User manual MARSHALL AMPLIFIER 1959HW

[. . . ] Where relevant, specific details concerning these `deviations', and others, are inserted into the text labelled as `Tonal Notes'. As you can see from its front panel layout, the 1959HW is an extremely straightforward amplifier. Its two channels - Channel I and Channel II - each have two inputs (High and Low sensitivity) and separate Volume controls, while sharing the amplifier's four tone controls: Presence, Bass, Middle and Treble. Like all Marshall, all-valve amplifiers, the 1959 sounds at its very best when turned up full - and because of its conservative power rating and astonishing projection, is a formidable live amplifier in even the largest of venues. [. . . ] The cathode follower is a unity gain device which acts as a buffer, providing a low impedance signal to drive the tone network. Tonal Note 1: The second gain stage of the 1969 circuit we've faithfully reproduced boasts an extra cathode bypass capacitor which boosts upper-mids and top-end. This device divides the signal into two halves that are 180 degree out-of-phase with each other, and then feed the 1959's push-pull output stage. Mains (Power) Transformer: While the original transformer is large, the custom-made Dagnall reissue has been made even larger in order to satisfy strict, current-day safety legislation. Just like the original, the re-issue transformer is what is called a `drop through, half-shroud', which sits horizontally as opposed to vertically. As with the output transformer, we went to great lengths to ensure that its performance mirrors that of the original, paying particular attention to exactly replicating an effect called `regulation' - which is the way that the voltage from the transformer that feeds the valve circuitry varies according to load. In terms of the concentric design and performance, this transformer embodies the performance of the 1203-80 original specification first drawn up for us by Drake in February 1967. Due to the aforementioned modern legislations, the reissue is 3". Tonal Note 4: This circuit has the same filtering on the H. T. the B+ voltage) line as later versions, a factor that contributes to the 1959HW having a tighter sound than earlier versions. Note: The 1959HW incorporates 47nF/630V capacitors fitted in parallel with each of the four diodes in the bridge rectifier circuit. These are present for today's approval requirements that necessitate a reduction in electrical interference that may be generated and put back on the mains electricity supply. The addition of these capacitors has no sonic impact. 2 3 Chassis: We are using a box-section chassis made from 16 gauge mild steel with butt-welded corner joints. Our original chassis has a lot of extra holes drilled in it that weren't used. No doubt these existed because the same exact chassis was also used for other products made at the time. The most noticeable `extra hole' is one on top for a fourth ECC83 and on our reference unit, this particular hole has been covered up with a disc of steel that's been riveted into the two screw holes that would have been used to secure the valve holder, were it there. After approximately two minutes the valves will have reached the correct operating temperature and the Standby Switch can be engaged. 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. 8. VOLUME I This controls the overall output level of Channel I, turning it clockwise increases the volume. Tonal Note 5: The value of the capacitor across Volume I is 0. 005µF. This rather large value makes this channel aggressive and bright at relatively low settings. Many players bridge (see page 6 for details) Channels I and II (which has a darker, less aggressive tone) in order to have more control over their overall tone. Many earlier versions of the 1959 (from 1965 to 1967) used a 100pf capacitor across Volume I which gives a less aggressive sound at all volume levels less than 8. 3. [. . . ] 1) The `reverse' is also possible ­ namely plugging your guitar into Channel II's top input and then running the `jumper' cable from Channel II's bottom input to Channel I's top input. This less common approach can yield some interesting tonal variations. MAINS INPUT Your amp is provided with a detachable mains (power) lead, which is connected here. The specific mains input voltage rating that your amplifier has been built for is indicated on the back panel. [. . . ]