Review of Marshall JCM900 Dual Reverb Guitar Amplifier

The Marshall stack has been the holy grail of rock guitarists since the sixties. Whether it be a full stack blaring metal or a half stack with the gain backed off for some Hendrix blues, Marshall has had claim on the sound of rock for decades. The JCM series of Marshall amps has had a long illustrious career since the JCM800 back in the 80s. The Marshall JCM900 Dual Reverb is not different. Full of tone and plenty of wattage, it is perfect for all types of rock.

The 4500 series of the JCM900 is an all-tube two-channel 50 watt amp head comes loaded with two EL34 output tubes and 3 12AX7 preamp tubes providing the Marshall growl we all know and love. The channels are marked as Channel A and Channel B each with its own volume, gain, and reverb controls. One drawback however is that they share the same EQ. But it is possible to strike a balance that will work for both channels and that will suit your playing style and musical tastes.

The two channels are switchable via the Channel switching button located on the front panel but they can also be controlled by a single button Marshall footswitch pedal. Channel A has considerably more headroom but still breaks up early. However you will notice that the distortion of the A channel is much lighter and works well for most classic rock and some modern rock tones. It has plenty of bite but is not over the top.

The B Channel is a different story. Here you will find pure unadulterated Marshall crunch. If you play hard rock or metal you will be happy with this channel. It breaks up early and it breaks up extensively. It may be possible to get some classic rock tone at very low settings with this channel, however you will find that this channel is best for cranked distortion.

There are a few ways you could use these two channels. Probably the most common set up is to use the tamer A Channel as a rhythm channel. You can also clean things up on Channel A by rolling back the volume on your guitar. Then when it times for those lead breaks switch to the B Channel (which you can have set to a slightly higher volume). Or if you play with a group in which you need different levels of distortion for different songs or parts of songs, then you can also employ the two channels for that kind of set up as well.

Looking at the back panel of this amp you will find that it comes with a High/Low switch for those times that you may or may not need full output. Switching to Low output cuts the delivered wattage in half (25 watts). You also get an impedance selector switch (be sure to properly match impendence to that of the speaker cabinet you will be using or you risk doing damage to the amp or your cabinet). The JCM 900 Dual Reverb also features dual output jacks for connecting two speaker cabinets (for those who need full stack rock goodness). Finally this amp has direct output jacks for recording and an effects loop for running filtering/modulation effects (though they can also be run into the instrument input jack on the front as well).

All in all this is an extremely versatile amp that handles a myriad of recording and live situations, tonal and output needs, playing styles, and genres of music. If anything ever happened to my JCM 900 I would definitely seek out another one to replace it. Great deals for this amp can be found on eBay so start browsing and pick one up. It will deliver the tone and quality that has made the Marshall name so famous.