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Marshall Valve Amps


Superleads (Marshall Mk II, heads):

1959 (100W) and 1987 (50W) are the two different "superlead" models. They

were introduced in 1965 and are still being made as í69 reissues. Originally

made with KT66 power tubes (1965) but soon they were replaced by EL34s

(1966). The superleads are easy to recognize with their four input-/no

master volume-design. The amps feature two channels (two inputs for each,

the inputs are wired so that they can be used to connect both channels, thus

giving you two different sounds in one, and the level of each controllable

with a volume), bright and normal, individual volumes for each channel and a

standard 4-band EQ. The sound is very "rock", and very wanted. With the lack

of a master volume, the amps rely on power tube distortion. This phenomenon

comes with a price, and the price is volume. And when I say volume, I mean

volume. A cranked 100W amp is VERY LOUD, therefore power attenuators are

often used to reduce the level from stupidly loud to extremely loud. An

original 1965-68 "plexi" (the term "plexi" is used due to the fact that the

amps had gold-painted plexiglas panels during that era) head might not be

very easy to find, and if you find one donít expect it to be cheap, but

superleads were made both as JMPs (in the 70s), JCM800s (in the 80s) and

reissues (today) and you should be able to find one used.

Tone Tips <tonetip.htm>


Plexi Information:

Years are 1965 to 1969, later in Europe. Three phases within the Plexi era:

(dates are approximate)

(mid 65-66) - block-lettered Marshall logo, JTM45/Mk II front panel legend,

aluminum chassis, KT66/640vA, 3" power transformer, 2" output transformer,

no external filter caps. (67-mid 68) - gold script Marshall logo, reverse

JTM front panel legend, steel chassis, EL34/460vA, 2" or 3" power

transformer, 1.75" output transformer, one external filter cap. (mid 68-mid

69) - gold script Marshall logo, JMP front panel legend, steel chassis,

EL34/500vA, 2" power transformer, 1.75" output transformer, six external

filter caps.


JMP series (heads and 2x12" combos):

In 1976 Marshall introduced the master volume amps (2203 (100W) and 2204

(50W)). With the master volume, the amps no longer had to be cranked to

distort. However, no tube amp will sound good at low volumes and these ones

are certainly no exceptions. The amps feature two inputs (high/low), preamp-

and master volume controls plus the standard Marshall 4-band EQ (treble,

middle, bass, presence). The superleads (1959 and 1987) were also made in

the JMP series. Identical to the originals except for the cabinet. All four

models (2203, 2204, 1959 and 1987) were also made as 2x12" combos (2103,

2104, 2159 and 2187). The sound is still classic rock and with a humbucker

loaded guitar and one of these, youíll have no problem grinding like a



JCM 800 master volume:

The JCM 800 master volume heads also have the model numbers 2203 and 2204

but are not identical to the JMPs. These amps have more gain than the JMPs

and this is partially due to a solid state clipping-circuit that was added

for this sole purpose. Some tube-fanatics consider this to be a work of

Satan and refuse to play JCM 800s. Being a work of Satan or not, the Mk II

master volumes still provide a sound that lots of people love. The sound is

quite dark and barky with an accentuated upper midrange, so if you're

looking for the scooped-mid Metallica sound, look elsewhere or buy an EQ and

a distortion pedal. These are no-nonsense machines for more classic rock

sounds. They can indeed be criticized for having basically just one sound,

but what a sound! Lots of people consider that sound to be THE sound...

JCM 800 superleads:

Basically identical to the original superleads but fitted in the modern bold


JCM 800 split channels:

Being the first Marshall with channel switching capabilities, the split

channel amps (heads: 2205 (50W) and 2210 (100W)) became very popular for

their versatility. The clean channel is by no means clean in the real

essence of the word, but to the early 80s Marshall devotees it was something

completely new. The overdrive channel sounds a lot like the master volumesí

and is clearly where these amps excel. Also fitted with a reverb (not

indiviual for each channel) and an FX loop, the split channels were Marshall

ís first hi-tech amps. The split channels are a little harder to find used

than the master volumes, but you should be able to find one. It sounds quite

like its brother, the master volume, but with some (limited) channel

switching capabilities.

General JCM 800 info:

Introduced in 1981 (split channel amps in 1982) and discontinued in 1989.

Superleads are available as heads only, 50W split channel and master volume

amps available as heads, 1x12" and 2x12" combos, while 100W split channel

and master volume amps were available as heads and 1x12" combos. Pre-1984

JCM 800s for the American market were shipped with 6550 power tubes and

sounds a lot different from the EL34-equipped "standard" ones. Converting an

originally 6550-equipped amp to accept EL34s is a minor mod and should cost

you more than £30. The 2203 was reissued in 1995 as a special limited

edition amp in red tolex, with matching 4x12" cabs.


