Thermionic Culture Purple Bustard All-Valve Stereo Summing Mixer

The Thermionic Culture Purple Bustard is a 16-input all-valve stereo summing mixer that shares its input circuit and Attitude harmonic distortion section with the Fat Bustard, at a more accessible price point and with a higher channel count. The audio path contains no solid-state components; all channel pairs are switched in at the front panel, and the summing and output stages use the same type of twin triode valves as the Fat Bustard, voiced with the same semi-floating input and unbalanced output topology. Where the Fat Bustard provides varislope EQ, stereo spread, and Bass to Centre controls, the Purple Bustard streamlines to a single AIR control for very high-end enhancement—delivering a characteristically velvety clarity that solid-state designs cannot replicate. Maximum output level is well above +20dBV, and a separate transformer balancing box with two Sowter transformers is available for installations requiring balanced outputs.

Key Features

• 16 inputs, all-valve signal path — 8 toggle switches engage pairs of stereo channels; 2 additional toggles configure channels 13–16 as 4 mono channels; no solid state in the audio path
• Same input circuit and Attitude section as the Fat Bustard — twin triode valves throughout; consistent summing character and harmonic response; semi-floating inputs, unbalanced XLR outputs
• AIR control — rotary pot; adds high-end clarity with the velvety character unique to all-valve designs; no harshness found in solid-state equivalents
• Attitude control — 6-position switch; adds 2nd harmonic content to the summing stage, from subtle musical warmth at lower positions to more aggressive character at higher positions
• Matched output level pots — a pair of matched pots control output level; max output well above +20dBV
• Mil-spec NOS valves throughout — all valves are military-specification new-old-stock types for long-term reliability and consistent performance
• Optional Sowter transformer balancing box — available at additional cost for installations requiring balanced outputs; contains 2 custom Sowter transformers

Specifications

• Inputs: 16 (8 stereo pairs via toggle switches; channels 13–16 configurable as 4 mono channels)
• Circuit Type: All-valve; no solid state in audio path
• Valve Types: Twin triodes (mil-spec NOS)
• Input Type: Semi-floating
• Outputs: Unbalanced; XLR
• Max Output Level: Above +20dBV
• AIR Control: Rotary pot (high-end clarity)
• Attitude Control: 6-position switch (2nd harmonic; summing stage)
• Output Level: Matched pot pair
• Optional: Transformer balancing box (2 × Sowter)
• Construction: Handcrafted in England