Mercury 666


Mercury Recording Equipment Mercury 666 MKI

The Mercury 666 is a new version of a mysterious classic… the Fairchild 666 which is not as well known as the Fairchild 660 (like our Mercury 66) or the Fairchild 670. We always try to be faithful to the original we are paying homage to, but in this case, so many changes needed to be made to make it more useful for modern recording we felt it was a great opportunity to make it the ultimate benchmark in modern tube compressors/limiters. We made the Mercury 666 quieter, more flexible, and added an expanded feature set that is second to none, let alone better than the original. Our goal was not to make it ‘as good’, but beyond better, and we feel we succeeded in doing that.

The Mercury 666 is a hybrid solid-state and valve (tube) Studio Limiting Amplifier (compressor). The new, ’Mercury SSGRE’ (solid-state gain reduction element) is a gain attenuator that does not provide any gain to the signal. All of the gain makeup after the ‘SSGRE’ in the Mercury 666 is provided by a separate single-ended, tube, gain make-up amplifier. Using a 12BH7 valve (tube) and a custom U.S. made (Cinemag) output transformer.

The Fairchild 666 had a feature set that did not allow it to be flexible enough for modern recording with compression control, compression release, gain control, input level, and “auto-ten” functions for threshold and for release (note: auto-ten = Auto attenuation). Most features did not even have a knob you had to use a screwdriver for the control. So we designed the Mercury 666 to be more of a modern, hybrid 660 with any and all features you might need at your fingertips.

Key Features:

  • Link Switch with LED for Stereo operation
  • Zero Control for easy meter calibration
  • Meter Select Switch for gain reduction or output level monitoring
  • Threshold Control with 11 position pot for easy recallability
  • Attack Release Switch (Time Constant) with 11 attack/release settings

Attack Release Settings:

  • Position 01 – Fast Attack w/ Fast Release, Attack [ 0.4 ] Release [ 0.1 ]
  • Position 02 – Medium Attack w/ Medium Release, Attack [ 0.8 ] Release [ 0.6 ]
  • Position 03 – Medium Attack w/ Medium Release, Attack [ 0.8 ] Release [ .90 ]
  • Position 04 – Slow Attack w/ Slow Release, Attack [ 1.6 ] Release [ 1.75 ]
  • Position 05 – Medium Attack w/ Med. Release, Attack [ 0.8 ] Rel. 1 [ .90 ] Rel. 2 [ .75 ]
  • Position 06 – Fast Attack w/ Fast Rel, Attack [ 0.4 ] Rel 1 [ .45 ] Rel 2 [ .75 ] Rel 3 [ 2.0 ]
  • Position 07 – Fast Attack w/ Medium Release, Attack [ 0.4 ] Release [ 0.45 ]
  • Position 08 – Fast Attack with Slow Release, Attack [ 0.4 ] Release [ 2.0 ]
  • Position 09 – (LA3A) Med. Attack w/ Med. Double Slope Rel, Attack [1.6], Rel 1 [.06], Rel 2 [3.13]
  • Position 10 – (GATES Sta Level) single slope mode, Attack [ .87 ] Release [ 7.26 ]
  • Position 11 – (GATES Sta Level) double slope mode, Attack [ .27 ] Rel. 1 [ 2.30 ] Rel. 2 [ 10.7 ]

The Output Gain Control allows you control of the amount of ‘make up gain’ after the signal has been “compressed” by using the Threshold Control.

The DC Adjust allows you to have even more control and flexibility. It works similarly to DC Threshold on a 660 or DC Adjust on our Mercury 66. This controls the voltage that increases or decreases the starting point when/where the “compression” starts at the ‘Mercury SSGRE’ (solid-state gain reduction element). Allowing more or less or a quicker or slower reaction to the input signal, similar to a Knee Control, allowing a variable swing between Less/Soft Knee/Less Voltage and More/Hard Knee/More Voltage. This control has an 11 position pot for easy recallability!

