EL84 20/20 EL34 50/50 EL34 100/100 VALVE POWER AMPS ENGLISH From Jim Marshall I would like to thank you personally for selecting one of our stereo valve power amplifiers. Since 1962 the valve has played an incredibly important part in the development of the Marshall Sound and we have been dedicated to the design and manufacture of the world's finest valve powered amplification. We are well aware of the special relationship that has formed between the guitarist and the valve over the years, indeed, we have always actively sought to enhance the unique character of our valve amps in order to foster this relationship. When designing our EL84 20/20, EL34 50/50 and EL34 100/100 Power amps, our valve design experts utilised all the knowledge and skill at their disposal with just one thing in mind - improved performance! Their combination of traditional Marshall valve technology with new and innovative circuitry, has resulted in designs that are radically different in terms of both looks and performance. The quality of tone produced by these all valve power amps is truly remarkable and, by reflecting all that is best about Marshall, will become an essential part of any serious stereo rack guitar system. I strongly suggest that you read this handbook carefully before operating your new stereo valve power amplifier and wish you every success with it. Sincerely, 2 WARNING! 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. ENGLISH 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. 3 EL84 20/20 Front Panel Features LEVEL PRESENCE OFF OFF ENGLISH EL84 20/20 STEREO VALVE POWER AMPLIFIER 0 10 0 10 DEEP STANDBY POWER ON ON STANDBY POWER 1 2 3 4 5 6 7 1. Level sound. Controls Level or volume of the EL84 20/20. Adds brightness and top end bite to your 7. Power amplifier. On/Off Switch for mains power to the 2. Presence 3. Deep The Deep switch on the 20/20 affects the speaker damping. By depressing the Deep switch you will add more bottom end thud to your guitar sound. Similar to the difference between open and closed back cabinets. Indicates operating status of standby (see 6). 4. Standby LED 5. Power LED (see 7). Note: To prolong the life of the valves it is always advisable to switch on the Mains Power Switch (item 7) about 1 minute before switching on the Standby (item 6). This allows the valves to heat up to full working temperature before use. On switching off, the Standby should always be switched before the Power Switch. The standby facility is particularly useful live, where before playing and between sets, it allows you to keep the valves operating at a slightly reduced temperature but without any sound being produced. Indicates operating status of amp 6. Standby Controls the H.T. supply to the valves and allows the valves to remain heated when not in use. EL84 20/20 Rear Panel Features MAINS INPUT LEFT OUTPUTS RIGHT OUTPUTS 2x20 Watts RMS POWER OUTPUT INTO 8/16 REMOTE SWITCHING INPUTS 120V ~ 60Hz 220 WATTS 16 SPEAKER 8 LINE 16 SPEAKER 8 LINE DEEP LEFT RIGHT(MONO) 1 2 3 4 5 6 7 8 9 10 1. Mains Input Connects the amplifier to the mains power supply. Note: When the 20/20 is in use, speakers must be connected to both sides at all times. See Loading points Loading Points -The 20/20 delivers 2x20 Watts into 8 or 16 Ohms. -The 20/20 must have either an 8 Ohm or 16 Ohm speaker connected to either side. Under no circumstances should both the 8 and 16 Ohm sockets of the same side be used together. -The 20/20 must have speakers connected to both sides when in use. Left Outputs 2. 16 Ohm Jack Speaker jack for 16 Ohm speaker cabinet for left side of power amp. 3. 8 Ohm Jack Speaker jack for 8 Ohm speaker cabinet for left side of power amp. 4. Line Attenuated version of speaker signal giving whole tone of power stage. For connection to subsequent effects processor and larger power amp. Remote Switching 8. Deep In addition to the front panel, the Deep facility can be switched remotely by a footswitch or programmable device, such as an effects processor. It should be noted that this will override the front panel switch position. When 20/20 is in use, speakers must be connected to both sides at all times. See Loading points later. Note: Right Outputs 5. 16 Ohm Jack 6. 8 Ohm Jack 7. Line Speaker jack for 16 Ohm speaker cabinet for right side of power amp. Inputs 9. Left Takes the left input from a stereo pre-amp. Speaker jack for 8 Ohm speaker cabinet for right side of power amp. Attenuated version of speaker signal giving whole tone of power stage. For connection to subsequent effects processor and larger power amp. 10. Right (Mono) Takes the right input from a stereo pre-amp, or the mono input from a mono pre-amp. A mono input will drive both channels. 4 EL34 50/50 & EL35 100/100 Front Panel Features 17 ENGLISH A EL34 50/50 Dual MonoBloc Amplifier B 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1. Channel A mains power rocker switch Connects channel A to incoming mains supply. LED 3 indicates red when activated. 8. Channel A gain control Rotary control to set and balance the incoming signal level. 9. Channel B gain control 10. Channel B presence control 11. Channel B voice switch 12. Channel B voice LED 13. Channel B standby LED 14. Channel B mains LED 15. Channel B standby switch 16. Channel B mains switch Note! Channel A's notes also apply. 17. Front rack mount fixing holes. 2. Channel A standby switch Connects channel A's high voltage circuit to the power supply. LED 4 indicates green when activated. Note! To conserve valve life, standby switch 2 should remain off for at least 1 minute after powering up the amplifier. 3/4. Mains & standby LED's. 5. Voice B LED Indicates red when channel A's voicing option B is activated. 6. Channel A voice toggle switch Selects voice option A or B, this function is repeated on a remote switching jack on the rear panel (see rear panel functions). The switch should be in the B position for the remote switch to be operative. 7. Channel A presence control Rotary control to boost the upper mid to high frequency content of sound. Rear Panel Features 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1. Mains input socket Connects amplifier to incoming mains supply. 4. Channel B H.T. fuse Please see specifications for correct ratings. 2. Channel B mains fuse Please see specifications for correct ratings. 5. Channel A H.T. fuse Please see specifications for correct ratings. 3. Channel A mains fuse Please see specifications for correct ratings. 6. Channel B loudspeaker jacks Connects channel B to loudspeaker load - model EL34 50/50 - 50 watts RMS, model EL34 100/100 - 100 watts RMS. 5 ENGLISH 7. Channel B output impedance select 16 Ohm or 8 Ohm - it is important that your amplifier and loudspeaker load are correctly matched. Note! If 4 Ohm output is desired please consult your authorised Marshall agent. Note! Using 14 only connects input signal to both channels A & B for parallel mono operation. 15. Channel A link out jack Connects channel A input signal to further power amp inputs. 8. Channel A output impedance select (See 7 for notes). Valve Location Guide Rear Mounting Fixing Hole Rear Mounting Fixing Hole 9. Channel A loudspeaker jacks (See 6 for notes). 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