Mercury Magnetics Modified Amplifier Shootout: Epiphone Valve JR

With the amps set at roughly 10 o’clock you can already hear a real difference between the heads. The stock amps sounds all right when you first plug into it, especially when you look at its price point. But as soon as you switch to the Mercury Modified head you hear just how much of a difference the modification makes. It is not just the over all volume that has changed, it is the fullness of the tone. The signal sounds full and rich, and the string-to-string definition leaps out at you. If you simply focus your attention to the bridge pickup, you can hear how much more pleasing the Mercury head is to the ear. The stock JR feels choked and thin and to my ears, the break up is harsh. Like the microphone that is recording the guitar distorting, as opposed to the distortion coming from the amp.

There is nothing like a little Led Zeppelin to help you illustrate a point, in this case “Custard Pie” was just right. With the amps set half way, or 12 o’clock, the high frequency clarity of the Mercury really stands out. This is most apparent when you are in the bridge pickup; the stock amp sound very mid-rangy and almost muffled, like there is something covering the speaker cab. When you switch to the Mercury the sound is immediately more open and clear. The additional high frequency that you can hear is really amazing. The bridge pickup shows you how tight the sound can be, and the overdrive sounds just right to me.

It is interesting when you consider how good the stock Valve JR sounds on its own. The amp is not too bad at all, you can get some good tones out of it and it is loud enough for recording or maybe a small club. But as soon as you put it head to head with the modified version, you hear just what it is missing – harmonics and dynamic range. The ZZ Top lick really helps to illustrate my point, you can hear just how rich the harmonics are when Phil switches over to the modifier head. The same riff played on the stock head just doesn’t seem to produce the same amount of harmonics, and generally sounds dull and flat to me. I think this volume on the amp, between 2 and 3 o’clock, produces the best tone for the amp. It is the perfect tone for blues and rock. You could always throw in a boost pedal if you wanted to push the amp a little harder for increased sustain.

The last setting we compare on the amp is the obligator “maxed out.” At the max setting both amps are easily distorting and have a good amount of gain. I find that this setting is a little overboard in that the tone looses some of the detail and richness. You can still hear the added complexity that the Mercury Modification adds along with the top end richness, but the gain seems to overwhelm the tone. I think that the optimal setting for the amp is at 2 – 3 o’clock, that is where the amps sounds the most full and detailed. A boost pedal would be perfect if you were looking to pull some more gain out of the amplifier. 

In the end I think that the difference between the stock amp and the modified amp is very easy to hear. And it is based on that fact that I think this is such a great product, you hear the benefits without the need to really concentrate on what you are hearing – it jumps right out at you. The modification takes an amplifier that sounds good when you look at its price and transforms it into something that is unbelievable for the price. The modified Valve JR is an amplifier that you will play for hours and hours without any listening fatigue and I highly recommend that you check it out.

Be sure to check out our second shootout between the stock Epiphone and the Mercury Modified Epiphone with Mike Sopko playing a LSL Telecaster to coax some sweet vintage tones out of the amp.