A Summing Mixer With Attitude

The Thermionic Culture FAT BUSTARD MKII is an all valve passive input summing mixer. It has 14 inputs with 4 stereo inputs, 4 mono pan-able inputs and 2 ‘Aux’ inputs with a pan switch. The Fat Bustard is unique in it’s exceptional sound quality and also the extra degree of control and processing it offers over the stereo mix output. The mk II version is now the standard production model and it has been upgraded to include a monitor output with level control.

Much of the attractive sound provided by the Fat Bustard is down to the choice of valves used. The summing in the Thermionic Culture FAT BUSTARD MKII is done by a pair of 5965 valves and the output stage uses a pair of 6SN7 valves. This combination provides a very large amount of headroom and a unique smooth sounding response. It’s also worth noting that the unit has “semi-floating” inputs and unbalanced outputs. This was a decision made at the design stage purely because the unit sounded better this way and performed excellently when connected for use in all situations.

The Thermionic Culture FAT BUSTARD MKII employs our unique “varislope” curves for top and bass lift. As the control is turned up, the peak frequency of the curve becomes more extreme so as to add heavier bass/brilliant top – without the hardness found in solid state eqs. The bass and top cuts provide a variety of options to tailor the sound – too many to list here. They are of course independent of the lifts. All controls affect both stereo channels equally.

Attitude, Bass Lift, and Variable Stereo Image

The ‘Attitude’ control is the next to control the sound of the mix.This switched control gradually increases the amount of harmonic distortion in the stereo summing stage. It is relatively subtle (at least in the lower positions) to provide just the right amount of 2nd harmonic content for a stereo mix. At high positions the mix can be quite aggressive.

The stereo spread control allows the stereo to be widened by a continuous amount over a selectable frequency range.

The ‘Spread filter’ control allows the frequency above which widening occurs to be selected from full band widening to only widening above 5KHz. Again, this control can be used to vary the tone of the stereo mix as well as the stereo width. Along with stereo widening at higher frequencies.

The ‘Bass to Centre’ control allows bass frequencies in the stereo mix to be summed to mono for 2 different low frequency ranges, plus there is a setting for all frequencies to mono.

A Stereo ‘balance’ control and rotary 31 position ELMA switch for ‘Output level’ give full control over output levels.

The ‘Monitor level’ control, int/ext switch and extra outputs provide a useful way to connect and control monitors to the Fat Bustard. Especially useful when the Fat Bustard is the only mixer being used. If this is not a requirement then the int/ext switch in conjunction with the monitor outputs can be used to provide an insert in/out switch.

Thermionic Culture FAT BUSTARD MKII Product Specifications

Input impedance: 10kΩ (dependent upon channel and setting), unbalanced Output impedance: 600Ω unbalanced Monitor: 5kΩ unbalanced Gain (ch. 1-8): 0 at Attitude 1, +11dB at max attitude Maximum Output level: +25dBU Distortion: (at Attitude 1) 0.015% +8dBm output (at Attitude 3) 0.25% (at max. attitude) ≥1% (dependent on how hard valves are driven) Signal to noise: at least 100dB below MOL at Att.1 (IEC weighted) Freq. response (±1dB): 16Hz to 40kHz (at Attitude 1) Max bass lift +10dB @ 50Hz Max top lift: +12db @ 12kHz Phase shift (10kHz): (at Att.1), 7% (26°) with EQ flat (at Att. 4), 10% (36°) Crosstalk: 59dB @ 1kHz, 44dB @ 10kHz. (average at Att. 1 & 2) Crosstalk will increase at high attitude settings and when stereo spread and/or bass to centre controls are used.

For more information visit: http://www.thermionicculture.com/