Marshall MF350

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, Marshall's R&D team set about designing such a product. The outcome of their labor is the Mode Four MF350, a 350 Watt head, and four Celestion-loaded, 4x12" cabinets that are actually larger in size than the regular Marshall 1960 4x12" cabinets (the industry standard). In addition to delivering aggressive, bottom heavy, modern, high-gain sounds, Marshall also wanted the Mode Four to offer great clean tones as well as the myriad of overdriven sounds that have made Marshall famous. To achieve such tonal flexibility, the MF350 boasts a "two amplifiers in one" design. These two amps, named AMP 1 and AMP 2, both feature two footswitchable modes. This gives the player four mode options – hence the head's name. 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. Footswitch included.



Fully Loaded For Professional Use

From the very start, the Mode Four was created with the professional guitarist in mind. To this end it boasts a host of carefully thought out features that have been designed to give you, the player, the ultimate in professional flexibility and control.



These include:

Mode Four – a History & Overview

Since Marshall'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 Marshall amplifier, the JTM45, was built in 1962 as a direct result of my listening to the requests of the guitarists who frequented my music shop at that time. Forty years later, Marshall is still listening to the thoughts and wishes of guitarists of all playing styles and from all walks of life." 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.

Looks that Kill!

To compliment the hard-hitting sonic goals, the MODE FOUR sports a new look that is as aggressive and as bold as the amp sounds, while remaining true to Marshall's distinctive and instantly recognizable aesthetics.

"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 consulted with a large number of players. The most popular layout in terms of both looks and user friendliness places the head's Master Section in the middle of the front panel. 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.

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 Marshall clipping characteristics. The valve operating points (bias) of AMP 2's pre-amp are radically altered to produce super saturation and overdrive – more, in fact, than in any of Marshall's valve amps to date. 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 Marshall designs. To this end, the resulting clean sounds ring with the bell-like harmonics that only a valve driven pre-amp can normally deliver. When an overdriven sound is selected the resulting valve break-up is never harsh or unnatural sounding. 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. Marshall has gone to great lengths to ensure that each valve delivers its maximum sonic benefits at all settings and volume levels. The true extent of the dynamics that the ECC83s impart become apparent when you turn the volume control on your guitar up or down – the MF350 reacts and behaves exactly like an all-valve amp.

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, Marshall's proprietary Dynamic Clip Level technology emulates the compression effects introduced by the interaction between a valve output stage and its power supply. 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.

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. Marshall's engineers found that at the onset of power amplifier clipping, the already low damping characteristic is reduced still further. This results in uncontrolled movement of the speaker cone (i.e. the power amplifier starts to "woof" out and notes become indiscernible). 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.

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 Marshall's critically acclaimed speaker emulation circuitry.

Masterful Features

In addition to housing the expected Master Volume control, the MODE FOUR's Master Section also has the following beneficial features:

Size Does Matter!

To ensure optimum performance of the Mode Four, four complimentary 4x12 in. 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. 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.Marshall's also investigated the effect of the relative positioning of the speakers within a cabinet and found that by moving them around they were able to fine tune the mids and, to a lesser degree, the lows, for optimum performance. Marshall also increased the thickness of the cabinet's plywood back to control vibrations created by the high-pressure levels inside the cabinet. The Celestion speaker that came closest to the desired full-stack tone was the renowned "Vintage30". By working closely with Celestion, as Marshall has for the past four decades, the engineers used this speaker as a starting point and developed the Vintage30MF, a 12 in., 70 Watt speaker that delivers a full, punchy "in your face sound." This exclusive speaker is fitted into the 280 Watt, 16 Ohm MF280A (angled) and MF280B (straight) cabinets. Market research has shown a growing number of guitarists only use a single cabinet, half stack set-up. To cater to them Marshall also designed a pair of 400 Watt, 8 Ohm cabinets – the MF400A (angled) and MF400B (straight) – that can handle the 350 Watts which the Mode Four delivers at 8 Ohms. The perfect speaker for both was found to be the Celestion G12K-100, a 12 in. speakers that produces a rich, well-balanced tone.

Specifications