Link switch
  • Handcrafted in Chino, CA

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Tech Specs

  • Number of Channels: 2-channel, Stereo
  • Frequency Response: 20Hz-25KHz
  • Rack Spaces: 2U
  • Height: 3.5"
  • Width: 19"
  • Depth: 13.5"
  • Manufacturer Part Number: MMSSLCHP

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Customer Reviews

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Rated 5/5

100% Worth the Money

In this day and age with lots of plug-ins if you're going to buy hardware I believe in buying the best special sounding units. This has that something special. If you are not an audio perfectionist or have not been into the mixing in mastering for a while then don't buy this, BUT if yes then this will blow your mind. It glues like no other, brings a depth and color that is so musical and pleasing. I think the high pass and the mastering version are worth paying for. The T bar mod I don't feel like I really need. Unit sounds amazing as is. I highly recommend pairing this with an SSL or VAC type compressor to add punch to the mix and this one to add more glue and a bit of calmness. I work entirely in the box but have this piece, a bettermaker mastering compressor, and a Massive Passive EQ. I mix through them with all settings off, adjust later, and feel very happy with the outcome. I am just a home studio musician who loves music. If I did this for a living I would probably add a few more pieces. Highly recommend
Music background: Musician, Audio Perfectionist
Rated 5/5

Essential Piece

I have a unit with the M/S and TBAR factory mods, and it gets used on every mastering project that comes through my studio. The sound is amazing and smooth, and it glues everything together perfectly.

My unit developed an issue with the gain stepper, and I was able to get it serviced quickly and with no hassle at all and is now good as new.

(One warning: the unit does get HOT when in use. There are actual tubes in there, folks!)
Music background: Mastering Engineer, Musician
Rated 5/5

WOW... WOW... WOW !!!

Firstly, let me congratulate my sales consultant Brad Thomsen!

I was close to forever kissing Sweetwater goodbye until he was able to help me get the professional service that I require in the high stakes audio engineering and music production field.

I compose and produce music for television (200+ shows) and don't want any open boxes or lackluster delivery. I know what I want ... and there are few people that can offer words of wisdom.

In this world of software plugins and artificially modeled "crap a la crap"... true analog gear rules!

If you have the budget to afford a $5000+ mastering unit then this is certainly well worth the price of entry!

If you don't understand signal flow or TUBES then this unit is NOT for you. On the other hand, if you know your audio engineering and are dedicated to the craft.... then this unit is a no brainer and requires your immediate attention!

Long story short... if you have the money... and want the best audio mastering...then purchase this unit!!!!

- Michael
Music background: Composer of music for television.
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