Part from the sleek new J.C.M. 800 styling, which places the controls on the full width fascia panel, offering much improved use and vision, there have been other important developments. By using newly developed loudspeakers, these Combos have been given a new depth of sound, without losing the smooth overload characteristics of the previous model. Also, treble and presence controls have been redesigned to give greater swing and less interaction with the rest of the tone network.
The Combos feature the original Marshall Master Volume circuitry, to enable the musician to reproduce the classic valve overdrive sound at any volume level. By varying the preamp volume and master volume controls, the output can be varied from a clean crisp sound to a rich overdrive sound. Exactly as model 2104 featured two inputs of different gain, so too with the new 4010 and 4104, both these channels mix into the newly modified tone circuitry of treble, middle and bass. Model 4010 features a single 65 watt high sensitivity speaker; and model 4104, though only slightly larger; has two of the same units to give greater projection of sound where required.