Marshall Amplification BOOK-00079-00 User Manual
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ENGLISH
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ENGLISH
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“
Marshalls were
the only amps that
could follow Jimi into
the musical realms he
chose to play in and
come out the other
side delivering the
goods, 100%
”
James 'Tappy' Wright
“
Anybody
wanting quotes
from Jimi regarding
his Marshall Amps
will find hundreds
recorded on his
albums and
videos.
”
Neville Chester
Components: Wherever and whenever possible, we have gone back to
the original manufacturers for all components to ensure maximum
authenticity.
Valve compliment: Three ECC83s in the pre-amp and a quartet of
KT66* valves in the power amp working in push-pull. All valves are of the
highest quality available and are subjected to our stringent grading and
testing processes.
*KT66: these output valves were standard issue in mid-sixties Marshall
Amplifiers and yield a fat, round tone that has a distinctly vintage flavour.
The way the pre-amp’s three ECC83s (labelled V1, V2 & V3 in the
photograph) are utilised is as follows -
V1 is the first pre-amp gain stage for the High Treble and Normal
channels. Each half of the valve (the ECC83 is a dual-triode 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 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 (providing a high input impedance and
a low output impedance for the signal to drive the pre-amp’s passive
tone network).
V3 is the amplifier’s phase inverter and sits at the very end of the pre-
amp section. V3 divides the single ended input signal into two separate
output signals that are inverted with respect to each other - hence the
name ‘phase inverter’ (a.k.a. ‘phase splitter’). The two resulting signals
are then fed to the push-pull power output stage of the amplifier.
Tone Circuit: In typical Marshall fashion, the Super 100JH’s shared tone
network is both passive and interactive. By interactive we simply mean
that the settings of the Bass and Treble controls affect the amount of
mid-cut available via the Middle control.
Tag Boards: The tag boards used in your handwired Super 100JH are
exactly the same as those in the original in terms of thickness and matrix
pitch. The material we’re using is made exclusively for us and is
registered with UL as ‘Marshall EM42 brown.’ The reason we didn’t use
a board with the exact same chemical composition as in the original units
is simple - that material doesn’t pass current safety legislations
concerning flammability!
Transformers: The mains (power) and output transformers are vital to
the performance, sound and feel of an all-valve Marshall amplifier. In
order to achieve authentic tone and performance, we went to Drake for
these important components as they are the company that supplied us
with the transformers used in the original Super 100. Fortunately, Drake
still had all of their original documentation intact in their files.
Mains (Power) Transformer: The Mains Transformer in this re-issue is
an exact duplicate of the original in terms of electrical performance and
behaviour. This said, some constructional alterations had to be made in
order to pass current Safety Legislations. These alterations have no
impact on tone or performance whatsoever!
Output Transformers: The Output Transformer in your Super
100JH is identical in every single aspect to the original ones used
back in 1966. The inclusion of the fully functional 100V Line tap,
while being historically correct, is of little or no use on this
particular model, if truth be told! The reason it was present in the
60s was because the same transformer was also used in the
100-watt Super PA heads (model 1968) as well - enabling the
head to drive multiple remote 100V line speakers in various
locations within a particular venue.
Power supply: This circuit has the same filtering on the H.T.
(high voltage DC, a.k.a. the B+ voltage) line as the original
versions, a factor that contributes to the Super 100JH having a
unique, dynamic characteristic all of its own. The power supply on
the Hendrix head is notably different to that of the post '68 Plexis
and, when the amp is fully cranked, has a very different regulation
(i.e. its ability to supply what is demanded from it). This coupled
with the period correct smoothing capacitor values produces that
characteristic ‘sag’ (compression).
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 it lifelong resistance to corrosion. This is a
deviation from an original 1966 Super 100 head as it had an
aluminium chassis. The reason we have made this change is for
strength, longevity and reliability reasons, and we can assure you
that it has no tonal effect whatsoever. Aluminium is a very soft
metal and the one thing that all chassis from this period have in
common, is they are easily distorted, buckled, bent or even
cracked - due to the material's inherent weakness. A lot of this
can obviously be attributed to the sheer size and weight of the
transformers. The steel chassis used in your Super
100JH doesn’t suffer from such problems and is
much more practical and roadworthy.
Front Panel: Extra thick, gold coloured Plexiglas
(actually Perspex, causing some people to refer to it
as ‘Perplexi’!), exactly the same as the original. And,
just like the original, the front panel is that of a
JTM45 (hence its ‘JTM45’ nomenclature) - used on
the first Super 100s as standard. Specific details
pertaining to the front panel features can be found on
the next page of this manual.
Rear Panel: Made from cream styrene with gold
print, just like the original reference units. Specific
details pertaining to the rear panel features can be
found on the next page of this manual.
Head Cabinet Construction: High-grade, flawless
(knot-free) Baltic birch-ply with finger-locked (a.k.a.
‘comb’) joints for maximum strength. The main
cabinet frame (sides, top and bottom) is 15mm ply;
the front baffle is constructed from 12mm ply, while
the back of the cabinet is 9mm ply. All edges have a
15mm radius.
Head Cabinet Cosmetics: The small gold Marshall
script logo, black Levant covering, original venting,
beading and piping all duplicate the look and style of
the originals.
V1
V2
ECC83 VALVES
KT66 POWER VALVES
V3
Photo credit - Ulrich Hand / © Authentic Hendrix, LLC - Big Apple Club, Munich, West Germany - 9th November 1966