Marshall JVM 410h

PolarityMan

I've had this amp through 2 bands and about 8 years and have used it exclusively live and in the studio throughout that time.

First the specs, this is still in the Marshall product roster and is a 4 channel, 100 watt valve head. Each channel has 3 gain modes, green, orange and red to give you effectively 12 different gain configurations. In addition to this the amp sports individual EQ for each of the 4 channels, 2 switchable master volumes, a switchable parallel fx loop, a switchable reverb and a non-switchable serial loop between the power and preamp stages. Best of all these options are all controllable via midi making this amp remarkably flexible. 

The Good

So to start with, the good. The amps flexibility is undoubtedly it's strongest point, the midi programability makes it pair extremely well with a multi-fx pedal which is how I use it (with a boss-GT10). Patches are easy to program, you simply setup the amp channel how you want it and then double tap the midi button on the front, the next patch change you make on the multi-fx will then become associated with the amp setting. I use this extensively having my fx on the boss-GT10 switch at the same time as the amp channels via one stomp.

You can use the muti-fx in a number of configurations and I have been through using 4CM in both the loops as well as using the unit just in front of the amp. The programmable loop even when set to 100% wet has a tiny amount of dry signal bleed, which made it awkward to use with the few patches where I run amp modelling (to get fenderish cleans) so I found 4CM worked best in the insert loop.

Since each channel has it's own volume I generally run the patches on the muti-fx at unity and use the per-channel volumes to balance the individual channels and the switchable master volume to provide solo boost. This makes setting up at gigs, quick, predicatbale and no fuss, I simply adjust the master volumes an presence per venue and tweak the distorted versus clean balance as required.

The Average

So I've spent a lot of time talking about switching and work flow and haven't mentioned the sounds yet. The sounds are serviceable but even with 12 different gain levels there is definitely a similar character to the distorted channels. I tend to care most about pure cleans with no breakup which I get out of clean orange (because clean green bypasses the per channel volume control and uses gain to control volume). I have in the past used the crunch channel as my main distortion channel boosted by a tubescreamer model but recently I've been rocking OD1 and OD2, which although a little noiser gives me more aggressive rhythm tones.

The sounds in here are all distinctly marshally and perfectly adequate, you can hear them on our EP and album but I would say they aren't top of class tones from a metal perspective.

PolarityMan

The Bad

There are a couple of niggles that are important to note with this amp, although I understand that the Satriani signature version of this head has solved them. 

The first is the channel switching gap. There was a long thread on this on music radar but the long and short of it is that by design this amp has a circuit which mutes the output while changing channels for 50ms in order to prevent a "pop". In my experiments I actually measured this at more like 75ms and there was still a slight pop on channel change, particularly from clean to the high gain channels. 

Many others who owned this amp couldn't hear this gap but I actually measured it by recording it and analysing the waveform an posted in the JVM forum and wrote to marshall where both marshall and the amp designer on the JVM forum confirmed that it is part of the design.

This bugged me for a really long time as we have a lot of songs where we kick in the distortion to create a dramatic effect from clean and it was sounding like a flam with the drums but actually over time i have just learned to switch fractionally early so the silence happen before the first distorted note.

The other niggle is that the amp is quite noisy, there is a pretty absud amount of gain available but the OD1 and 2 channels can have quite a bit of hiss and squeal on higher gain modes. I used the noise gates in the GT-10 and before that an ISP decimator to tame these. The decimator wasn't an ideal solution since it would kill delay trails on my clean notes but with the GT-10 I can automatically disable the gates for clean patches so the noise thing is a total non-issue for me now.

All in all if I was re-buying I'm not sure I would go for this amp again, there's nothing wrong with it as such and it'd perfectly serviceable but I think that now there are some better contenders on the market at a similar price point like perhaps the EVH 5150 iii that probably have the edge with modern distortion tones.

ICBM

The difference between this version and the Satriani one is massive. The only downside of the JS is that you lose the reverb in order to gain the noise suppressor, but the reverb isn't that great anyway as I'm sure you've found - if you're a reverb user you probably want a dedicated reverb unit. (A friend of mine who owns one is, and puts the reverb pedal in the pre/power amp insert loop rather than the FX loop itself, so it's separate from the FX loop switching.)

Allegedly, Marshall wanted Satriani to endorse the original JM410 and sent him one, but he didn't like it for those reasons until his tech extensively modified it and sent it back to be re-done properly… which doesn't say a lot for Marshall's R&D department if they needed someone else to tell them how to do it right! The JS also has a choke in the power supply - the standard one has a (cheaper) resistor - and sounds richer and more dynamic as a result.

PolarityMan

The reverb is ok, not very flexible compared to the one in my gt10 but if your not doing big washes it can be useful, think more for clean lead tones than for post rock lushness. Tbh I'd rather use an external noise suppressor with greater control than lose the reverb, especially as using 4 cm you can use 2 subtle ones, one in the loop and one out front rather than one more savage gate. The channel switching is really my main beef with this amp.

Drew_TNBD

I really loved my JVMJS until it broke, and I had to send it in to get fixed. When it came back, it sounded more vintage modern-y and less out and out metal.