Marshall Amplification EL84 20/20 Manual page 3

PLEASE READ THE FOLLOWING LIST CAREFULLY
A. ALWAYS fit a good quality mains plug conforming to the latest B.S.I. standards where necessary (UK only).
B. NEVER attempt to by-pass fuses or fit ones of the incorrect value.
C. NEVER attempt to replace fuses or valves with the amplifier connected to the mains.
D. DO NOT attempt to remove the amplifier chassis, there are no user serviceable parts.
E. ALWAYS have this equipment serviced or repaired by competent, qualified personnel.
F. NEVER use an amplifier in damp or wet conditions.
G. DO NOT switch the amplifier on without the loudspeaker connected.
H. ENSURE that any extension cabinets used are of the correct impedance.
I. WARNING: When fitted into a standard rack or flight case, ALWAYS ensure that the front and back of the
case are completely removed. For stand alone use, a clearance of 30cm is required at the top, back and sides.
J. PLEASE read this instruction manual carefully before switching on.
WARNING : This apparatus must be earthed.
Introduction
Models EL84 20/20, EL34 50/50 and EL34 100/100 stereo valve power amplifiers are the latest step forward in valve
rack technology from Marshall. Built as dedicated guitar system based units, they incorporate many features that are
both revolutionary and evolutionary. From stunning styling, through to the radical circuit design, these power amps are
in a sonic class of their own.
EL84 20/20
The EL84 20/20 is the latest all valve power amp from Marshall and utilises EL84 power valves to obtain that classic
british tone, famous since the birth of British rock guitar in the early sixties. Despite its compact size and modest power
rating, the 20/20 packs a big punch, both sonically and in terms of features. Carefully designed to maximise clean
headroom and also endowed with superb overload capability, the 20/20 is ideal for compact rack rigs, for both sessions
and club gigs alike. When miked up on larger concert stages it will provide pure valve tone with the minimum of stage
spill.
The remotely switchable deep switch can be used to alter the sonic character of your pre-amp patches to great effect.
Also the innovative valve line stage, at the input of each channel, helps to give true valve warmth to even the most sterile
sounding pre-amp. The EL84 20/20 is a compact powerhouse which can greatly enhance the tonal palette of any rack rig.
EL34 50/50 & EL34 100/100
With the EL34 50/50 and EL34 100/100 the specially designed Marshall 'Gold' front panel provides a deep recess in
which the controls are sited giving a smooth uncluttered finish, whilst allowing the controls to be set, with little fear of
accidental re-adjustment. The two power amp halves of your EL34 50/50 or EL34 100/100 are totally separate
'MonoBlocs', a feature that is normally only found on expensive valve hi-fi power amps. This means that the only
common electrical item (apart from when specifically cross linking inputs) is the mains supply and that nothing that
occurs to one power amp can sonically react with the other half. Also in the unlikely event of one side breaking down,
the other side will carry on working regardless.
Our constant research into valve amplifier technology has resulted in further circuit design improvements which
dramatically affect the overall feel and playing response of your Marshall valve power amp. These improvements
include Marshalls latest True Differential Inverter technology, which expands the capability of the phase splitter
(inverter). Put simply, the phase splitter takes the incoming signal and inverts half of it. This inverted half of the signal
forms the bottom half of the sound envelope and the non-inverted half forms the top half. The effect of T.D.I. technology
is to give a more defined spectrum of sound over a broader band width, without compromising the overdrive and
compression effects for which valve amplifiers are famed. This also allows more radical uses of feedback networks and
the incorporation of the 'voicing' switching found on each channel. These incredible 'voicing' options, which can be
remotely activated, can be used to greatly expand your pre-amps tone forming at the flick of a switch.
Mounting the Power Amp in a Rack
To allow the secure fastening of 19 inch rack units in a rack enclosure, a series of mounting holes are provided on the
front of the EL84 20/20 and on both the front and rear of the EL34 50/50 and EL34 100/100. As with all rack mount
products of substantial weight, such as the EL34 50/50 & 100/100, the rear of the unit must be supported as well as the
front, therefore suitable brackets should be obtained and fitted between the provided rear mountings and the rack case. It
should always be remembered that valve amplifiers generate a certain amount of heat, therefore they should never be
mounted, or used, in any situation without adequate airflow.
WARNING!
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