Each amplifier chassis is constructed from a minimum of 16 S.W.G. steel, precision cut, punched, bent and seam-welded to form a substantial, rigid foundation strong enough to take all the knocks of the road. Industrial grade cadmium passivating ensures many years of rust-free operation.

All electronic components are selected and tested to out perform their required functions, and the electrical hardware, such as switches, selectors, etc., comply to most international safety standards to ensure the user is safe from the risk of electric shock. The same applies to both the mains and output transformer, that are designed and built to withstand full output for hour upon hour. To complete the electrical specification all valves are selected from the finest grades available. Once assembled and wired, using both hand and machine techniques, each chassis is fully tested by the team of electronic engineers.

After testing and adjusting, each chassis is assembled into cabinets that are manufactured to an equal standard as the chassis. Each cabinet is made from finest quality birch ply, corner locked and r.f. bonded for immense strength and longevity. After the protective and decorative RV.C. covering is bonded and stretched onto the cabinet, A.B.S. corner protectors and air vents are riveted in position, and the heavy-duty strap handle and shock absorbing feet are screwed on.

A process of constant development work and a keen awareness of the requirements of the market piece, have resulted in the design and manufacture of a number of new amplifiers, beginning with the now famous 2000,2001 professional series. The success of these models, with their twin channel formats and versatile facilities, led in turn, to the production of the equally successful 5Ow Combo model 4210. To complete this line of development, two new heads have been produced which, although based closely on the Combo 4210, have been modified to accommodate the requirements of high powered stage loudspeaker stacks.

The preamplifier section has a single input, which is then split between the normal channel and the boost channel, these are footswitch selectable, hence the terminology "Split Channel". The normal' channel has volume, treble and bass controls, offering a wide range of sounds and is aimed at being the clean or rhythm channel. The 'boost' channel has an L.E.D. indicator to show selection and features gain, volume, treble, middle and bass controls. This is aimed at being the 'dirty' or lead channel and, as such, offers the player the facility of long, controllable sustain with the sound quality that has made Marshall the big name in guitar amplification.

Both channels are fed into the 'master' section that contains the footswitch-controlled Hammond reverb, presence control, effects send and return sockets, and the 'master volume' control that adjusts the apparent output power of the amplifier.

The output stage of each amplifier features either 50 watts or 100 watts of Marshall power and contains the usual Marshall items of selectable mains voltage and output impedance, fuse-holders etc., enabling the amplifier to be used world-wide with almost any loudspeaker configuration. Also on the output stage, is a frequency compensated D.I. socket and volume control to facilitate the ease of slaving or recording, yet maintaining the sound quality projected by Marshall loudspeaker systems.