Усилители мощности стерео — PrimaLuna EVO 300 Hybrid Amp

The EVO 300 Hybrid is a power amplifier from PrimaLuna that places valves in the input and driver stages and transistors in the output stage, a layout the company sums up as tube in the front, solid state in the back. It shares the 405 x 385 x 205 mm chassis size and 31 kg weight of the valve EVO 300 models, and a front switch turns it from a stereo amplifier into a monoblock. The US price was USD 7,195 for one unit, or USD 14,390 for a pair used as monoblocks.

Key specs that matter

In stereo mode PrimaLuna guarantees more than 100 W per channel into 8 ohm, typically 115 W, and more than 150 W into 4 ohm, typically 160 W. Bridged into mono, the ratings rise to over 220 W into 8 ohm and over 300 W into 4 ohm. Distortion stays under 0.2% at rated output, the frequency range is 10 Hz to 80 kHz within 3 dB, and noise sits 105 dB below reference, A-weighted. Voltage gain can be set to 30 dB or 24 dB. In stereo operation the RCA input presents 32 kohm and the XLR input 49 kohm, with sensitivity of 805 mV and 901 mV respectively, while in mono the figures change to 18 kohm and 50 kohm, and 1,330 mV and 1,340 mV. Damping factor at 1 kHz is 300 in stereo and 150 in mono. Mains draw is 104 W at idle and 645 W at full output into 4 ohm.

Engineering and use context

Six 12AU7 valves from PrimaLuna's Silver Label range sit on the front of the chassis - two work in the gain stages and four act as drivers. The output section runs push-pull in class AB, with cascaded JFETs from Linear Systems ahead of two complementary pairs of Exicon MOSFETs per channel, parts the company describes as custom made and hand matched. Each channel ends in a hand-wound, resonance-free output coil. Two separate inrush protection circuits soften the current surge at switch-on, and an AC Offset Killer circuit reduces mechanical noise from the power transformer. The 6 dB step between the two gain settings is switched by a dedicated relay inside the chassis.

Pairing

A single pair of RCA sockets and a single pair of XLR sockets accept the preamplifier signal, so balanced and single-ended line stages both connect directly, and a trigger connection allows remote switch-on alongside the rest of the system. The low stereo output impedance, specified at 0.026 ohm, and the power reserve into low impedances make the amplifier suitable for speakers of low or moderate efficiency. Owners who later add a second unit can bridge both for mono use.

Alternatives

Within the same series PrimaLuna also makes the EVO 300 Tube Power Amplifier, which uses valves in the output stage as well.