User manual MARSHALL AMPLIFIER LIMITED EDITION JTM45 100 DUAL OUTPUT 100W SUPER LEAD HEAD

[. . . ] Slight circuit variations were apparent between models due to Marshall's ongoing development of the 100 watt amplifier at that time. The way the three ECC83s (labelled V1, V2 & V3 in the photo) in the pre-amp are utilised is as follows ­ V1 is the pre-amp gain stage for the High Treble and Normal channels. Each half of the valve (the ECC83 is a dualtriode which means it is literally two triode valves in one) acts as a dedicated gain/input buffer stage for each channel. V2 is common to both channels which are passively summed at the input of this valve. The first half of V2 acts as a second gain stage, which boosts the signal further and directly drives the second half of the valve which is configured as a cathode follower ­ a unity voltage gain device which acts as a high input impedance buffer, providing a low output impedance to drive the pre-amp's passive tone network. ENGLISH V3 is the amplifier's phase invertor and sits at the very end of the pre-amp section's tone circuit. V3 divides its input signal into two separate output signals that are inverted with respect to each other ­ hence the name `phase invertor' (a. k. a. `phase splitter'). The two resulting signals are then fed to the push-pull power output stage of the amplifier. The speaker cabinets in the Anniversary Stack, 812T40 and 812B40, have been designed to recreate the majestic look of the original 8x12s when stacked. We could, of course, have replicated the 8x12 but in consideration to your back (and your roadies!) we decided that dividing it into two 4x12s was much more sensible!Just like the original 8x12, both cabs are loaded with Celestion's highly celebrated T652 Alnico Speakers. The angled top cabinet also features a semi-open back, just like the genuine 8x12 reference we took our dimensions from. Components: Wherever and whenever possible, we have gone back to the original manufacturers for all components to maintain the highest quality and to ensure maximum authenticity. The JTM45/100's organic, vibrant, sweetly distorted, harmonically rich and thick musical tone emanates from its power valves being driven into a dual 50 watt output stage. When `cranked, ' the JTM45/100 produces its own unique roar with an inspiring `punch you in the chest' clout. [. . . ] The Standby Switch is used in conjunction with the Power Switch (item 1) to 'warm up' the amplifier before use and to prolong the life of the output valves. When powering up the amplifier always engage the Power Switch first, leaving the Standby switch on 'Standby'. This allows the heater voltage to bring the valves to their correct operating temperature. After approximately two minutes the valves will have reached their correct operating temperature and the Standby Switch can be engaged, enabling the HT without 'shocking' cold valves. In order to prolong valve life, the Standby Switch alone should also be used to turn the amplifier on and off during breaks in a performance. Also, when switching off, always disengage the Standby Switch prior to the main Power Switch. This adjusts the top-end. Turning it clockwise increases the amount of high frequencies present in the sound, giving your guitar tone a brighter edge. 7. TREBLE CONTROL 2. STANDBY SWITCH Output Transformers: As already mentioned, the pair of output transformers used in the original JTM45/100s were supplied by Drake, as are those in your reissue. Fortunately Drake still had their original documentation intact after all of these years, a factor which obviously helped ensure that the reissues are 100% accurate. Power Supply: This circuit has the same exact filtering on the H. T. the B+ voltage) line as the original versions, a factor that contributes to the JTM45/100 having a unique, dynamic characteristic all of its own. Note: The following four controls - PRESENCE (item 4), BASS (item 5), MIDDLE (item 6) & TREBLE (item 7) - are all shared, meaning that they are common to both Channel I and Channel II. They are highly interactive and altering one control can change the way the others behave. For this reason, experimentation is recommended. This controls the overall output level of Channel I, turning it clockwise increases the volume. This channel is voiced for a higher treble response than Channel II, hence its 'High Treble' labelling. 8. LOUDNESS 1 Chassis: We are using a box-section chassis made from 16-gauge mild steel with butt-welded corner joints. The steel is also passivated giving lifelong resistance to corrosion. Front Panel: Extra thick, gold coloured Plexiglas (actually Perspex, causing some people to refer to it as `Perplexi'!), exactly as the original. Specific details pertaining to the front panel features can be found on page 5 of this manual. Rear Panel: Made from cream styrene with gold print, just like the original references. This controls the overall output level of Channel II, turning it clockwise increases the volume level. This channel is voiced for a 'normal', flatter response and is labelled as the 'Normal' channel. 9. However, due to the unique power amplifier output configuration, they are not in parallel, as are standard models. Please always ensure that the amplifier's output impedance selector is set correctly (see item 2) and ALWAYS ensure you use good quality speaker (non-screened) cables. NEVER use guitar (screened) cables. Because both Channels of the JTM45/100 have the same number of gain stages and are in phase with each other, it is possible to `jump' (a. k. a. `link' or `bridge') them together and use them both at the same time. Doing this enables you to expand upon the amp's tonal capabilities. 1. LOUDSPEAKER OUTPUTS The most common way of doing this is to plug your guitar into the top (high sensitivity) input of Channel I and then run a short `jumper' guitar cable (i. e. a screened cable) from Channel I's bottom (low sensitivity) input to the top (high sensitivity) input of Channel 2. Adjust both channel volumes (Loudness I & 2 controls) until the desired mix of tone is achieved. plugging your guitar into Channel II's top input and then running the `jumper' cable from Channel 2's bottom input to Channel I's top input. WARNING! [. . . ] MAINS FUSE Technical Specification JTM45/100 Head Power Output Weight Size 100W RMS 22 kg 740mm x 270mm x 210mm 812T40 & 812B40 Cabinets Power Handling (per cabinet) 100W RMS Weight - 812T40 36 kg Weight - 812B40 39 kg Size 754mm x 741mm x 355. 5mm EUROPE ONLY - Note: This equipment has been tested and found to comply with the requirements of the EMC Directive (Environments E1, E2 and E3 EN 55103-1/2) and the Low Voltage Directive in the E. U. EUROPE ONLY - Note: The Peak Inrush current for the JTM45/100 is 39 amps. 6 1x16 Ohm cabinet - Selectors on 16 Ohm. 2x16 Ohm cabinets - Both selectors on 16 Ohm. 2x8 Ohm cabinets - Both selectors on 8 Ohm. [. . . ]