Marshall 1959 SLP - Pierre Schwartz

Evil Guitars







I bought this amp from lead vocalist Michael from the Danish heavy band called Alien Force in 1990, it was in a bad shape tube vice. Price approx $375.
Michael Joined me in Big Time as Lead vocalist 1988-1990.
The amp is completly original from build in 1969 witn "plexi front", except from the Groove Tubes (Groove Tubes Power GTEL34R Quartett no. 3944048 82,90 EUR) and the front Marshall logo (Accessories for Amps Marshall Logo gold, klein Logo, gold, klein no.3050069 9,00 EUR), which was changed in 2007. It's more than 40 year old, plays wonderfull with a power strike and bottom, that will blow you away............
A "plexi" Marshall is one from around 1965 through the middle of 1969.  What distinguishes "plexi" Marshalls from others is the material that the front (and sometimes back) panel is made from.  The "plexi" panel is a plastic called "perspex" that is clear with lettering and gold on the back surface.  It is mounted to the front of the amp chassis and becomes the front panel that the jacks and pots are mounted to.  The amps before the plexi models had either white panels or on some, lettering was screened to the aluminum chassis.  There are some JTM45s and JTM45/100 (the first production 100 watt heads) amps that have plexi front panels and a cream colored back panels.  Plexi does not mean see-through. (source 20th Century Guitar Magazine Anniversary Article By Mitch Colby)

Pictures of my amp serial SL/A 10209


Blue print avaiable here:

Marshall 1959 SLP Super Lead Plexi Guitar Amplifier Head
The Marshall 1959SLP 100 Watt Super Lead Plexiglas head of the late '60s/early '70s, as used by countless classic bands, reissued in all its glory. The 1959SLP has been in production since the late sixties but with various electrical and cosmetic changes happening along the way. The models produced in the late 1960s/early 1970s however, were the ones that most tone gurus regarded as the finest examples.
  • Output (RMS): 100W
  • Pre-amp Valves: 3 x ECC83
  • Power Amp Valves: 4 x EL34
  • EQ: 3-band
  • Presence Control
  • Dimensions (mm): 750 x 310 x 210
  • Weight (Kg): 20.5



Marshall Amplifier Date Codes

The newest models are incredibly easy to date (read on, if you aren't already aware of the current serial numbering system) but dating older amps (pre-1993) are slightly more involved. Here's the story so far…  

July 1969 - September 1992  

In July of '69, Marshall introduced their first date code system. To determine the year of manufacture, a letter of the alphabet was included in the serial number. Here's how it works:

A – 1969/1970       C – 1971               D – 1972               E – 1973

F – 1974               G – 1975               H – 1976               J – 1977

K – 1978               L – 1979               M – 1980               N – 1981

P – 1982               R – 1983               S – 1984               T – 1985

U – 1986               V – 1987               W – 1988              X – 1989

Y – 1990               Z – 1991/1992

“B” was skipped because “A” ran for 18 months and “I,” “O” and “Q” were also skipped because they looked too similar to numbers.

As a rule, the serial number is usually located on the back panel of the chassis but some amplifiers made between 1979 - 1980 had them on the front panel. Now, at this point you're probably wondering where exactly this letter can be found within the serial number. That's a very good question so here's the answer. From July 1969 to December 1983, the letter was put after the serial number. For example, let's say you found this stamped on the back panel:

SL/A  14532  D

What does it mean?  

SL/A = model number

12532 = serial number

D = Date code (1972)
















Tubes pre


12AT6, 12AT7 | Electronic Vacuum Tube Specifications

Tubes output

Groove tubes EL34 changed in 2005

Groove Tubes Power 4xGTEL34R Quartett no. 3944048 82,90 EUR

This Russian made pentode is standard issue on many UK amps and has great durability, although as with most Russian power tubes the break up is a bit harsh and they lack high end as compared to the true European models.Unique sound, slightly edgy distortion when pushed hard. Newly exclusive GT design, close copy of classic Mullard type with good power and flat tonal response.  The most reliable of all in this family.

Contact info: