Thermionic Culture THE FAT BUSTARD II 12 User Manual

WARNING

For your personal safety, please read this operating manual
and warning thoroughly before using the equipment.

This unit must be installed in such a manner that operator
access to the mains plug is maintained. Where the product is
to be rack mounted, this may be achieved by having access to
the disconnection device for the whole rack.

To reduce the risk of electric shock, it is essential that the unit
is disconnected from the mains supply before removing the
cover.

Please also note that the power supply capacitors within this
unit can remain charged even after the mains supply has been
disconnected. It is essential that these capacitors are
discharged after the mains supply has been disconnected and
the covers have been removed.

In the event that this unit has been dropped or has suffered an
impact, an electrical safety test must be carried out before
reconnection to the mains supply.

This equipment is not intended for use in explosion hazard
environments. It must be used and stored in studio conditions,
such that the ambient relative humidity does not exceed 80%,
nor is the temperature to be allowed to drop to a level, which
would cause dew point to be reached.

The Fat Bustard gets hot! Please ensure that adequate
ventilation is provided and that the ventilation slots are not
obstructed. When rack mounting this equipment, mount it at
the top of the rack, or if there is equipment above it, leave an
air gap of 1U ( 1.75”) for heat to escape. A fan may be
required to provide sufficient airflow. Failure to observe these
precautions may result in damage occurring to the equipment
above and/or to the Fat Bustard.

©Thermionic Culture Ltd, May 2011 1

CONTENTS

Section Page
1 Introduction 3

2 Controls 4

2.1 Attitude 4

2.2 EQ section 4

2.3 Stereo width section 5

2.4 Stereo spread 5

2.5 Bandwidth 5

2.6 Bass to centre 6

2.7 Balance 6

2.8 Output level 6

2.9 Monitor 6

3 Installation Hints 7

3.1 Installation 7

3.2 Power 7

3.3 Inputs 7

3.4 Outputs 7

3.5 Audio Connections 7

3.6 Tips 8

4 Operational Hints 9
5 Inputs and Outputs 10
6 Servicing and Maintenance 11

6.1 Valves 11

6.2 Operating voltage / Fuse 11

7 Specification 12

© Thermionic Culture Ltd, May 2011 2

1 Introduction

The Fat Bustard is a passive input summing mixer that has all
valve summing and output stages. There are 12 input channels
and 2 auxiliary inputs. Included in the output stage are facilities
for stereo EQ, gain, distortion and also control of the stereo /
mono balance over different frequencies. These features are all
tried & tested and are felt to be useful and unique to what the
Fat Bustard offers and what it can be used to achieve.

The Fat Bustard owes its sound largely to the unusual choice of
valves used. The summing / EQ amplifier uses 5965 valves,
only used in audio applications by Fairchild before now. These
excellent valves give smoothness and fatness to the sound. The
output amplifier uses 6SN7 valves. These large output valves
give a huge amount of headroom and a tough punchy
character. The stereo width is controlled by a 12AU7 valve
giving a wide spectrum to the sound.

The Fat Bustard has been left with unbalanced inputs and
output as standard because, after much experimentation, the
sound of the unit was preferred this way.

© Thermionic Culture Ltd, May 2011 3

2 Controls

2.1 Attitude

The Attitude control has the same effect as found in
Thermionic Culture’s Rooster. At low settings (1 is low,
Max is high) the distortion is kept to a minimum and the
frequency response of the unit is very flat. At higher
settings the distortion increases and the frequency
response changes, tending to become less linear at high
frequencies.
At setting 1 on the attitude control the summing amplifier is
working at unity( 0dB ) gain. As the Attitude control is
increased the gain rises to +14dB at the max setting.

2.2 EQ section

The EQ section comprises a Bass lift, Top lift, Bass cut and
Top cut.

The Bass lift and Top lift utilise Thermionic Culture’s own
varislope EQ curves where:-

The Bass lift curve starts to rise at 2kHz at low settings

and at high settings the curve peaks at 50Hz.;

The Top lift curve starts to rise at 800Hz at low settings

and then gives a peak at 10kHz at high settings.

The Bass cut is a stepped switch control. Positions 1 to 3

give a 6dB / octave High pass filter rising in frequency as
the control is increased. Then positions 4 to 6 give a
shelving filter that begins to act higher in frequency as the
control is increased. This is intended to be used with the
Bass lift control, much like classic passive valve EQ
designs whereby a bass cut that acts slightly higher than
the bass lift will give a mid cut, then a bass lift.

© Thermionic Culture Ltd, May 2011 4