Integrated amplifiers — PrimaLuna EVO 400

The EVO 400 Integrated is an all-valve stereo integrated amplifier from PrimaLuna, the Dutch brand owned by Durob, and it heads the four-tier EVO range of integrated models. Its US price is USD 6,495, and it is hand-built in a heavy-gauge vented steel chassis whose finish is built up from five hand-polished coats.

Key specs that matter

Output in ultra-linear mode is 70, 72, 85 or 88 W per channel with EL34, KT88, KT120 or KT150 output tubes respectively, and 38, 40, 45 or 50 W in triode mode. Frequency response is 9 Hz to 50 kHz within 1 dB and 8 Hz to 68 kHz within 3 dB. THD is below 0.1% at 1 W and below 2% at rated power, while S/N sits between 90 and 98 dB with A-weighting. Input impedance is 100 kOhm, with sensitivity of 320 to 370 mV for rated power at maximum volume. Maximum gain is 36.9 to 37.5 dB in ultra-linear and 36 to 36.5 dB in triode. Power draw ranges from 470 W to 550 W by tube type. The unit measures 405 x 385 x 205 mm and weighs 31 kg.

Engineering and use context

The standard tube complement is eight EL34 power tubes with six 12AU7 small-signal tubes. Adaptive AutoBias monitors and adjusts bias continuously from outside the signal path, and if a tube fails the amp switches to protection with a red LED showing which one. A high/low bias switch covers EL34 and KT88 families. Triode and ultra-linear modes can be switched from the full-size metal remote. The signal path is point-to-point wired with Swiss silver-plated OCC copper in Teflon, and Takman resistors, a motorized ALPS volume control and Nichicon and DuRoch capacitors are fitted. Custom potted toroidal power transformers carry the AC Offset Killer and PTP thermal protection, output transformers are wound in-house, and SoftStart eases stress on parts at power-up. The damping coefficient is 7 KD at 1 kHz. Tube sockets are ceramic, and the WBT-style speaker terminals are gold-plated with solid shafts.

Pairing

Five stereo RCA inputs are joined by a home theater input. Speaker taps for 4 and 8 ohm loads sit beside a tape out and a subwoofer out taken from the output transformer taps through a voltage divider, switchable between stereo and mono. The headphone output uses the full valve circuit rather than a separate chip amplifier. There is no internal DAC, and a shielded box on the bottom plate can house the PhonoLogue EVO, an optional MM phono board.

Alternatives

PrimaLuna also makes the EVO 300 Integrated, an all-valve integrated amplifier in the tier below.