Power Drive
Sydney Morning Herald
Monday June 21, 2004
If you like loud, this amplifier combo motors along just nicely. Greg Borrowman reports.
It's no coincidence that the Accustic Arts factory (yes, that's Accustic) is located close to those of Mercedes Benz and Porsche in the south of Germany. Before setting up Accustic Arts in 1996, its founder and president, Fritz Schunk, was involved in the design and manufacture of industrial robots for the automotive industry.
Given his background, you'd be forgiven for imagining Accustic Arts amplifiers are produced on completely automated assembly lines and that its designs would
include the latest technical innovations. You'd be wrong
on both counts.
The unimaginatively named Preamp 1 and Amp 1 are built the old-fashioned way: by hand. Their components certainly represent the latest in solid-state technology, but the overall circuit topology is conventional, particularly in the power amplifier.
It uses eight standard MOS-FET output transistors whose power is supplied by a 750VA toroidal power transformer and 80,000 microfarads of smoothing capacitors.
Accustic Arts claims the Amp 1 will deliver 130 watts
into eight-ohm speakers, 190-watts into four-ohm speakers and 230-watts into two-ohm models.
It's difficult to achieve such high output levels while providing protection for the circuitry, so the Amp 1 has
a sophisticated protection circuit that senses output
stage clipping, high-frequency oscillation and excessive current draw. It shuts down the amplifier when it senses something's wrong.
One reason amplifiers sound different is because of back-electromotive force, or back-EMF. This occurs because once a speaker cone is moving, it creates its own voltage, which it sends back to the amplifier.
If the amplifier can't ignore this spurious voltage, the music it is amplifying and sending to the speakers will be changed. The ability of an amplifier to resist back-EMF is called its "damping factor" and is measured as a ratio.
The minimum acceptable ratio is 50:1, with most power amplifiers coming in at 500:1. The Amp 1's damping factor is 1000:1.
The matching Pre 1 looks the part, and comes with a handsome aluminium remote control rather than a tacky, plastic one, but it has only three unbalanced line-level inputs, too few for hi-fi buffs who play music from up to six different sources. There's also no phono input, so if you still use a turntable you'll need a separate phono pre-amplifier.
On test, the Amp 1 power amplifier did not deliver the power claimed for it. The Guide's independent test reported power output at 1kHz as 120 watts into eight ohms, 175 watts into four ohms and 174 watts into two ohms.
The Amp 1's protection circuit is also a little too clever for its own good, automatically limiting continuous power at higher frequencies so that, at a test frequency of 20kHz, maximum power output at eight ohms is just 15 watts, increasing to 30 watts into four-ohm loads, and 60 watts into two ohms.
In our listening sessions, the Accustic Arts pre/power combination performed faultlessly. The reproduced sound was free of harmonically related distortion, with no audible mains-frequency hum and no annoying high-frequency hiss. Stereo imaging was perfectly centred, so the gain of each channel is identical, which is a little unusual for a pre/power pair.
The Amp 1 may not have produced its claimed power on the test bench, but it proved to be more than loud enough for our purposes, even when driving inefficient speakers.
Infofile
Accustic Arts Preamp 1 & Amp 1
RRP: $7995 (Pre 1), $9095 (Amp 1)
Sensus Pty Ltd
PO Box 52, Vaucluse, NSW 2030
9388 8158
info@sensus.biz
www.sensus.biz
© 2004 Sydney Morning Herald
Share This