Усилители мощности моно — Karan Acoustics POWERa STEREO

The POWERa STEREO is a two-channel transistor power amplifier from the Karan Acoustics Master Collection, a range that took about ten years to develop at the Novi Sad company Milan Karan set up in 1986. It arrived alongside the POWERa MONO and became available in December 2021 at EUR 39,000, with a US price of USD 53,000 quoted later. Despite being a stereo unit, it uses a dual-mono internal layout.

Key specs that matter

Rated output is 650 W per channel into 8 ohm and 1,100 W into 4 ohm, all across 20 Hz to 20 kHz. Output into 2 ohm is given as 1,800 W to 2,000 W per channel. Full output is reached with 2.0 V at the input, and each channel accepts balanced XLR or unbalanced RCA signals at 30 kohm input impedance. Response is flat within 0 dB from 20 Hz to 20 kHz, following the same DC to 300 kHz bandwidth at the 3 dB point as the monoblock, and THD and IMD are both 0.03 percent. Karan puts noise more than 120 dB below full output. At launch it cost roughly half of a POWERa MONO pair, which gives 2,100 W per channel into 8 ohm.

Engineering and use context

Karan builds the topology as fully differential and runs a sliding Class A bias that follows the amplitude of the incoming signal. Sanken bipolar devices form the output stages. Power comes from twin toroidal transformers of 2.1 kVA each, one per channel in the dual-mono arrangement, feeding a capacitor bank of 210,000 microfarads, and a switchable line conditioner is built in. Two 15 A mains cords are needed. Passive parts include Vishay resistors and Audyn capacitors, internal wiring is pure copper from Cardas Audio, and the RCA sockets and speaker posts are WBT Nextgen. The chassis is the same as the monoblock version, measuring 504 x 292 x 603 mm and weighing 105 kg, CNC-machined as an aircraft aluminium unibody and standing on Critical Mass Systems CSA2 isolation feet. With both channels in one enclosure, a stereo system needs one amplifier stand instead of two, and a single set of CMS feet, while keeping separate transformers for left and right.

Pairing

A preamplifier with balanced outputs suits the input sensitivity, and the high output into low loads keeps low-impedance loudspeakers within the amplifier's stated range.

Alternatives

The Karan Acoustics POWERb STEREO is the smaller two-channel power amplifier in the same Master Collection, positioned below the POWERa STEREO.