Manley Stereo Variable Mu Limiter/Compressor with T-Bar Upgrade Option

Newer Variable Mu units use 5670 tubes instead of the 6386. By now the availability of the original USA GE 6386 is poor, and what Manley does have are not usable due to noise, microphonics, bad side-to-side match, etc.

So does the 5670 sound different? Well, up to about 6 db 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 mitigate these issues, the Variable Mu is available with 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 curve.

The renowned Manley Stereo Variable Mu Limiter/Compressor is a favorite of producers and recording engineers - and one listen to what this device does for your sound will make you a believer, too! Anyone who has heard the classic Fairchild 670 Series limiters in action has an idea of this Variable Mu's capabilities - but the sound is even sweeter with the Variable Mu. Its adjustable attack and release settings are optimized for mixing and mastering, but are flexible for most tracking situations. Sonically versatile and dependable for daily use, the Variable Mu is Manley's best-selling device.

Although the Variable Mu is not a clone of one, the Fairchild 670 series used a similar limiting principle and those who are familiar with that piece of gear know this method to be very special. In fact, with "mu" meaning gain or amplification factor, the Variable Mu offers true variable gain, unlike most devices. How it works is that the unique 5670 dual trioide is at the center of the peak-reducing and compression action - and it's constantly being re-biased by the vacuum tube rectified side-chain control voltages. This causes the tube to smoothly change its gain.

The Varible Mu's Compress mode is 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 used by turning up the Input and turning down the Outputs while using very little or no compression.

Perfect for dual-mono or stereo applications You might notice that the Vari-Mu has a ganged input control, but it's certainly not mono-unfriendly. There are separate threshold 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 what th Variable Mu does better than anything else: final mix, 2-track, or mastering limiting and compression. Like one reviewer put it: "It's like pouring a bowl of sweet cream over the mix."

FEATURES:

• Manley input & output transformers with pure nickel laminations in mu-metal case with flat frequency response
• 20 Hz - 25 kHz frequency response
• Balanced inputs & outputs
• 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. (Not a 12-step recovery)
• Variable attack: 25msec - 70msec
• Continuously variable threshold
• Switch for limit or compress modes
• Front panel mounted meter adjust
• Limit (4:1 to 20:1) or compress (1.5:1)
• Large illuminated sifam meters
• Stereo link switch
• Maximum gain: 35 dB
• <0.1% THD @ 1 kHz Noise floor: -85 dB typical
• Max. output +30 dBm (26 V RMS) 26 dB Headroom
• Power consumption (120/240 VAC): 80 watts
• Dimensions: 19" x 3.5" x 10" (occupies 2u)
• Shipping weight: 23 lb