Tube Audio Amp

When it comes to guitar amps, vacuum tubes are a given. I've heard and played some amazing solid state amps and digital simulations, but so far I haven't been convinced enough to consider using one in a "serious" situation, other than for the convenience. But what about audio? I hadn't owned or regularly used a tube audio amplifier in many years, so to satisfy my curiosity I bought a simple kit and put it together ... and was promptly blown away.

Just Three Tubes = Seriously Impressive Sound

There's a company by the name of "Elekit" (you can find 'em on the web) that makes a variety of electronic kits, ranging from beginner projects through tube amps like the one I'll describe here.

Here's what's in the box.

The chassis, circuit board, and parts are all of surprisingly high quality, and a decent set of tubes is supplied. The manual (at least the Japanese one I received with my "domestic" version of the kit ... I can't vouch for the international versions) is comprehensive, clear, and well laid out.

This is definitely not a kit for the first-time or inexperienced builder, but if you're confident with a soldering iron and basic tools it goes together smoothly and relatively quickly. I took it slowly and, working around multiple breaks, interruptions, and outside engagements, had the amp up and running in just two days.

It's a simple amp. Just two stereo line input pairs (switchable), a power switch, and volume control. But the sound is very impressive, and maybe that is partly because of its simplicity. It does have a few notable circuit features that probably help as well. The power supply is always important, and the one in this little amp is well designed around an "R-core" transformer and has ample capacity. High quality components, an effective ripple filter, and a chassis design that provides excellent shielding contribute to a high signal-to-noise ratio. The supplied Electro Harmonix 12AX7 preamp (dual triode) tube and 6L6GC power tubes are proven, high-performance types and, although you can replace them with KT88, KT66, or EL34 tubes if you prefer the subtle tonal variations they provide, I have been quite happy with the supplied 6L6s.

Rated power output is 8.5 watts per channel into 8 ohms which, from a tube amplifier, is more than enough for normal listening. Two speaker outputs per channel allow the amp to drive speaker impedances from 3.2 ohms to 16 ohms. Frequency response is 20 Hz through 43,000 Hz (-3dB).

Not much use in a multi-channel surround home theater setup, but great if you just want well-balanced, clear, detailed stereo sound. And it's affordable too! Nice.