MODE FOUR – a History & Overview
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ince the company’s dramatic emergence
in 1962 with the now legendary JTM45 head, and thanks
to groundbreaking products such as the 100 Watt Plexi head as well as the JCM800, JCM900 and JCM2000 Series,
players and press alike have considered Marshall to be the world’s foremost
designer and manufacturer of valve (tube) guitar amplifiers. Marshall’s
reputation as an industry leader is not limited to all-valve amps and 4x12”
cabinets (Jim Marshall is responsible for the birth of the 4x12” cab, the
angled 4x12” and the iconic stack) either – thanks to cutting-edge products
such as Valvestate in the ‘90s and AVT (Advanced Valvestate Technology) and
MGIII in the 2000s, the company continues to define the very pinnacle of hybrid
and solid-state guitar amplification.
Jim Marshall has always maintained that one of the major reasons his company is consistently on the cutting
edge is its willingness to pay attention to what end users want and react accordingly. As Jim himself so aptly
puts it, “The very first
As
a direct result of Jim’s simple but effective “listen to what our customers
want” philosophy, comes the company’s latest technical and tonal
breakthrough – the MODE FOUR.
The Sonic Goal
In modern rock guitar, there has been a dramatic increase in
the demand for
an amplifier with the following attributes – incredible high gain, dramatically
expanded headroom and a low-end response
capable of comfortably accommodating detuned 6-string,
7-string and baritone guitars. With these
requirements in mind,
Looks that Kill!
To compliment the aforementioned sonic goals, the MODE FOUR
sports a new look that is as aggressive and as bold as the amp sounds, while
remaining true to
Two Amps in One
In addition to delivering aggressive,
bottom heavy, modern, high-gain sounds, Marshall Marshall
To be precise: AMP 1 is the “classic” amp
and its two modes are CLEAN and CRUNCH, while AMP 2 is the high-gain, “modern”
amp with OD1 and OD2 as its two modes. AMP 1 and AMP 2 each have their own
totally independent, valve pre-amp section and
the MODE FOUR’s proprietary power stage automatically reconfigures itself
depending
on whether AMP 1 or AMP 2 has been selected. More details on this are presented
later.
“Guitarist Friendly” Front Panel Layout
An important design criterion was to ensure
that the amp is as guitarist friendly as possible. To ensure this, Marshall
Because the MODE FOUR’s two amp sections,
AMP 1 and AMP 2, are separated by the Master Section it removes the “which channel does this control work on?” confusion often caused by multi-channel amplifiers due to the close
proximity of their front panel controls.
MF350 – State of the Art Design
Integration.
The
MF350 is a result of pragmatic design choices utilizing state-of-the-art valve, solid-state and digital technologies.
1. Separate Valve Pre-amplifiers.
In order to achieve the wide tonal
variations of AMP 1 and AMP 2, the
gain, clipping and frequency characteristics of the triode valve stages in each pre-amp are
very different. The fundamental differences in the tonal
requirements for AMP 1 and AMP 2 dictated the need for two entirely independent
valve pre-amplifiers. AMP 1 is voiced so it
can produce great clean and overdrive tones. The two stages of its ECC83 (an
ECC83, a.k.a. A12AX7, is a “dual triode,” meaning it contains two triode valve
stages) have been biased to produce classic
Bias, gain and frequency response are
all controlling factors that govern the dynamic response of valve
pre-amplifiers. AMP 1 is biased at a
relative mid point and its medium gain and open frequency response, post
clipping, yield the dynamic response typical of all classic
In contrast,
the valve sections of AMP 2 are biased close to cut-off, yielding a more
compressed tone. Also, high-frequency
roll-off is tailored to add a modern, aggressive edge, especially when compared
to AMP 1’s more organic tone. Even when the ECC83 in AMP 2 is saturated to its
very limit it still provides musical harmonic overtones, dynamics and that
all-important, guitar playing commodity, feel.
2. MODE FOUR Power Amp Delivery –Tone, Punch and Feel
The MODE FOUR’s unique, fan cooled
power stage recreates the warm, musical feel and three-dimensional
sound of an all-valve power amp. It features a
fully balanced, differential mode, current feedback power amp that can deliver
a staggering 350 Watts into 8 Ohms and accurately emulates the damping
characteristics (the essential interaction between the power amplifier and
loudspeaker – a relationship that is frequency dependant and is therefore often
referred to as Frequency Dependant Damping (FDD)) of an all-valve design.
Adding to the overall dynamics and punch of the output stage,
As mentioned
earlier, the MODE FOUR’s power amp reconfigures itself dependant on whether AMP
1 or AMP 2 has been selected. Damping characteristics play an absolutely vital
role in the sound and feel of a valve output stage. When AMP 1 is selected, the MODE FOUR’S power
amplifier is reconfigured to reproduce the damping characteristics of the
power-amp of a Marshall 100 Watt Plexi or 2203.
When switching to AMP 2 the damping is significantly reduced relative to
when AMP 1 is selected. This has the effect that the impedance characteristics
of the loudspeaker, which are dependant on frequency, have a dominant influence
on the power amplifier response. This
produces an under-damped response, resulting in an emphasized, resonant low end
and accentuated treble. This said, even though AMP 2’s power amp configuration
is relatively loose when compared to AMP 1’s, the dynamic response is still
tight. The graph below
shows the difference in frequency response between the two: AMP 1 is
green, AMP 2 is red.
