Усилители мощности стерео — PrimaLuna EVO 300-4

The EVO 300-4 is an all-valve stereo power amplifier from PrimaLuna, the brand owned by Durob in the Netherlands, sitting in the third tier of the EVO power amplifier range. A switch sets it for two-channel or monoblock use, and it adds triode and ultra-linear modes selectable from a remote. The US list price is USD 4,695.

Key specs that matter

Ultra-linear output reaches 44 W per channel in stereo with EL34 and 43 W with KT88, or 85 and 84 W in mono. Triode mode gives 22 or 25 W per channel in stereo and 45 or 50 W in mono. Frequency response covers 10 Hz to 70 kHz within 1 dB and 8 Hz to 75 kHz within 3 dB. THD is below 0.1% at 1 W and under 2% at rated power, and noise is quoted at 91 dB unweighted or 105 dB A-weighted. Input impedance is 100 kOhm, sensitivity for rated power is 870 mV with EL34 and 880 mV with KT88, and maximum gain is 26 dB or 29 dB. Consumption is 300 W, and the 405 x 385 x 205 mm chassis weighs 30 kg.

Engineering and use context

Standard valves are four EL34 power tubes and six 12AU7. Adaptive AutoBias runs outside the signal path and trims bias continuously, and a switch sets it for EL34 or the KT88, KT120 and KT150 family. If a tube fails, protection engages and a red LED flags the valve concerned, while a relay protects the output transformers, resistors and high-voltage supply. All signal connections are hand-soldered from point to point, and EVO 300 and EVO 400 models use Swiss silver-plated OCC copper with Teflon insulation in the signal path. Power is supplied by custom potted toroidal transformers fitted with PTP overheat protection, output transformers are designed and wound in-house, and SoftStart protects parts from thermal shock. The damping coefficient is 4 KD at 1 kHz, and Nichicon and DuRoch polypropylene capacitors with Philips rectifier diodes are used. Takman resistors from Japan and the AC Offset Killer circuit, which lowers transformer hum caused by DC on the mains, are also fitted. Plates and screens of the output tubes run at about 417 V, and PrimaLuna lists types from 6L6G and EL37 to KT120 and KT150 as usable.

Pairing

Inputs come as a stereo pair in RCA and XLR form, along with a single mono input in each format, so balanced preamplifiers can be connected directly. Speaker taps are 4, 8 and 16 ohm in stereo and 2, 4 and 8 ohm in mono, on gold-plated solid-shaft terminals. A slim remote handles the triode and ultra-linear switching.

Alternatives

PrimaLuna also makes the EVO 400 power amplifier, the all-valve model in the top tier of the EVO power amplifier range.