Rack Valve Power Amps Handbook
Contents
1. 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 PEAKER o 1 Mains Input Connects the amplifier to the mains power supply 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 Lin Attenuated version of speaker signal giving whole tone of power stage For connection to subsequent effects processor and larger power amp Note When 20 20 is in use speakers must be connected to both sides at all times See Loading points later Right Outputs 5 16 Ohm Jack Speaker jack for 16 Ohm speaker cabinet for right side of power amp 6 8 Ohm Jack Speaker jack for 8 Ohm speaker cabinet for right side of power amp 7 Line Attenuated version of speaker signal giving whole tone of power stage For connection to subsequent effects processor and larger power amp rete 20 20 7 Power On Off Switch for mains power to the amplifier Note To prolong the life of the valves it is always advisable to switch on the Mains Power Switch item 7 about 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 w2. 0V Consult amp rating plate or dealer Frequency 50 or 60 Hz 50 or 60 Hz Consult amp rating plate or dealer Mains fuses T3 15A 115V T4A 115V Per channel T1 6A 230V T2A 230V Per channel H T Fuses T315 mA TIA Per channel Output Power SOW RMS 100W RMS At clipping per channel Output Impedance 8 or 16 Ohm 8 or 16 Ohm Consult dealer for 4 Ohm Input sensitivity OdB OdB Input impedance 20KQ 20KQ Output valve 2 x EL34 4 x EL34 Per channel Phase inverter 1 x ECC81 12 AT7 1 x ECC81 12 AT7 Per channel Pre Driver 1 x ECC83 12 AX7 1 x ECC83 12 AX7 Per channel
3. 4 100 100 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 a
4. Valve Power Amps EL84 20 20 EL34 50 50 amp EL34 100 100 Marshall Amplification plc Denbigh Road Bletchley Milton Keynes MK1 1DQ England Tel 01908 375411 Fax 01908 376118 Web Site http www marshallamps com Whilst the information contained herein is correct at the time of publication due to our policy of constant improvement and development Marshall Amplification plc reserve the right to alter specifications without prior notice J an 99 Handbook 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
5. 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 amp EL34 100 100 With the EL34 50 50 and EL3
6. d remain off for at least 1 minute after powering up the amplifier 3 4 Mains amp 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 contro Rotary control to boost the upper mid to high frequency content of sound Rear Panel Features 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 1 Mains input socket Connects amplifier to incoming mains supply 2 Channel B mains fuse Please see specifications for correct ratings 3 Channel A mains fuse Please see specifications for correct ratings 4 4 Channel B H T fuse Please see specifications for correct ratings 5 Channel A H T 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 7 Channel B out
7. here before playing and between sets it allows you to keep the valves operating at a slightly reduced temperature but without any sound being produced REMOTE SWITCHING OMe No Ro No No MoM oN TS 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 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 Inputs 9 Left Takes the left input from a stereo pre 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 3 EL34 50 50 amp EL34 100 100 Front Panel Features 1 Channel A mains power rocker switch Connects channel A to incoming mains supply LED 3 indicates red when activated 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 shoul
8. lso 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 amp 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 2 EL84 20 20 Front Panel Features 66 1 Level Controls Level or volume of the EL84 20 20 2 Presence Adds brightness and top end bite to your sound 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 4 Standby LED Indicates operating status of standby see 6 5 Power LED Indicates operating status of amp see 7
9. put 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 8 Channel A output impedance select See 7 for notes 9 Channel A loudspeaker jacks See 6 for notes 10 11 Remote voicing switching jacks 10 operates on channel B 11 operates on channel A Short to ground function Using jack 11 only links channel A amp B switching functions for simultaneous use 12 Channel B link out jack Connects channel B input signal to further power amp inputs Note Using 14 only connects input signal to both channels A amp B for parallel mono operation 15 Channel A link out jack Connects channel A input signal to further power amp inputs Valve Location Guide Rear Mounting Fixing Hole OUTPUT TRANSFORMER MAINS TRANSFORMER Not Fitted To EL34 50 50 Rear Mounting Fixing Hole gt OUTPUT TRANSFORMER MAINS TRANSFORMER ECC81 ECC83 ECC83 13 Channel B input jack Accepts input from pre 12AT7 12AX7 12AX7 amp x r FRONT 14 Channel A input jack Accepts input from pre amp Specification Chart Parameter EL34 50 50 EL34 100 100 Notes Size 19 3U x 331mm deep 19 3U x 331mm deep The unit must be supported at the rear when mounted in a rack Weight 29 5 kg 34 5 kg Power input 350 watts 700 watts Voltage Input 115V or 230V 115V or 23
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