As soon as you set eyes on OX UK’s OX-G400 amp head and speaker combo, you know you’re in the company of something a bit special. Everything about this thing’s design aesthetic suggests that this is no ordinary amplifier. This isn’t just an amp that’s been designed to look good, however, in fact this is a case of both brains and beauty.

SHERMAN AMP!
The first really significant thing about both the housing of the amplifier and the four-by-twelve speaker cabinet, is that rather than being manufactured from anything as utilitarian as wood, everything here is made from weapons grade metals, well kind of… Both the amp-casing and the cabinet are constructed from huge sheets of cast aluminium, and we’re not talking tin foil here. The panels on both the amp and the cabinet are a couple of inches thick. Folk in the MI industry always like to talk about the ruggedness and roadworthiness of their newest product, but none of them compare to the OX-G400: you could take an AK47 to this bad boy at close range and still be able to bash out a pretty decent rendition of Smoke on the Water through it afterwards. Given the amp and cabinet’s bombproof build-quality, it’s not that surprising to learn that this particular set-up, along with all OX UK’s products, comes with a lifetime guarantee. Unless you intend taking it out to Basra, it’s a fair bet that you won’t be needing that promise, but it’s good to know that it’s there.

The unusual choice of construction materials with this amp and cabinet, however, has further benefits than simply making it as soft and bouncy as a Sherman tank. It all comes down to Newton’s Laws of motion. Anyone who paid attention in science lessons at school (oh, okay that’s none of us then) will know that for every force, there is an equal and opposite force. In the case of a speaker cabinet, this means that when the cone inside moves back and forward at high speeds, the baffle tries to move equally in the opposite direction. The pressure reduction inside the cabinet forces the back and sides to move, reducing the punchiness of the overall sound – this is why weaker ply cabinets don’t tend to have the same amount of kick as birch ones. The obvious solution is to make a cabinet with almost no give, that way the movement of all the speaker cones inside is directed outwards with minimum loss of power – the upshot is an amplifier that’s not only built like a Sherman tank but one that has the capability to sound like said tank driving through a tea shop… nice. Oh, by the way, there is a flip side to all this good news – the cabinet feels about as easy to carry as a Whale in a shopping trolley – it is very heavy indeed. Thoughtfully, OX UK have incorporated large wheels unobtrusively into the back of the cabinet, so rather than make like Geoff Capes and try lifting the thing, it’s simply a case of pushing it back onto its wheels and rolling it along – good luck on the stairs though!

MIXING AND MATCHING!
It’s no good having a smart-looking sports car, if it doesn’t have a powerful engine, so how about the power behind the OX-G400; the amplifier itself? Well, the good news is that everything with the amp is just as exciting as it is with the cabinet. Other than the same all-metal construction, the amplifier has three channels – clean, overdriven and ‘whooah that’s loud’! Each channel is selected via a metal footswitch, which again feels like it’s made from plutonium. One nice feature here is that you can add channels together rather than simply toggling between them, so that you could add the clean channel to the overdriven channel, if you wanted to add a little clarity to that wall-of-sound overdrive, for example. All three channels have the usual Volume, Gain, Bass, Mid and Treble and Presence controls. Incidentally, all of the EQ controls are active rather than passive, as OX UK believe this gives them a much broader sweep than traditional passive rotaries. Anyone who’s used an old amplifier, which starts sounding like a bowl of Rice Crispies when they start rotating the EQ and volume controls will be pleased to know that all the potentiometers used on the OX-G400 employ top quality conductive plastic or cermet tracks, which despite being considerably more expensive than traditional carbon-track potentiometers, all but eliminate this problem.

THE ENGINE ROOM!
Round the back of the amplifier, the first thing that gets the pulse racing are the warmly glowing valves, designed to be clearly visible through the mesh-style outer-casing. The power-amp section of the amplifier uses a unique two-stage configuration comprising a pair of EL84s in a self-biasing class A push-pull configuration. These generate the amp’s signature tone, while a second stage, which uses a whopping six KT88s, delivers a sonic buffalo stampede over a huge frequency spectrum – it’s all extremely impressive stuff. The second thing you’ll notice is that beneath each of the KT88 power-amp valves is a tiny LED screen with a reading on it, and then just above that, a small rotary control. When you buy a matched set of valves they are selected to have similar plate dissipation characteristics, however, these inevitably change throughout the life of the valve. This unique feature allows you to adjust these characteristics with each valve, so that they remain perfectly matched throughout their working lives together. It’s indicative of the incredible attention to detail that’s gone into making this amplifier. There are also a number of switches on the back panel, including a Definition control, which mixes a small amount of the clean sound into the high gain channel. There’s also a reverb switch, which adds a solid-state reverb circuit into the preamp stage, and a Bass Boost switch, which drops the lower cut-off frequency by 15Hz for some real trouser-flapping low-end. Perhaps the two most interesting controls here are a unique Harmonic switch, which cleverly changes the ratio of odd to even harmonics to give a more attacking and bright or smoother and more sonorous timbre and a Triode switch, which changes the power-amp valves between pentode and triode mode, reducing the power and giving the amp a mellower tonality. It’s worth adding that because of the all-metal construction of both components (amp and cabinet) and with the help of anti-vibration feet on the amplifier, microphonics (the vibrations between cabinet and amp that can have a detrimental effect on the amp’s circuitry – not to mention the lifetime of the components) are totally negated. As for those delicate valves, well along with the complete absence of microphonic problems, they’re also mounted in gold-plated ceramic chassis sockets. Believe us, these little glass fellas will be working at their absolute best.

CONCLUSION
This really is quite an exceptional amplifier. Take it from us, the sound is stunning, with a huge amount of incredibly directional low-end, a gut-punching mid-range and bright, but never harsh, higher frequencies. To put it simply, this is one of the best amplifiers we’ve heard in a long time. It’s also unbelievably powerful without being simply noisy -the Holy Grail of amplifier characteristics – an effortless ability to create sonic earthquakes without ever sounding as if it’s trying too hard. Of course, this sort of quality comes at a price, especially as these amps are built bespoke to you, the guitarist’s, specific needs (usually around 6 weeks from order to amp). If you’re looking for the ultimate guitar amp, however, that really will last you a lifetime, then OX should be able to make your dream come true - start saving those pennies.

HIGHS
All-metal construction improves tone and makes both amp and cabinet virtually indestructible
Two-stage power-amp for incredible tone and power, with bags of valve character
Lifetime guarantee with top-grade high spec components and build quality
Channels can be mixed and matched and not simply toggled for maximum range of tones
Unique Harmonic and Definition switches, as well as bass boost and solid state reverb
Amps custom-built to order based on player’s individual requirements
LOWS

Both the amp and the cabinet really are incredibly heavy; if you live on the fifth floor, use the lift!
This kind of build-quality and attention-to-detail comes with a hefty price tag

Article Links
Official website: http://www.oxamps.com.