Preamplifiers — Einstein Audio Components The Preamp

The Preamp is a fully balanced dual-mono valve line preamplifier built by Einstein Audio Components in Bochum as part of the Reference Series. The current version is listed as The Preamp MK18 at EUR 35,000. Its intended partner is The Poweramp, a Circlotron hybrid power amplifier, and the range also includes The Amp Ultimate MK108 integrated amplifier and The Silver Bullet MKII OTL monoblocks.

Key specs that matter

The balanced output delivers 2.5 V into 100 ohm, with an output impedance of 50 ohm. Maximum input is 7 V. Bandwidth extends from 7 Hz to 400 kHz, channel separation exceeds 98 dB, distortion is below 0.01% at 1 kHz and signal to noise ratio is about 100 dB. The circuit works without global feedback. The output stage uses four NOS PCC88 double triodes per channel, made by EI, and ten selected, paired valves are used in the input stages. The preamplifier measures 430 x 200 x 410 mm and weighs 20 kg.

Engineering and use context

The Preamp is a two-stage design. A discrete input and symmetry amplifier converts the signal to balanced form in a single stage, and the output stage is an impedance converter without voltage gain, built from the PCC88 triodes in a fully balanced, dual-mono arrangement. Input selection avoids switches, relays, FETs and integrated circuits entirely. Each input has its own valves, and an input is selected by switching on the heaters of its valves, so no contact sits in the signal path. The volume control is also placed outside the signal path. Each channel is built on its own low-resonance sub-frame isolated from the case, and all wiring is point-to-point. The power supply is stabilised and was redesigned for this version, and the larger case was optimised for resonance and heat. Input sensitivity is variable, which allows levels to be matched between sources and is also useful when two power amplifiers are used for bi-amping. The low output impedance lets the preamplifier drive long balanced cables to power amplifiers placed near the loudspeakers.

Pairing

The Preamp is designed for Einstein's The Poweramp, connected through balanced cables, and its variable sensitivity helps match other power amplifiers, including pairs for bi-amping. Line sources such as DACs, CD players and phono stages connect to its inputs.

Alternatives

Einstein Audio Components currently lists The Preamp as the sole line preamplifier across both its Reference and Shadow ranges.