Усилители мощности моно — Aries Cerat Concerto 25

The Concero 25 is a single-ended mono amplifier of the Prestige Series from Aries Cerat. It is built around the 845 directly heated triode and priced at GBP 24,950 per pair with Elrog 845 tubes, while a 60 W version using the Elrog 846 costs GBP 13,000 more. Each channel is a separate chassis.

Key specs that matter

Per channel, one Elrog 845 output tube is driven by an RCA 814. Output is 20 to 25 W depending on the bias setting. The output transformer has selectable 2, 4 and 8 ohm taps and is rated for 60 W at 20 Hz. Gain is 1 times as standard, with a medium-gain option of 7 times, and the noise floor is below -100 dB A-weighted. Two toroidal transformers of more than 900 VA combined feed the supply, with separate supplies for the driver, the output stage, the filaments and the bias, choke filtering and more than 4,000 J of stored energy per channel. Idle consumption is 200 W. Each amplifier is 550 mm wide, 430 mm deep and 280 mm high, with an unpacked weight of 65 kg.

Engineering and use context

The 845 is a large transmitting triode with a directly heated filament, and in a single-ended stage one tube per channel handles the whole signal in Class A. This transformer rating, more than twice the amplifier's output, means the core will not saturate at full power in the deepest bass. The filaments are powered through triple PI CRC filters, a chain of capacitors and resistors that smooths the supply to the directly heated cathode, which carries the signal in this type of tube. Built-in digital displays show the driver and output bias, and both settings can be changed during operation. The standard gain of 1 means the amplifier adds no voltage gain, so it relies on a preamplifier with a high output, such as Aries Cerat's own preamps, and the medium-gain option suits sources with lower output. Separate supplies for each circuit section keep the driver and output stages from affecting each other through the power rails.

Pairing

With its modest power, the Concero 25 is matched to efficient loudspeakers, for example horn designs or large high-sensitivity towers, and the output taps match it to their impedance. A preamplifier with high output voltage is needed with the standard gain. Each heavy chassis runs hot and needs ventilation.

Alternatives

The Aries Cerat Concero 65 Reference is the larger single-ended mono amplifier, using an 814 driver and two 813 output tubes per channel for 65 W.