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Manley Nu Mu Stereo Limiter Compressor

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Manley Nu Mu Stereo Limiter Compressor

Postby Glenn Bucci » Fri Feb 24, 2017 2:49 am

Manley Laboratories Inc. (Manley Labs) is an audio company in southern California that takes pride in manufacturing high quality pro audio and hifi audiophile gear. EveAnna Manley has been at the helm at the company since the mid-1990’s and is passionate about tubes and moving the company forward in today’s audio industry. Manley Labs manufactures several now-legendary pieces of gear including their Variable Mu® Stereo Limiter Compressor which has become ubiquitous staple in recording and mastering studios around the world. This unit is renowned for its wonderful character that can add a pleasant color to your 2 bus mixes, vocals or instruments. The Variable Mu is known as the unit that adds a magical glue to your mix.

With today’s pop and electronic music having a lot of top end, sparkle, and solid bass, many engineers want to maintain this in their mix. Also remembering how far digital converters have come since the olden days, there is less need to color or mask or change sonic character. Therefore, Manley Labs decided to come out with a new dynamics processor that had a cleaner character compared to their Variable Mu® while still providing the smooth tube character that is so sonically seductive.

Manley’s new compressor is called the Nu Mu Stereo Limiter Compressor. The challenge EveAnna gave to her team was to design a high-quality tube compressor that costs a lot less than the older Variable Mu unit without taking short cuts with the quality of components or moving production overseas. Manley’s recent offerings such as the Manley CORE® Reference Channel Strip and Manley FORCE® 4-channel microphone preamplifier achieved these goals primarily by increasing the efficiency of the build method minimizing tedious labor-hours required to assemble the unit, in Southern California, please note! The design has the same front end transformer and first tubes as the Variable Mu’s special TBAR Mod using two 6BA6 pentodes strapped as triodes per channel. From there the signal goes into high voltage discrete transistors and FETs for the amplification and output stages. There are no op-amps in the signal path. So how else did they make this unit so affordable? The outputs are transformerless in the Nu Mu which saves a ton of money on the Bill of Materials while also yielding more transparency. The Nu Mu has half the number of vacuum tubes compared to the Variable Mu. The side-chain rectifying tubes of the Variable Mu were easily and cloned using solid-state diodes plus a resistor. Creatively, they were able to match the characteristics and speed of the vacuum tube diodes saving cost, hassle, and heat and drain on the power supply. So, the way the signal gets converted from AC signal into a DC control signal is done with the same reaction as the Variable Mu. Manley’s newest units all reside in a smaller chassis than the 1990’s designs. The main board holds all the I/O connectors minimizing hand wiring. The layout of this unit makes it build fast shaving off hours of expensive American labor.

The Nu Mu front panel includes solid feeling controls for Attack, Threshold, Recovery, Ratio (Compress vs. Limit), Bypass, and Link features. There is also an input level switch that goes from -3db to +3db. A new HIP switch allows compression at lower dynamic ranges, while leaving louder dynamics unaffected. There is a big beautiful stereo meter in the center of the unit that switches to show the output level or reduction amount of the signal. Unit is powered on by the front panel mounted power switch.

I ran the Manley Nu Mu on various types of mixes from rock, jazz, and contemporary Christian music. I found the HIP button to be extremely useful. It makes the compressor not react so quickly to the low end content in the music. I generally reduced the signal by one to two dBs with a slow attack and fast recovery which is a common setting for the Variable Mu as well. In tracking situations, the Nu Mu also does a great job on vocals and acoustic guitar. I found it has a similar overall character to the Variable Mu but the level of color was less and provided a clearer sound. In using colors to explain the tone difference, the Variable Mu would be brown color, while the Nu Mu is more of a tan color. It’s not as clean as the Pendulum ES-8 as the Nu Mu adds a gentle character to the sound. The Nu Mu sounded great with every style of music that I put it through and it has the ability to remove harshness from cymbals while getting the mix to gel nicely. If you hit the mix harder, you will obviously get more color from the unit as well. In comparing the Nu Mu to some of the newer plug in compressors, I will admit many of these plug ins do sound good, however I would say that most of them sound like they are on top of your signal while the Nu Mu sounds like it is part of your signal.

This unit is a high quality and versatile limiter compressor. I think Manley hit this one out of the park with its much lower price over their Variable Mu, its sound and features.
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Glenn Bucci
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Re: Manley Nu Mu Stereo Limiter Compressor

Postby Martin Walker » Fri Feb 24, 2017 9:53 pm

Thanks Glenn - a great write-up that is truly informative!

I particularly like your description of brown and tan tone colours, which made perfect sense to me 8-)

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Re: Manley Nu Mu Stereo Limiter Compressor

Postby Warm Mastering » Thu Mar 02, 2017 1:48 pm

Great and detailed review, thank you!
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