Earlybird 2.2 manual
THERMIONIC
CULTURE
TheEarlybird 2.2
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.
It is not advisable to operate this equipment if all valves are not in
place and working, as voltages will rise and components may
overheat and fail.
©Thermionic Culture Ltd., September 2010
1
CONTENTS
Section
Page
1
Introduction
3
2
Controls
4
2.1
Function
4
2.2
Gain
4
2.3
Bass cut
4
2.4
Active lift
4
2.4.1
Top
5
2.4.2
Mid
5
2.4.3
Bass
5
2.5
+48V
5
2.6
Phase reverse
5
2.7
Output trim
6
3
Metering
7
4
Connections
8
4.1
Mic Input
8
4.2
Line Input
8
4.3
Pullet
8
4.4
Output
8
5
6
Operational suggestions
9
5.1
Impedance
9
5.2
PAD
9
5.3
Pullet
10
5.4
EQ
10
5.5
Mono mic-amp with Pullet EQ
11
Specification
©Thermionic Culture Ltd., September 2010
12
2
1
Introduction
The Earlybird 2.2 is a two channel all valve pre-amp
employing a balanced push-pull circuit, which as far as we
know, is unique in this application. The use of this type of
circuit gives very low noise and plenty of headroom with
minimal distortion. These factors coupled with a switchable
input impedance will mean the user can get a very natural
interpretation of whatever sound the microphone is picking
up, whether the mic is valve, ribbon, moving coil or FET.
After much dedicated development work in conjunction with
Brian Sowter, we have arrived at the pinnacle of audio
transformer design. Both the input and output transformers
have been optimized for use in our unique circuit. This
results in more headroom and lower distortion especially at
low frequencies.
The Earlybird 2.2 need not stand idle once the mixing
process has begun. The line input facility means that the
sonic characteristics and EQ facilities of the Earlybird 2.2
can be fully utilised on any mono or stereo signals that the
user feels may benefit from such enhancement. With this in
mind the Pullet acts as a perfect companion for precision mid
range EQ.
We believe that the Earlybird 2.2 is not only the finest micamp available for today's recording environment but
combined with its EQ and Pullet compatibility, the most
versatile.
©Thermionic Culture Ltd., September 2010
3
2
Controls
2.1
Function
This control selects the basic operating mode of the
Earlybird. The pre-amp can be aligned to operate as:
300Ω:-
A mic-amp with an input impedance of
300Ω
1200Ω:- A mic-amp with an input impedance of
1200Ω
PAD:A mic-amp with an 18dB attenuating pad in
front of its transformer.
LINE:A pre-amp that accepts line level signals
PULLET:- A pre-amp that provides the make-up gain
for the passive EQ network provided by the
Pullet in order to bring the signal back up to
line level.
2.2
Gain
This control selects the gain setting that the Earlybird
is operating at. The Gain is varied in four steps of 8dB.
i.e. 32dB to 60dB (mic), -8dB to 16dB (line).
2.3
Bass cut
The response is flat when this switch is fully anticlockwise. It acts as a HPF at 40Hz with a
12dB/octave slope, a little gentler at 100Hz and is a
shelving filter at 800 Hz.
2.4
Active lift
The three bands of active lift work in the negative
feedback loop. They are most effective at the first two
gain settings (36/-8 to 44/0), then less effective at 52/8
and almost out at maximum gain (60/16) as feedback
is reduced in the circuit to increase gain.
©Thermionic Culture Ltd., September 2010
4
2.5
2.4.1
Top
This
control uses
our award-winning
'Varislope' lift circuit where the lift is a nearly
flat "shelf" at low settings and as the control is
advanced
it
accentuates
the
higher
frequencies, resulting in a peak of 20dB at
10kHz (with gain set at 36 or 44dB).
2.4.2
Mid
A very broad lift peaking at either 800Hz or
2.5kHz depending on the position of the Mid
lift frequency selector switch. The maximum
lift available is 15dB.
2.4.3
Bass
Another 'Varislope' curve, where the lift starts
off quite high (2kHz) and the lower
frequencies gradually rise as the control is
advanced, giving a peak of 17dB at 50 Hz
when turned to maximum.
+48V
This switch will apply phantom power to the mic-in
sockets when in the down position.