25/50 silver jubilee series:

Also a split channel amp, introduced in 1987 to celebrate 25 years of

Marshall amps and Jim Marshallís 50 years in the music business. The front

panel layout is simpler than the JCM 800 split channelsí with only one gain

knob, one "lead master" and one "output master". The gain and the "output

master" knobs are push-pull and activates "rhythm clip" and lead channel

respectively. The amps were made in silver/grey tolex and also feature a

half/full power switch (pentode/triode) and an FX loop, but no reverb.

Generally considered to be one of the best sounding (Yes, I know that "best"

is a relative term...) Marshalls ever, it's a little brighter sounding than

the "ooouumphy" JCM 800s, but not as bright as a JCM 900. These amps will

give you a sound that'll suit almost anywhere in the rock spectrum of music,

from Jimi Hendrix and Led Zeppelin to Metallica. The jubilee amps have

recently become something of a collector's item and finding one could

require some serious research. The 2555 was reissued in 1996 as the JCM

Slash signature amp, with vintage 30s-equipped 4x12" cabs.


JCM 900 master volumes:

The JCM 900 master volume was designed to give the late 80s metal bands what

they wanted the most, MORE GAIN. And more gain they got. However, the sound

of the 900s is not as ballsy as the 800sí. To get the extra gain, the diode

clipping-circuit was modified which in turn gave not only more gain but also

a somewhat buzzier and brighter distortion. But the players loved it anyway,

and lots of people still do. By backing the gain off, you decrease the

amount of solid state-clipped signal (the clipping circuit is fed with less

signal the lower the gain is set) and you can get some killer, more vintage

"true tubeish" tones out of these amps. The tones produced by these amps

will first and foremost suit modern thrash metal, hardcore or punk players

who donít need a clean sound. In 1994 the Mk III was replaced by the Mk

IIII, also known as the SLX. These amps feature an extra ECC83 (12AX7)

preamp tube and even more gain than the original JCM 900 master volumes.

JCM900 dual reverbs:

Featuring a clean channel with some real headroom, sounding a lot less

"Marshall" than previous "clean" Marshall-made channels. The overdrive

channel is less buzzy than the JCM 900 master volume and does not have as

much gain. Front panel functions include individual gain controls for each

channel, a shared 4-band EQ, and individual reverb and master volume

controls. Without knowing it, Marshall made an amp that suited the next

generation of "alternative" bands. When the gain is set low on the overdrive

channel it'll sound somewhat "retro" and turning it up a bit (not past 2

with humbuckers, preferably in neck position) results in a chunky ballsy

tone. Scooping out the mids and turning everything else up will give you an

"almost-SLX" sound, that can be used for more "metal" applications.


General JCM 900 info:

The JCM 900s were originally equipped with EL34 power tubes, but from 1994

onwards they came with 5881 power tubes due to the fact that, at that time,

EL34s were becoming hard to find. The die-hard Marshall user's consider this

a cop out, while others (including me) think that putting 5881s into the

900s were a not-so-bad move since 5881s made the 900s sound less brittle and

a little more ballsy. Anyway, itís no big deal modding a 5881-equipped amp

to accept EL34 tubes. The master volumes' came as 50W heads and 1x12" and

2x12" combos and 100W heads and 1x12" combos. The dual reverbs came as

heads, 1x12" and 2x12" combos in both 100W and 50W models. No SLX combos

were ever made.


Anniversary series:

The most versatile Marshall to date. Three completely individual channels,

clean, crunch and lead. Clean is clean, jazzy clean or country clean or pop

clean, you decide. Crunch features three gain modes (A, B and C), A gives

you classic superlead crunch, B takes you into 2203 territory and C gives

you the SLX scream, and a little more. The lead channel continues where the

crunch channel stops. Insane amounts of gain, I havenít heard more gain

coming from an amp, with a possible exception for the JCM 2000. Whatever

your preferences might be, the anniversary series amps has got the sound for

you. The design is also very hi-tech. Channel switching is

MIDI-controllable, the FX loop has individual levels for each channel and is

switchable from serial to parallel, the power amp features two different

damping modes (low and high) and an "auto" option that automatically assigns

the "right" mode for each channel, a recording compensated balanced XLR

output, a low/high switch for pickup compensation and a "low volume

compensation" that fattens the tone up a bit at low volumes. The anniversary

series amps were introduced in 1992 and the first year the amps were made in

blue tolex. Special (brass-plated chassis, gold logotype) limited edition

series amps were also made in 1992. The series were continued unmodified,

but in black tolex, until late 1994 when the lead channel was re-designed

and the amps renamed with an "LM" after the model number. The LM amps are

all fitted with 5881 power tubes as opposed to the EL34s that the originals

came with.