350 Watt RMS Output
Early technical research ruled out many
options for achieving the all-important, extended low-end response required of
the MODE FOUR. What became apparent from the start was that the unusually low
damping characteristics needed to give the required sound and feel had its own
particular drawbacks.
With this information at hand, R&D
looked at various options to combat this limiting factor. The MODE FOUR’s
unique power amplifier topology allows for extremely high headroom (i.e. power
to be delivered before clipping) in conjunction with a low damping
characteristic. This enables the MODE FOUR to deliver the increased bass
resonance associated with low damping, without the drawbacks of other designs.
Added Tonal Flexibility and Muscle
In
addition to having their independent tone controls for Bass, Middle and Treble,
AMP 1 and AMP 2 each boast a SCOOP button. When engaged, these buttons
literally “scoop out” the mids, resulting in a modern, aggressive sound.
In addition, AMP 1’s Scoop button also accentuates the highs while attenuating
the lows. AMP 2’s Scoop affects only the mid range.
To add further to its
tonal flexibility, AMP 2 also features a three-way TONE MATRIX control which
reconfigures the tone network for three different middle frequency settings. This is different than parametric equalization
because the Treble and Bass controls remain completely interactive with the
Middle control. Each of the three positions produce
vastly different distortion tones.
Position
1 – has
the highest frequency of ‘mid dip’ and yields a classic Marshall tone with the ‘woody knock’ in the mid frequencies normally
associated with high gain
Position 2 – lowers the mid frequency and tightens
the low middle frequencies, resulting in a heavier sound with less ‘woodiness’.
Position 3 –selects the lowest middle frequency and is the most extreme of the three. Here the low middle frequencies are completely removed leaving an exaggerated bottom-end that is thumping but still tight.
The
graph below illustrates the difference between
the three settings of AMP 2’s TONE MATRIX control.
Digital
Reverb, Parallel / Series FX loop and Emulated D.I.
The MODE FOUR features a footswitchable
digital reverb that is custom-voiced to be entirely natural sounding, and its sonic quality is comparable to a
high-end effects processor. For
additional flexibility, AMP 1 and AMP 2 have
independent Reverb Levels Controls. The amp also boasts a Parallel/Series
Effects Loop, with each pre-amp having its own FX Mix control. When either of
these FX Mix controls is turned up full,
the loop converts to Series operation. The rear panel also houses two Emulated
DI Outputs – one XLR and the other a ¼” jack – and both benefit
from
Masterful
Features
In addition to housing the expected
Master Volume control, the MODE FOUR’s Master
Section also has the following beneficial features:
RESONANCE
Control: by decreasing low frequency damping in the power amp this control
affects the low-end rumble, overall tightness and fullness of the sound.
PRESENCE
Control: by decreasing high frequency damping in the power amp this control
adds high frequencies to the tone, creating edge and bite.
TUNER MUTE
Switch: Engaging the Tuner Mute Switch mutes the speaker outputs and D.I’s of
the MODE FOUR, but allows the signal to pass to the Tuner Out jack on the rear panel. As well as facilitating “silent tuning,” this switch
is ideal for guitar changes.
SOLO LEVEL
Control: this makes a universal, footswitchable “Solo Boost” possible. When set
at maximum, a volume increase of 6dB (i.e.
twice the volume) occurs.
Size Does Matter!
To ensure optimum performance of the
MODE FOUR, four complimentary 4x12” cabinets were designed – two angled and two
straight. The first thing that strikes you about these cabinets is that they’re
a good three inches taller than Marshall’s regular 4x12”s. Even though this
makes a MODE FOUR stack incredibly impressive and imposing, it wasn’t done for
aesthetics – it was done for tonal reasons. By making the cabinets bigger, the
resonant frequency of each one is lowered. When combined specially designed
Celestion speakers, this enhances and compliments the extra bottom-end
capabilities of the MODE FOUR head.
The Celestion speaker that came closest
to the desired full-stack tone was the
renowned “Vintage30”. By working closely
with Celestion, as
Market research has shown a growing
number of guitarists only use a single
cabinet, half stack set-up. To cater to them
The Line-Up
The following MODE FOUR units will be
launched at Winter NAMM, January 2003:
MODE FOUR head:350 Watt, hybrid amplifier with 2
independent pre-amp
sections and 4
footswitchable modes; footswitchable Digital Reverb with dual controls;
footswitchable universal “Solo Boost;” Parallel FX loop, ¼” and XLR Emulated
Outputs; and a Tuner Output with Mute switch. A sturdy, 6-way LED footswitch
enables instant switching between the MF350’s 4 modes plus Digital Reverb
on/off and Solo Boost on/off is also included.
MF280A Cabinet: 280
Watt, 16 Ohm, mono, angled-front 4x12” cabinet loaded with four, custom-voiced
70 Watt 12” Celestion/Marshall “Vintage 30MF” speakers.
MF280B Cabinet: as
MF280A but with straight front.
MF400A Cabinet: 400
Watt, 8 Ohm, mono, angled-front, 4x12” cabinet loaded
with four custom-voiced 100 Watt, 12” Celestion/Marshall speakers.
MF400B Cabinet:
as MF400A but with straight front.