2.6
Phase reverse
These switches will invert the phase of the signal in
the corresponding channel when in the down position.
©Thermionic Culture Ltd., September 2010
5
2.7
Output trim
These controls are reverse linear attenuators,
operating after all of the electronics. The full output of
the electronics is sent to the output plugs when the
controls are set to maximum. These controls can be
used as a ‘fine’ level adjustment or an output
attenuator so that the unit can be run ‘hot’ in order to
get some distortion without overloading the next piece
of equipment in the chain.
©Thermionic Culture Ltd., September 2010
6
3
Metering
The meters are a VU type, however they do have a
compressed scale above 0VU. This feature has been
applied to the meters because a mic-amp will naturally have
un-compressed signals passed through it. A signal like this,
on a normal VU scale, will tend to look as if there is either
too little level, or so much level that it is ‘off the scale’. As the
Earlybird has such a lot of headroom available before
distortion becomes a problem, we wanted the VU scale to be
useful when running the mic-amp ‘hot’. In this way the
meters can still display what is going on without simply
hitting the end stops at high level.
The Meters are aligned to measure the output of the
electronics (less 2dB) before the output trim controls. The
meters closely match the output of the unit after the output
trim when the controls are set to 8.5. When the controls are
at maximum add 2dB to the VU reading. When the output
controls are set below 8.5 the output of the unit will be lower
than is shown on the VU meter.
©Thermionic Culture Ltd., September 2010
7
4
Connections
There is a row of input and output sockets on the back of the
Earlybird, which allow it to be left permanently connected for
it’s various configurations.
4.1
Mic input
These XLR sockets are for connecting microphones to
the Earlybird. The 48-volt phantom power supply will
applied to these sockets only. The Mic settings on the
Function switch will all select these inputs.
4.2
Line input
These XLR sockets are to be used when connecting a
line level signal to the Earlybird. The Line setting on
the Function switch will select these inputs.
4.3
Pullet
These XLR sockets should be used when connecting
the Pullet to the Earlybird. The leads between the
Pullet and these sockets should be as short as
possible in order to avoid picking up any extraneous
noise due to the low signal levels at this point.
Thermionic Culture can supply leads of the correct
length if required.
4.4
Output
These XLR plugs are the signal output points for the
Earlybird.
©Thermionic Culture Ltd., September 2010
8
5
Operational suggestions
5.1
Impedance
The Earlybird has a switchable input impedance for its
mic-amp inputs. This control has a large effect on the
tone obtained from whatever microphone is being
used. Technically 1200Ω is a good impedance for
Neumann FET mics whilst 300Ω is a good impedance
for ribbon mics such as the Coles 4038. However we
have found that the impedance control can be used as
a creative tonal adjustment.
Using a Neumann U87 with the 1200Ω setting the mic
will sound very open with an extended top end
presented to the listener. If the 300Ω setting is used
with the same mic, the gain will increase slightly but
the top frequencies will become slightly degraded and
lower in level. To the ear the sound seems to become
slightly more aggressive with a mid range punch to it.
This kind of thing can make all the difference when
recording things like vocals. For example a gentle
vocal will sound big and open on the 1200Ω setting,
whereas a rock vocal will punch through the mix when
using the 300Ω setting.
Ribbon mics may well come into their own when using
the Earlybird with the 300Ω setting. The gain, top
frequency response, noise and distortion will all be
optimum in this case and the ribbon mic can be used
in situations that were not possible before, or they may
simply sound better than before.
5.2
PAD
The PAD control on the Earlybird should be used
when very high levels are coming from the mic being
used. For example a valve mic that is near to a guitar
amp or drum kit will give out a high output level. Using
©Thermionic Culture Ltd., September 2010
9
the PAD will stop distortion in the input transformers of
the Earlybird mic amp.
5.3
Pullet
Setting the Function control to Pullet will configure the
Earlybird to take its input signal from the Pullet
sockets on the back of the unit. This means that a line
level signal can be fed into the Pullet and then into the
Earlybird. The gain of the Earlybird should be set to
44/0 to give unity gain but it may be necessary to
reduce the gain if a large amount of mid boost is used
on the Pullet and the Active lift is being used too. This
is totally dependent on the preference of the user as a
bit of distortion may be what is needed. It’s worth
noting again that the leads connecting the Pullet to the
Earlybird should be as short as possible to avoid any
extraneous noise pick-up. Some 1-metre long leads
can be obtained from Thermionic Culture if needed.
