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Thermionic Culture
Phoenix Mastering Plus Stereo Valve Compressor

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Item: N13-3041

Availability: In stock

Phoenix Mastering Plus Stereo Valve Compressor
Phoenix Mastering Plus Stereo Valve Compressor Phoenix Mastering Plus Stereo Valve Compressor Phoenix Mastering Plus Stereo Valve Compressor


The Thermionic Culture Phoenix Master Stereo Compressor is the latest development in the evolution of the classic Phoenix compressor, first introduced in 1998. After requests from mastering engineers the Master Phoenix was introduced in October 2006. This was more recall-able with indented pots and slightly different power supply and metering circuit, in which trimming the meter alters the current through the compression valve so compensating for valve ageing.

The compression curve of the mastering Phoenix is slightly gentler than that of the standard one, but it does have a more "positive" effect. This earlier version has 6dB lower gain compared to the standard Phoenix. The Master Phoenix is in use in many studios and mastering suites around the world, and we do know that one of its users, Ray Staff of AIR London Studios won the MPG award for Best Mastering Engineer in 2009.

The new Mastering Plus is a much upgraded version employing precision Elma switches for the Gain and Threshold and Alpha switches for Attack and Release. Omeg indented pots are used for the Output Level for fine control. Side Chain Bass Cut switches, which have become an essential mastering tool have been retained. In stereo mastering, with the link switch in, there are effectively 5 frequency options as the compressor side chain will work at the average of the switch positions.

A Standby switch is introduced to prolong valve and component life and this has had an unexpected effect. Some users have found that analogue tape type distortion is created when the unit is operated with Standby on.This was unintentional but some people may find it interesting.

Mullard and Siemens NOS valves are used exclusively for lower noise and long life stability. The Gain is now identical to that of the standard Phoenix so that extreme compression effects are possible. Easy adjustment of Meter Zeros, especially important in stereo mastering, is now enabled by front panel access to the trim controls, situated between the 2 meters.


  • All valve signal path and side chain, point to point hand wired in England
  • Subtle control with 'soft knee' compression more compression effects when pushed hard
  • Stereo link for mix buss compression
  • Side chain filters to enable compression of all frequencies except bass
  • Flat frequency response over full audio range and beyond
  • Very low phase shift and harmonic distortion (unless pushed hard)
  • Push-pull design gives a natural warm sound with high output level
  • Output trim controls for fine adjustment or lower level operation
  • Balanced ins and outs with custom made Sowter transformers
  • Bypass switch on each channel removes all electronics
  • Elma switches for gain and threshold controls
  • Alpha switches for attack and release controls
  • All Mullard and Siemens NOS valves
  • Easy recall- ability
  • Zero adjustment on front
  • Precise calibration
  • More gain than earlier Master Phoenix
  • Standby switch to prolong valve life
  • Distortion effects can be created with standby on

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  • Max. o/p level (MOL): +19dB into 600Ω, +24dB into 10kΩ
  • Max gain: 30dB
  • THD (at no compression): better than 0.06 % @ 100Hz & 1kHz
  • Noise, IEC weighted: better than 100dB below MOL
  • Input impedance: 15kΩ
  • Frequency response: <1dB variation over range of 12Hz to 56kHz
  • Attack time: 0.004s to 0.12s
  • Release time: 0.04s to 2.4s
  • Output impedance: 600Ω

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