Hands-On Review:Marshall JVM Guitar Amplifiers
A new top-of-the-line Marshall loaded with kick-assitude
By Jeff Kramer
The real “heart of rock-and-roll” has to be the Marshall all-tube super-lead amp. From the Hendrix era down to today’s current crop of guitar-wielding Wylde men, Marshall amps have provided the power and tone needed to rage onstage.
The JCM, JTM, TSL, DSL, and Vintage Modern are the Marshalls that have ruled the rock stage and established this long and proud Marshall tradition. With so many great amps setting the standard, coming up with a new flagship amp had to be a challenge. Marshall has risen to the task—admirably. The new JVM410H 100-watt head fills big boots. It is an extraordinary amp—everything you love about an all-valve, high-gain Marshall and more. It has more gain than any Marshall ever, more channels, more switching, more versatility. It is quieter, stronger, and amazingly easy to drive. In short, it lives up to its promise on all counts.
Classic and classy
The look is standard Marshall trad: black case, gold panel, and big white Marshall logo to provide rock cred. You can’t mistake it for some poser amp. The most obvious difference between the JVM and other Marshall amps is the front panel. It’s filled with knobs—a control freak’s delight. There are 28 to be precise plus eight switches.
So many controls might make you assume that it’s complicated, but it’s not. It has four independent channels, and most of its knobs are Marshall’s standard channel set (gain, bass, mid, treble, and volume) repeated four times. There are also individual channel reverb level controls. In the master section, there are two gains that you can switch between. The last two knobs are global resonance (it’s the first Marshall amp to have a resonance knob rather than just a switch) and presence. Once you understand the layout, it seems simple and straightforward in spite of the number of knobs.
In addition to the four sets of panel controls, each channel has a three-way mode switch that changes the preamp gain structure, adding gain stages as you move from green to orange to red. This, in effect, makes the JVM410H a 12-channel amp. It’s the number of channels you find in modeling amps, but these aren’t modeled versions of anything. All 12 are pure, real Marshall tube. You have the basic clean, crunch, and overdrives that have shaped rock music over decades. And the modes add three variations of each. With all of this to work with, the JVM can match the tone of any Marshall of yore and come up with new tones that take high gain to new highs.
Firing it up
I tried out the JVM410H atop a 4x12 Celestion Vintage 30 cab and started pumping out riffs in the clean channel. One thing that impressed me immediately was how quiet the JVM’s clean channel is. It’s almost as if it’s off until you make sound on your guitar. And when it is making sound, the clean channel is incredible—glassy and pure. Switching from green to orange to red modes bumps up the gain in increments, so that in red you have a sweet bluesy tone that is great for leads and responds nicely to the tone knobs, allowing you to focus the distortion at a desired frequency.
The crunch channel has the standard preamp topology of gain first, tone second; so in green mode it’s like the legendary Plexi but with a bit more gain. Switching to orange mode makes it tonally similar to a JCM800. Switching to red ups the gain more, so that the amp performs like an 800 on steroids.
With the overdrive channels, the gain starts high and goes insane. OD1 and OD2 are similar, both clearly in the metal and hard rock zone. The difference is even more gain in OD2 and a lower frequency center, dropped from Marshall’s standard (around 650Hz to around 400Hz). The effect is more power and more punch for leads that slice and rhythms that grind and churn. Cool.
The JVM comes with a six-button footswitch that is itself a marvel. First, it’s programmable. In switch assign mode you determine which button switches what. A lot of things on the JVM are switchable: Master Volume 1, Master Volume 2, channel and mode, reverb on/off. Even one of the amp’s two FX loops, the series/parallel circuit, can be switched. In its preset memory mode, the footswitch accesses JVM’s memory. In this mode, you can lock in a full setup, assign it to a footswitch, and save it. When you tap the footswitch it recalls all the settings—channel, mode, and effects. You can even use a channel multiple times with different settings.
The footswitch has another really cool feature. It connects to the amp with a regular guitar cable. No multiwire, hex-headed special cable to hang you up bad if it goes south during a gig or you forget to pack it. With this footswitch, you just plug in a spare guitar cable. If you need a longer cable on a big stage, you can sub a longer guitar cable.
Other pro features
In addition to its six-button footswitch, the JVM can be controlled from a MIDI footcontroller to make it even more facile onstage. If you’re running a MIDI effects unit, for example, you can set up MIDI commands that change the channel and effects unit in tandem, thus reducing the amount of tap dancing required to get you there.
Vintage purists will bemoan the use of digital rather than spring reverb, but there are bad digital reverbs and good ones, and this is a good one—very natural, smooth, and easy to precisely adjust. And of course, it won’t freak out when the floor starts bouncing. Separate level controls for each channel and on/off footswitching make it easy to use onstage, and it has natural decay when you switch to another channel or turn the reverb off.
JVMs provide an emulated line out for recording or feeding a board. Both the JVM410H head and the JVM410C 2x12" 100-watt combo have speaker outs for all relevant impedances, and the JVM410C combo is equipped with two different Celestian Marshall/Celestion 12" models (one Vintage, one Heritage) to make the sound richer.
With its pro features, tour-tough build, extensive switching, four channels with modes that give it vast tonal range, and insanely high gain, the JVM410 is a worthy flagship to carry the Marshall standard. It is classic Marshall with modern refinements. The Marshall roar is alive and kickin’, and rockin’ louder than ever.
Features & Specs
- 100-watt all-valve
- Valve complement: 5 x ECC83 (12AX7s) in preamp, 4 x EL34s in power amp
- 4 independent, footswitchable channels – Clean, Crunch, OD1, and OD2
- Each channel boasts 3 footswitchable modes – Green, Orange, and Red
- Studio-quality, footswitchable digital reverb with level controls for all 4 channels
- 2 footswitchable Master Volumes
- Internal amp memory remembers most recent switch selection for all 12 modes
- 2 FX loops: series/parallel and parallel
- Series/parallel FX loop is footswitchable
- Emulated line out
- 6-way, 7-LED footswitch that’s programmable
- Footswitch connects with standard guitar cable
- All switching can be done via MIDI
- Made in England
- JVM4410C combo features 2 Celestion 12" speakers