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Building on the phenomenal success of The Fat Bustard summing mixer whose features include Attitude, EQ, stereo width, and of course a big fat sound. Fulfilling the demand for a similar warm sounding summing mixer with more channels at a lower price the Thermionic Culture Purple Bustard Summing Mixer was born.


This new unit utilizes the same input circuit and Attitude section as the Fat Bustard, using the same type twin triode valves.Instead of having EQs and Stereo Spread, etc., there is only the “AIR” control which works on the very high end. Because the unit contains no solid state in the audio path, the use of this control will enhance the sound with a lovely velvety sheen typical of the best all-valve equipment with none of the harshness found in some solid state units.


The output stage is very similar to that of The Fat Bustard, except that for reasons of space and heat, smaller double triodes are employed. All valves are “mil spec” NOS types. The max output level is still well above +20 dBv, adequate for any DAW.All inputs and outputs are on XLRs, with inputs “semi floating” and outputs unbalanced.

Front panel

There are 8 toggle switches to switch in pairs of channels, and 2 more toggles to switch channels 13,14,15 & 16 to make 4 mono channels. AIR, a rotary pot, ATTITUDE, a 6 position switch, and a matched pair of pots controlling output levels. There's a mains power switch and of course The Purple Bustard’s eyes light up and go bloodshot as the sound gets louder!


The frequency response goes well above and below audio range until the Attitude is set to at or near max, similarly other specs are practically the same as The Fat Bustard, except cross-talk, phase shift and signal to noise are slightly better as there is no eq. etc.

The Features

All valve 16 input summing mixer

Each pair of inputs has its own on/off switch

Inputs 13 to 16 can be switched to centre

Attitude control adds musical 2nd harmonics

Air control increases high top end without solid state harshness

Frequency response extends well above and below audio range

Easily enough output to drive your DAW and very low noise

All inputs are “semi-floating” on XLRs

Outputs are unbalanced

Shares the same natural warmth as the Fat Bustard

Extremely low distortion (< 0.1%) before Attitude is added


Thermionic Culture Purple Bustard Summing Mixer

  • Thermionic Culture Purple Bustard Summing Mixer
  • Updated Little Red Bustard with a similar warm sound and more channels
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