Lehmann Audio Decade

The Lehmann Decade is a phono preamplifier designed by Lehmann Audio to sit between the Black Cube SE II and the Silver Cube, the manufacturer's two other flagship models. It is intended for amplifying and correcting the signal from a cartridge, whether MM or MC type, before it passes to a preamplifier or integrated amplifier.

The unit takes the form of two chassis of the same size, one for the preamplification stage and one for the power supply, both made from a specific non-magnetic aluminium alloy treated against resonance to limit microphonic effects. The circuit incorporates input stages derived from the professional world, similar to those used in the microphone preamplifiers of studio consoles. RIAA equalisation is handled by an entirely passive network, built with MKT capacitors and high-precision, low-tolerance, low-noise metal-film resistors.

Three micro-switches on the front panel allow selection of the subsonic filter, gain and MM/MC position. They control precision relays that switch the different values. Gain and impedance are adjustable independently of one another, allowing extensive compatibility with a wide range of cartridges on the market.

The power supply, named PWX 2, is deliberately oversized relative to the circuit's actual requirements. It is built around a 30 VA toroidal transformer fitted with an earthed winding, isolating the primary from the secondary. Filtering relies on high-value electrolytic capacitors, complemented by a precision regulation circuit ensuring a stable voltage.

This preamplifier is aimed at analogue playback enthusiasts who already own a turntable fitted with an MM or MC cartridge and who are looking for a separate phono stage, finely adjustable to the cartridge in use, rather than a phono stage built into their preamplifier or turntable.