Price paid: A$ 1100
Purchased from: Ebay
Features: The Marshall JCM 900 4100 is a 100watt valve head featuring 2 channels (Simply named A & B), with a single 4 band equalizer, individual volume, gain and reverb controls. Has a single guitar input, a footswitch input, 2 loudspeaker outputs (Switchable between 8, 16 and 4 ohms (4 ohms in stereo)) a line out and effects loop, my amp was built in 1995.
This amp uses 3 ECC83 (12AX7) preamp valves and 4 5881 (6L6) power valves valves, but can be switched to KT77's or hot grades of EL34, or average EL34s with slight modification. I play mostly thrash metal, and a bit of NWOBHM, and I love this amp to death, I found it on ebay whilst just browsing for a good deal (Was going to head off to Melbourne and buy a Bugera, but wanted to see if I could get something better). The tone from this amp is very versatile, and I could get just about any genre from it (except death metal), I find it to have a bit of an early Megadeth kind of tone when used with my guitar and cab (Cort VX-2V and Marshall 1965A cab).
As you should know, this isn't an amp for low volumes, no valve Marshalls are, and not many valve amps in general are. But on 50watts (It has a wattage Switch, between 50watts and 100watts (50watts and 25watts on 50watt models)) at around 1 1/2 I can still get a nice overdriven metal tone without killing my ears. This amp could quite easily do a gig, and even a smallish one unmic'd, it's f--king loud.
The EQ is responsive, but not as much as some high gain amps, but with ease you can find a nice setting for brutal overdrive/distortion, and great cleans. I do feel maybe another channel could be added with slightly different overdrive, for a little variety (That kinda crunchy tone you hear in some songs). One thing I have come across that annoys me is that in order to change the bias, you have to completely take this amp out, and access the main board, which requires confidence, experience, and a plastic screwdriver/rubber gloves or something, so you don't fry yourself with the 400volts+ plate voltage surging through this thing. Marshall should've just put a test point at the back of the amp with an easily accessible trimpot. // 9
Sound: I'm using a Cort VX-2V with EMG-HZ H4's running straight into the amp, with this, I can get an early Megadeth style overdrive (Peace Sells - Rust in Peace), a nice British overdrive, bluesy cleans, and any other old school tones, quite a versatile amp, although I do have a little bit of flatness in my tone which sometimes I can't throw off, but I feel this could be dismissed with better tubes (Currently have Sovtek power valves, and National preamp valves installed)
I was surprised by just how quiet this thing was, considering I'm using an average guitar, with a shitty cable and a shitty cab in a small house, there's your little bit of background hum, but apart from that, quiet as. When on 50watts, I've been able to crank channel A (The clean(er) channel) to 10 without it distorting (With the gain on 2) which I was quite impressed with, but if the amp has been turned on for a while, and channel B is cranked up loud, you'll get a bit of distortion.
But basically, the tone this amp gives off is great for thrash, NWOBHM, general oldschool metal, hard rock, blues and anything around those. // 9
Reliability & Durability: Well, seeing as this is a Marshall, I believe it will last me for yonks, I've only had it for about a week so far, but it's already 13 years old (was made in 1995), and it's in perfect condition, aside from slight warping on the front plate (From extreme heat). I would definitely use this amp without a backup at a gig, especially seeing as it has some failsafe circuit, which'll apparently keep it going in the event of a valve failure (read it in the manual, never put it to the test though)
All the knobs feel like they're sturdy, and wouldn't break, the handle is very strongly in place, and can support the things entire weight (Quite a lot, so don't go carting it around all the time), the only thing I'd watch out for is scratching the vinyl. // 10
Impression: For my styles of music, this amp has provided a perfect match, and if I ever needed to boost it slightly, an overdrive pedal on very low settings would do the job just to push the valves a little further. Compared to the other amps I've used (Old valvestates, and an experimental rig), this is brilliant, what I've always wanted from an amp. If this was stolen or lost, I would either buy a new one, or look into a JVM410H (Just because it has more channels and separate EQ's), although I would definitely stick with Marshall. I haven't really had much of an opportunity to compare this amp with over valve amps, but if there are many out there better than this, then wow. They must be good.
This amp is a full valve 100watt head, made by Marshall with 2 channels, sharing an EQ, but with individual gain, reverb and volume controls, it has an effects loop and line out, 2 loudspeaker outputs with switchable ohm's, and a 50/100watt Switch. This amp is a beast pumping out craploads of oldschool metal heaven. // 10