Усилители мощности моно — Accustic Arts MONO IV

The MONO IV is a single-channel power amplifier that Accustic Arts Audio GmbH builds by hand in Germany and places in its reference class. It uses the same 340 x 470 x 440 mm case as the stereo AMP IV, but the entire chassis is devoted to a single channel, so two units are required for stereo playback. In the United States it has been offered at USD 69,990 with chrome trim and USD 72,990 with gold trim.

Key specs that matter

Rated output is about 510 W into 8 ohm, 760 W into 4 ohm and 900 W into 2 ohm. Voltage gain is 30.0 dB. The balanced XLR input presents 2 x 20 kohm and the unbalanced RCA input 100 kohm, which is an unusually light load for a source or preamplifier. The quoted noise figure is 96 dBA, THD+N is 0.004 percent and intermodulation distortion is 0.007 percent, both measured into 4 ohm at 10 W. With no signal the amplifier draws about 120 W from the mains. The unit weighs around 42 kg and arrives in a flight case that adds another 12 kg.

Engineering and use context

All 20 selected MOS-FET output transistors work on one channel, whereas the AMP IV divides the same number between two. Power comes from two toroidal transformers, each magnetically shielded and encapsulated, with a maximum combined rating of 1200 VA, and the reservoir bank holds more than 80,000 uF in capacitors made in Germany. Accustic Arts specifies a high damping factor for control of the woofer cone. A protection circuit guards against clipping, RF oscillation and excessive DC offset at the output. Both input types are fitted, and a rear-mounted switch picks the active one, so the amplifier can stay connected to two different sources of signal. The housing is massive aluminium chosen for stiffness and low resonance, and the front carries an inlay of solid brass that is polished to a high gloss and then chromed.

Pairing

Its low minimum load means the MONO IV accepts loudspeakers whose impedance falls well below nominal, including large multi-way towers with several parallel woofers. The WBT terminals are gold-plated and doubled for bi-wiring, and with four monoblocks each speaker can be bi-amped. Line stages with balanced outputs can use the XLR route, while the high-impedance RCA input lets tube line stages with a higher output impedance drive it without strain.

Alternatives

The Accustic Arts MONO VI is the bigger monoblock of the brand, rated above 950 W into 8 ohm and weighing about 74 kg.