Усилители мощности стерео — PrimaLuna EVO 200-4

The EVO 200-4 is a valve-only two-channel power amplifier made by PrimaLuna, part of the Durob group in the Netherlands, and it is placed in the second of the four tiers of the EVO power amplifier range. Like every EVO power amp it has a mono/stereo switch, which allows a pair of units to run as monoblocks. The US list price is USD 3,795.

Key specs that matter

With EL34 fitted, ultra-linear output is 44 W per channel in stereo, or 45 W with KT88, or 88 and 90 W in mono. Frequency response reaches from 12 Hz to 65 kHz within 1 dB and from 10 Hz to 95 kHz within 3 dB. THD is below 0.1% at 1 W in stereo and below 0.17% in mono, with under 2% at full output. Signal to noise ratio is 92 dB in stereo and 93 dB in mono. Input impedance is 100 kOhm, with 870 mV (EL34) or 880 mV (KT88) required for rated power. Maximum gain is 26.5 dB with EL34 and 29 dB with KT88. Power consumption is 280 W. The case is 405 x 365 x 205 mm and weighs 23 kg net.

Engineering and use context

Four EL34 output valves are joined by four 12AU7 driver and input valves. Bias is handled by Adaptive AutoBias, a sensor-based circuit that is passive, sits out of the signal path and addresses tube pinch-off at higher levels, with a switch for EL34 or KT88, KT120 and KT150 types. When a valve fails, the amplifier enters protection and a red LED marks the valve to replace. Output tubes run at about 417 V on plates and screens, and the listed compatible types run from 6L6G, 7581A and EL37 through 6550, KT66, KT77 and KT90 to KT120. Signal connections are hand-soldered point to point, and the handmade steel chassis carries a five-coat hand-polished finish. The power transformer is a custom potted toroid with a thermal switch that cuts the primary until it cools, the output transformers are custom-wound in-house, and SoftStart reduces thermal shock to parts. Nichicon and DuRoch polypropylene capacitors, Philips rectifier diodes and ceramic tube sockets are used, and the damping coefficient is 4 KD at 1 kHz.

Pairing

Connection is by one stereo RCA pair or one mono RCA input. Speaker taps of 4, 8 and 16 ohm are available in stereo, changing to 2, 4 and 8 ohm in mono, and the gold-plated terminals use solid shafts. No remote is supplied. Balanced XLR inputs, triode switching, Takman resistors and the AC Offset Killer circuit appear only on the EVO 300 and EVO 400 power amps.

Alternatives

PrimaLuna also offers the EVO 300-4, the next-tier stereo valve power amp with balanced XLR inputs.