Thermionic Culture THE EARLYBIRD 4 4 User Manual

THERMIONIC

CULTURE

TheEarlybird 4

valve microphone pre-amplifier

OPERATING 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.

Please ensure that adequate ventilation is provided and that the
ventilation slots are not obstructed. When rack mounting this
equipment, a fan may be required to provide sufficient airflow.

©Thermionic Culture Ltd., July 2014 1

CONTENTS

Section Page

1 Introduction 3
2 Controls 4

2.1 Gain 4

2.2 Bass filter 4

2.3 Pad 4

2.4 Z

2.5 +48V 4

2.6 Phase reverse 4

2.7 Output trim 4

3 Metering 6
4 Operational suggestions 7
5 Specification 8

©Thermionic Culture Ltd., July 2014 2

1 Introduction

The Earlybird 4 is a four-channel mic-amp employing a
balanced push-pull all valve circuit, which as far as we know,
is unique in this application. The use of this type of circuit
gives seriously low noise, plenty of headroom and means a
very natural interpretation of whatever sound the microphone
is picking up, whether the mic is valve, dynamic or FET.

The Earlybird 4 mic amps are improved versions of the
Earlybird 1 and 2 series. They have improved Sowter input
and output transformers and traditional point-to-point hand
wiring by experts, eliminating the (slight) performance
degradation occurring when using circuit boards. The phase
shift is therefore very small and the distortion so low as to be
almost unmeasurable, especially in the mid range at the
most used gain settings. There is a natural warmth to the
sound but there is no compromising the frequency response,
and of course no solid state in the audio chain so no
“hardening” of the sound.

The Earlybird 4 should be considered as probably the
best microphone amplifier ever made.

“It’s like connecting a wire with gain to a microphone”.

©Thermionic Culture Ltd., July 2014 3