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Manley Stereo Variable Mu® Mastering Version (T-Bar Mod)  From Manley

The Variable Mu Limiter Compressor is the GLUE that holds the mix together while crystallizing it into a professional, final product. All-tube, all transformer, an all-American legend. High Pass Side Chain mod now comes standard.

Manley Laboratories Inc

$7,099.00

"Experience the Difference"

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Manufacturer's Description from Manley

The Mastering Version of the Variable Mu® Limiter Compressor incorporating detented and logable steps built with 1% metal film resistors on sealed gold-contact Grayhill switches is available. NO, they will not mod a "normal" unit to the Mastering Version. The Mastering Version of the Variable Mu Limiter Compressor uses expensive Greyhill rotary switches with gold contacts where conductive plastic pots were used. The steps are determined with a large number of 1% precision metal film 1/2 watt resistors. The best conductive plastic pots only have 10% or 20% tolerance. The ten fold improvement in precision helps a great deal in left-right matching. There is a subtle audible improvement with stepped switches as well. Audiophile HI-FI often uses that technique to wring the last drop of performance out of a preamplifier. And I bet you wanted stepped switches mostly for resets.

 

The INPUT LEVEL is a five position switch with a generic optimum setting of “0” in the 12:00 position. Each step in either direction is 2 dB. For reference, Unity Gain is "0".

The OUTPUT Attenuators are in half dB steps. Reference Unity is -11.5 or fully counter-clockwise. You might think of these as "gain makeup". They are marked technically, in that “0” or fully clockwise has zero attenuation in the circuit. The tube circuit actually has 15.5 dB of gain. The Input attenuator at "0" removes 4 dB and the Output attenuator removes the last 11.5 producing "unity". With a little compression the "gain make-up" available with the Output Attenuator is very handy.

The Threshold is in half dB steps calibrated to LIMIT mode. In Compress the steps are approximately 1/4 dB. There are 24 steps so LIMIT gets a 12 dB range and Compress has a 6 dB range of adjustment. In some cases it is common to use the Input Attenuator to find a good starting point. Some Mastering engineers find using the combination of Input, Output and Threshold to achieve a little different "drive". Another good reason for stepped gains.

 

THE T-BAR MODIFICATION

Backstory: The newer Variable Mu units use 5670 tubes instead of the 6386. By now the availability of the original USA GE 6386 is poor; we don't have any left at all, and what we do have are not usable due to noise, microphonics, bad side-to-side match, etc.

So does the 5670 sound different? Well, up to about 6db of limiting it's about the same. After that point, the 5670 version tends to sound more "squashed" than the original 6386 version. Some like it better, some don't - depends on what you're trying to do.

To solve all these problems, Paul came up with a really good solution: the T-Bar Mod. This uses a pair of 6BA6 pentodes wired as single triodes to replace each dual triode 5670 (or 6386). The 6BA6 T-Bar Mod is the preferred system to use in the Manley Variable Mu® for reasons of ability to perfectly match each phase-halve section and each stereo set, ability to select for lo-noise and lo-microphonic sets for a low cost, and because the action of the 6BA6's so closely resemble the smooth 6386 limiting curves.

Manley Laboratories Inc

About Manufacturer

The MANLEY brand has been around since the late 1980's. Manley's first commercially available products were upper echelon high-fidelity vacuum tube amplifiers and preamplifiers constructed at the old Vacuum Tube Logic of America factory.

In this history lesson, we'd like to direct special focus on our people at Manley Labs. The people whose years of dedication, service, and expertise bring you people, our customers, these products. It's all about the people...

On January 30, 1989, a 20 year old EveAnna on sabbatical from her studies at Columbia University met the crew and was hired on to the production team. Baltazar Hernandez, already with two years experience, taught her how to solder in those first few days. It was in 1989 that the first Manley professional products were developed, starting with the original 1u Reference 60dB Microphone Preamplifier and soon followed by our Manley Enhanced Pultec and Mid Frequency Equalizers. Baltazar and EveAnna, busy building gear, were soon joined by Saulo and Ramiro. Just next door, Elias was employed by a printed circuit board maker later brought into the Manley Labs fold when in 1993, Manley Laboratories, Inc. became a separate entity apart from VTL. The new Manley Labs factory at 13880 Magnolia Ave. in beautiful and bovine Chino, California was outfitted to house the Manley HiFi and Pro Studio manufacturing as well as the Langevin production lines, our newly acquired machine shop, and printed circuit board facilities.

Specifications

The Attack Time has been slightly extended in both directions compared to a regular Variable Mu and divided into 11 steps. 

The Recovery 5 position switch is exactly the same as a regular Variable Mu.

 

The switches specifically are like this:

Input: -4 to +4 in 2 dB steps

Output: -11 to 0 in 1/2 dB steps (24 detents) 

Threshold: -11 to +1 in 1/2 dB steps LIMIT(24 detents) and 24 x 1/4 dB steps in COMPRESS

Attack: 11 positions CW (fast) 15mS, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90mS (slow) CCW

Release: 5 positions CW (fast) 200mS, 400mS, 600mS, 4S, 8 Seconds (slow) CCW