Preamplifiers — Electrocompaniet EC5

The EC 5 is a stereo reference preamplifier from Electrocompaniet of Norway, the result of about ten years of development. It is a line-level design built fully discrete, balanced and dual mono, with every gain stage working in pure Class A and an independent power supply for each channel. The preamplifier was first presented to the public in Munich.

Key specs that matter

Bandwidth extends from 0.5 Hz to 450 kHz, and THD+N is below 0.0002 %. Maximum voltage gain is 20 dB, and the gain range covers -73 dB to +20 dB. Balanced input impedance is 47 kOhm and output impedance is 22 ohm. Both input and output handle up to 10 V RMS, DC at the output stays under 1 mV, channel separation exceeds 120 dB and the noise figure is 113 dB below 1 V, A-weighted. Each channel has four balanced and two single-ended inputs. Outputs comprise two balanced pairs and one single-ended pair, each with a record out. Control connections include Ethernet, USB for programming, two trigger inputs and three trigger outputs, and a selectable internal or external IR receiver. The unit is 470 mm wide, 420 mm deep including the volume wheel and ground terminal and 190 mm high with feet, and it weighs 26 kg. Power draw is 80 W idle and under 0.5 W in standby.

Engineering and use context

A fully electronic attenuator sets the level, and it needs no mechanical switches or relays. It moves in steps of about 0.1 dB, around 1,000 in total, and the electrical length, impedance and phase of the signal path stay the same at every setting, so the circuit a signal passes through at low volume matches the one at high volume. The circuit uses the AmpliWire topology from Electrocompaniet, which combines high bandwidth with a high slew rate, and it has no capacitors in the signal path. Two 80 VA toroidal transformers, one per channel, feed 15,000 uF of storage capacitance on each side, keeping the channels isolated from each other. A 17.8 cm display on the front shows status, and the preamplifier can also be run from an app over the network.

Pairing

With six stereo inputs and dual balanced outputs, the EC 5 is able to feed a pair of power amplifiers simultaneously, for example a pair of AW 300 M monoblocks in a bi-amped system. The balanced inputs suit sources such as the EMC 1 MKV CD player, and the trigger outputs can switch connected amplifiers on and off together with the preamplifier.

Alternatives

The EC 4.8 MKII is the other Electrocompaniet line preamplifier, a dual-mono, fully balanced unit built from discrete parts, with each channel fed by its own supply.