On the bottom row, to the right of the meter, is the Side Chain Filter Switch this is a three-position rotary switch. With an off position and 90 and 150 Hz filter settings for the side chain. This allows you to filter out low-end frequencies below 90Hz or 150Hz before going to the limiting amplifier but not affecting or “EQing” the signal.

The Insert On/Off Switch allows you to leave the insert connections (on rear of M666 chassis) connected, to your patch bay for example, and control if the insert is being used in the sidechain or not. When the Insert On/Off Switch is engaged (in up position) and the associated LED is illuminated, the connection from the side chain insert return is being sent to the side chain. When the Insert On/Off Switch is not engaged (in down position & the LED is off) the side chain no longer receives a signal from the Balanced Insert connections therefore bypassing the inserted signal.

The EQ. This is a two-band, *Baxandall EQ with a Low (Bass) and High (Treble). The EQ has Low (Bass) Control is +/- 10dB @ 20Hz and +/- 5dB @ 350Hz simultaneously. The Treble (High) Control is +/- 6dB @ 20K and +/- 3dB @ 2K5 simultaneously. Both High and Low Controls have 11 position pot for easy recallability. The EQ section is a great feature on the Mercury 666 Limiting Amplifier. It allows you to have so much control over the tone of the limiter and literally hands you the flexibility to get the sound that you’re looking for instantaneously.

* The Baxandall equalizer is a shelving EQ with an extremely wide Q curve and a gentle slope. The broad curve can adjust a larger portion of the frequency spectrum, but the gentle slope gives a more natural sound and very minimal phase distortion.

The Bypass On/Off allows you to listen to exactly what is coming into the device without going through any circuitry of the Mercury 666. If you engage the switch in the up position the LED will illuminate and you would now be listening to your source material directly. In the down position of the Bypass On/Off, this “hard bypass” is Off. But you also have more flexibility with the Mix Control (wet/dry). This allows you to mix between the “Wet” (100%) compressed output signal of the Mercury 666 or the dry, uncompressed (0%) source with 11 position pot for easy recallability. Note: signal is going through the circuitry of the Mercury 666 unlike the (Hard) Bypass. With the combination of these two features, the Bypass Control On/Off Switch and the Mix Control, or wet/dry, it allows you to hear the original source as well as an extensive range of blended source and the compressed signal, or “parallel compression.“

On the back of the Mercury 666’s gray hammer-tone chassis, there is an AC socket on the left side to take 115V (.400mA) or 230V AC (.200mA) and a Fuse Holder. On the right side, there is an input plate with gold pin XLRs for (Line) Input and Output. Under the Line Input and Output, are the Insert Send and Return connections using a Combination Jack, ie Female XLR and TRS 1/4” jack, for the Insert Return and another gold pin XLR for Insert Send. Below that is the Stereo Link Connector, which is a 1/4“ (TS) jack to connect from one Mercury 666 to a second M666. Activating the front panel Link switch (on both units) enables the Mercury 666 Limiting Amplifiers to be used as a stereo pair… making a stellar, flexible, & very musical two-bus compressor/limiter.

  • Threshold: inf to -20 dB
  • Output: -inf to 30 dB
  • Transformers: 600 ohm Input and Output
  • Gain: 7 dB (no limiting)
  • Frequency Response: 40 Hz – 15 kHz +/- 1 dB
  • Noise: = -74 dB below OdBm
  • THD: = < 1%
  • Compression Ratio: 1:1 to 1:20
  • Attack Time: [1] 0.2 ms, [2] 0.2 ms, [3] 0.4 ms, [4] 0.8 ms, [5] 0.4 ms, [6] 0.2 ms
  • Release Time: [1] 0.3 ms, [2] 0.8 ms, [3] 2 sec, [4] 5 sec, [5] auto 1, [6] auto 2
  • Tubes: (1) 12BH7
  • Rack Size: 3U
  • Weight: 38 lbs.
  • Shipping Size: 25″ x 19″ x 10″