5.4
EQ
The EQ section of the Earlybird is designed to be
useful in many situations:
The EQ can be used when the Earlybird is configured
as a mic-amp and provide some extremely useful
frequency lifting when recording from a large variety of
sources. The beauty of this EQ is that there is no harm
done at all to the signal by switching the EQ section,
set flat, into circuit. This is because the EQ works on
the feedback of the circuit, so the actual signal does
not pass through any more components than before.
In fact, any additional distortion is negligible until a
large amount of EQ is applied. This allows the user to
add EQ to the signal in a very purist manner. In reality
there are many situations in which a bit of EQ added
to a mic signal is necessary. Eg. Adding top to a close
mic’d snare or bottom end to a ‘one mic’ drum sound.
©Thermionic Culture Ltd., September 2010
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If the Earlybird is configured as a line amp then it can
be a very useful valve EQ. We have had very positive
feedback from users who like to EQ their electric
guitars with the Earlybird mid range on mix down.
There is no mid cut control but a little mid cut at 700800Hz can be achieved by setting Bass Cut to 800Hz
and Bass Lift to near max.
When using the Pullet, the EQ of the Earlybird
provides the necessary bass end control. The active
top and mid sections can also be used, in combination
with the facilities and sound of the passive Pullet EQ.
The sonic characteristics of both types of EQ together
give endless possibilities.
5.5
Mono mic-amp with Pullet EQ
The Earlybird can also be used in mono with the
Pullet, as a mic amp with fully implemented EQ. This
can be achieved by using E.B. CH1 as the mic-amp
then taking the signal from E.B. CH1 OUT, into Pullet
CH1 IN, from Pullet CH1 OUT into E.B. CH2 Pullet
IN. This arrangement makes the Earlybird / Pullet
combination a very versatile one.
©Thermionic Culture Ltd., September 2010
11
6
Specification
Included are the figures for noise, distortion and EQ. They
are all measured with the Earlybird set up for 44dB mic gain /
0 dB line gain and a 10kΩ load.
Input impedance
Mic
Pad
Line
Pullet
Output impedance
Maximum gain
Maximum output level (MOL)
Distortion (THD) @
1kHz
100Hz
Frequency response
±0.5dB
±1dB
Total noise, unweighted, 30kHz
filter
EQ, active controls @ max:
Bass
Mid
Top
Phase shift
HF
LF
Gain settings (dB)
Mic
Line
High pass filter (Hz)
Output trim
Input and output connectors
Valve complement
Pilot light bulb
Fuses
©Thermionic Culture Ltd., September 2010
300Ω or 1200Ω, switchable,
balanced
1.8kΩ
12.7kΩ
1.2kΩ
<300Ω
62dB
+33dBm (36V RMS)
0.005%
0.01%
11Hz to 26kHz
8Hz to 65kHz
114dB below MOL
[email protected]
[email protected] & 2.5kHz
[email protected]
16° (4.5%) @10kHz
0 within audible range
36, 44, 52 & 60dB
-8, 0, 8 & 16dB
0, 40, 100 & 800Hz
-18dB to 0dB reverse linear
attenuator
8x3 pin XLRs, wired balanced
2x12AX7LPS/ECC83/7025,
2x12AU7/ECC82/6189
24V/2.8W
115V: T1.25A
230V: T0.63A
12
Earlybird 2.2 Frequency response curves
25
15
Gain (dB)
5
10
100
1000
10000
100000
-5
Flat
Bass Cut 40Hz
Bass Cut 100Hz
Bass Cut 800Hz
Bass Cut 800Hz Bass Lift at '8.5'
Bass Lift at Max
Mid Lift 0.8kHz
Mid Lift 2.5kHz
Top Lift at '8'
Top Lift at Max
-15
-25
-35
f(Hz)
Thermionic Culture Ltd., Harlow, Essex, UK
Tel: +44 (0)1279 414770 Fax: +44 (0)1279 412233
www.thermionicculture.com
©Thermionic Culture Ltd., September 2010. Printed in UK.
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