AUDIO RESEARCH LAUNCH GALILEO SERIES VALVE AMPLIFIERS
Brandon Lauer of Audio Research Corporation talks to the press about their new Galileo Series amplifiers.
Noel Keywood visits KJ West One to see new Audio Research valve amplifiers.
Friday 5th December 2014, London, UK.
Audio Research of the USA recently launched a new range of amplifiers, the G Series, named after Galileo they say. I got first sight and pictures of the new 150 Watt per channel GS150 valve power amplifier, Friday 5th December at dealer KJ West One, Wigmore Street, London. It was driven by a GSPre preamplifier. You can see the GS150 nestling on the floor in our top picture.
From Minneapolis, in the state of Minnesota, came Brandon Lauer of Audio Research Corporation, to explain to assembled members of the press the thinking behind this new series. Let me explain quickly that Audio Research amplifiers have a particular and well managed approach to sound quality that not everyone gets. They use tubes (valves), but in a way that extracts a fast and punchy sound with seemingly greater dynamics than you'll find anywhere else. When I say "in a way" I mean with transistors! Brandon interestingly re-iterated this point to assembled journos.
Yes, Audio Research combine tubes with solid-state to get a hybrid sound, as it were. It's also possible to extract better performance figures this way, as well as provide remote control and automated functions. Here's a quick look at the lovely, meter be-decked GS150 power amplifier you can see in the picture, to illustrate the point.
The GS150 power amplifier. Meters at left and right show power, the one in the centre mains volts. The knobs adjust bias, and this is indicated by the meters as well.
The input stage uses a hybrid FET/tube input we were told. It amplifies and phase splits, feeding 6H30 driver tubes that couple to the new KT150 power output tube - well, four of them working in parallel push-pull. This is the working end of the amp, as it were - and the interesting bit that says it all. The KT150 power tube is relatively new, a year or so old. It has been crafted to deliver a smoother and more sophisticated sound than its predecessors, the extended-power KT90/120, that both sounded a tad clanky and crude. Only trouble is, the KT150 is expensive, think £100 apiece, so any amp using them isn't cheap; £400 for output devices is quite a bill.
A push-pull pair of KT150s can deliver around 75 Watts in fixed bias mode, so the 150 Watts power figure of the GS150 is as expected, and it uses fixed bias, like all Audio Research tube amplifiers, for maximum power output. Fixed bias does mean, by the way and confusingly, that bias needs occasional adjustment. The meters facilitate this task, or can be switched to show power output. The centre meter shows mains inout volts that ideally should be in the green target area for quoted outputs to be achieved, but this issue, which also affects solid-state amps, is of little subjective consequence.
Around the back is an RS232 computer interface, I found, so the amp can send a handshake signal back to an external domestic control system, and it accepts a 12V trigger. So this is a tube amp for a thoroughly modern home system, illustrating the approach of Audio Research to tube design. And what you get is a thoroughly modern sound too, as well as absolutely no hum or noise Brandon Lauer pointed out to us, stooping to place his ear near the cones of a pair of Wilson Audio Sasha 2 loudspeakers, to make the point.
The GSPre preamp is again a hybrid design, but it predominantly uses 6H30 tubes - chunky double triodes - in its line stages, and in a tube phono stage. But here Audio Research also use an FET input for low noise - important for MC cartridges. The preamp has balanced inputs and outputs and it feeds the GS150 through a 6H30 balanced, tube line drive stage, Audio Research say. Again, there's full home automation control via RS232, as well as infra-red control.
So the Galileo amplifiers use thoroughly modern design principles, even though they use tubes. Audio Research were excited to be using the new KT150 they said, as it offers exactly what they want from a valve amplifier when used in modern circuits. Coming later is a GSi75 integrated amplifier.
Audio Research comes into the UK through Absolute Sounds, who organised this event and provide service and backup. Prices are to be announced.
Noel Keywood, publisher.