The History of: 1959SLP ‘Plexi’


The History of: 1959SLP ‘Plexi’

Looking back at one of the most iconic tones in rock history - the 1959SLP 'Plexi'

In over 50 years of Marshall, only a select handful of amps can come close to the legendary status of the ‘Plexi’ amplifiers. Its popularity and heritage has stood the test of time, and it’s why they are still replicated and produced today. The 1959SLP 100 Watt ‘Plexi’ is made to the same high standards since its introduction.

The journey to the ‘Plexi’ began in 1966 when the JTM50 was produced. This amplifier was using EL34 valves instead of the KT66s which were commonly used in Marshall amplifiers before this time. Jim Marshall himself was then contacted by Pete Townshend asking for a louder amplifier, Pete repeatedly asked for bigger and the Marshall team delivered. The prototype held four KT66 valves with two 50 Watt transformers as no 100 Watt transformer existed at the time. It then became noticeable that the sonic range of this amp was quite different to anything that had been produced before, this became even more apparent when Marshall began to use 100 Watt output transformers for the first production models in late 1965. In 1967, the KT66 valves were replaced with EL34’s, now synonymous with traditional Marshall growl and bite.

The look and aesthetic of the ‘Plexi’ amplifiers are arguably one of the most defining features. The name originates from its shiny, Plexiglas panel, commonly used on Marshall amps during 1965-1969. Although many amps are referred to as ‘Plexi’s’ The 100 Watt Super lead (Model number 1959) is most common of them all.

The popularity for the 100 Watt amp grew and grew through the late sixties. Primarily for two reasons, firstly due to the sheer volume. PA systems were still in early-production days and guitarists had to rely on the sheer power of their amplifiers to be heard in large venues. Secondly due to the power and tone of the amplifier, particularly the 68 specification amps (EL34 valves, dual rectifiers and a single output transformer) being used by Jimi Hendrix, Eddie Van Halen, Cream and of course, The Who. This created huge amounts of exposure and demand for the amp and it soon became an icon, with it’s legendary ‘Plexi sound’ that has been synonymous with rock music for decades.

Since its glory years the ‘Plexi’ has been reintroduced as part of the Vintage Re-issue series, and also in the Handwired Series. Replicating the amp to every detail with absolute tonal authenticity. We proudly built a replica so exact that it’s sonically impossible to tell the difference. To ensure modern versatility we also added a Series FX Loop with a True Bypass switch feature.

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