Thermionic Culture Phoenix Mastering Plus Stereo Valve Compressor

The Thermionic Culture Phoenix Mastering Plus is the latest evolution of the original Phoenix compressor, refined for mastering applications with precision stepped controls and upgraded components throughout. The signal path and side chain are fully valve-based with no solid-state components, and the entire unit is point-to-point hand wired in England. Building on the Master Phoenix introduced in 2006, the Mastering Plus replaces the Gain and Threshold controls with Elma precision switches and the Attack and Release controls with Alpha switches—all Mullard and Siemens new-old-stock valves are used exclusively for low noise and long-term stability. Front-panel access to the meter zero trim controls and precise Omeg indented Output Level pots make stereo calibration and recall straightforward, and balanced inputs and outputs are provided by custom-made Sowter transformers. A Standby switch prolongs valve and capacitor life; a noted secondary characteristic of standby operation is that it produces an analogue tape-type distortion that some users find useful in its own right.

Key Features

• All-valve signal path and side chain — point-to-point hand wired in England — no solid-state components; fully valve-based compression and side chain circuits throughout
• Push-pull design — natural warm sound with high output level; the same topology that defines the original Phoenix character
• Soft-knee compression — subtle and natural-sounding at moderate settings; capable of heavier compression effects and harmonic saturation when pushed hard
• Elma switches for Gain and Threshold — precision stepped controls for fully repeatable settings essential in mastering recall
• Alpha switches for Attack and Release — stepped attack and release for consistent session-to-session recall
• Omeg indented pots for Output Level — fine, recallable control over output gain; also usable for lower-level operation
• All Mullard and Siemens NOS valves — selected exclusively for low noise and long-term stability
• Balanced ins and outs — custom-made Sowter transformers — professional balanced I/O; flat frequency response over the full audio range and beyond; very low phase shift and harmonic distortion
• Side chain bass cut switches — prevents low-frequency content from triggering compression; with stereo link engaged, the side chain operates at the average of the two switch positions, providing 5 effective frequency options in stereo mastering
• Stereo link — links both channels for mix bus compression
• Bypass switch per channel — removes all electronics from the signal path for accurate A/B comparison
• Standby switch — prolongs valve and capacitor life; audio still passes with standby on; when operated in standby, the unit produces an analogue tape-type distortion that some users find musically useful (unintentional, but noted)
• Front-panel meter zero trim access — trim controls situated between the two meters for easy calibration; both meters should read 0 when off standby and not compressing

Specifications

• Channels: Stereo (2)
• Compression Type: Variable mu; soft knee; push-pull design
• Signal Path: All-valve; no solid state; point-to-point hand wired
• Gain Control: Elma precision switch (stepped)
• Threshold Control: Elma precision switch (stepped)
• Attack Control: Alpha switch (stepped)
• Release Control: Alpha switch (stepped)
• Output Level: Omeg indented pot (per channel)
• Valves: Mullard and Siemens NOS (exclusively)
• I/O: Balanced; custom-made Sowter transformers
• Frequency Response: Flat over full audio range and beyond
• Side Chain Bass Cut: Switched per channel; 5 effective frequencies in stereo link mode
• Stereo Link: Yes
• Bypass: Per-channel switch (removes all electronics)
• Standby Switch: Yes (HT standby; audio passes; tape-type distortion characteristic in standby)
• Meter Zero Trim: Front-panel accessible (between the 2 meters)
• Construction: Point-to-point hand wired in England