Published On: Mon, May 17th, 2010

Electro-Harmonix Caliber Power Amp

The latest devices from the ever-insane Electro-Harmonix are a vintage delay/chorus/vibrato and a power amplifier that you can fit under your hat. Review by Huw Price

Electro-Harmonix pedals have traditionally taken up large areas of real estate on our pedalboards, but recently there’s been a trend towards downsizing. The Big Muff, Metal Muff and Q-Tron have spawned the Little Big Muff, Micro Metal Muff and Micro Q-Tron, and now the Memory Man has sired the Memory Boy. As for the 22 Caliber, it’s taking miniaturism to the extreme!


Who ever heard of a stompbox without a footswitch? The reason is simple – the 22 Caliber isn’t a stompbox nor even an effects pedal. It’s actually a 22W power amp that you can fit inside your pocket.


You’ve probably figured out already that valves aren’t on the menu. This is a solid state device using Class D technology – but ‘D’ doesn’t necessarily stand for digital. Class D amps employ the switching mode of transistors to regulate power delivery. They’re very efficient, so they don’t need heavy heat sinks, and small inductors can be used instead of large audio transformers.


Class D amps have often been used in budget audio systems like small surround sound installations, but as the technology improves they’re also being used in active studio monitor speakers, where they are sometimes credited with having valve-like characteristics. This is obviously good news for a guitar amp wannabe.


There are only two controls; a Volume and a Bright switch that adds a subtle high frequency boost (or perhaps shifts the low pass cutoff frequency higher up the audio spectrum). The 22 Caliber ships with a dedicated 18W DC power supply and you’re advised to ensure that the output is connected to a speaker cabinet before you connect it up.


Ideally, the 22 Caliber likes to see 8 Ohms. It will drive any cab rated 4 Ohms to 16 Ohms, but it may struggle to drive loads under 8 Ohms at higher volume settings and may automatically shut off to protect itself.


Similarly, if you connect the 22 Caliber to a cabinet while it is already powered up, the output may automatically mute itself; if this happens, disconnect the power, wait a few seconds then power back up. Electro-Harmonix also recommends that the cabinet rating should be at least 30W. Needless to say the output of the 22 Caliber should never be connected to the input of a guitar amp or an effects pedal.


Wattage figures should always be taken with a pinch of salt, as they seldom offer any reliable indication of loudness. For instance my modded Vox AC10, which probably pumps out between 15 and 18W, was louder than the 22 Caliber when fed to the same Celestion G12H speaker. Having said that, the 22 Caliber is very loud; certainly loud enough for gigging.


However, the quality of the sound is the big surprise. I was expecting the usual dry and lifeless tone of a budget solid state amp but the 22 Caliber sounds more like a tweedy single-ended valve amp. It’s a bit rough around the edges, but it has a simple charm that encourages you to keep playing.


Overdrive kicks in between 11 and one o’clock on the volume control, depending on whether you’re using humbuckers or single coils. Things also get progressively brighter as you turn up, so the Bright/Norm switch comes in handy to take the edge off the crunch. Personally I preferred using the 22 Caliber with just a hint of breakup in conjunction with an overdrive pedal.


The 22 Caliber is great fun but I have to ask the question - what's the point? Granted, E-H has managed to create a miniature guitar amp, but there are plenty of small amp heads out there and your speaker cabinet will still be just as big and heavy as it ever was. The 22 Caliber sounds decent enough but it doesn't really compete with a small valve amp for tone or playing feel. Still, it would make a great backup if you gig with a vintage amp - and you could keep it in the glove box of your car for emergencies.

Build Quality Playability Sound Value Vibe Score
16 14 13 18 14 75

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