Предусилители — Perreaux SM6 Mkll

The SM6 MkII is the balanced stereo preamplifier of the Prisma series from Perreaux Industries, whose base is at Mosgiel near Dunedin in New Zealand and whose production began in 1974. It is a solid-state, discrete design with Class A operation in every stage, built for analogue sources only and Perreaux pitches it as a match for the Perreaux 350 and 750 power amplifiers. Pricing is NZD 9,495 in New Zealand including GST and GBP 4,500 in the UK, and the front can be black or silver anodised or painted to order.

Key specs that matter

Rated output is 1.5 V RMS, and maximum output reaches 3.3 V RMS unbalanced or 6.8 V RMS balanced. Input impedance is 10 kohm on RCA and 20 kohm on XLR, sensitivity is listed as 200 mV, and overload occurs at 3.9 V or 7.8 V. Response is flat to within 0.03 dB from 20 Hz to 20 kHz and within 0.15 dB from 10 Hz to 60 kHz. THD+N at rated output stays below 0.004% across the audio band, with a typical 0.001% at 1 kHz. Unweighted signal-to-noise is 95 dB unbalanced and 100 dB balanced, dynamic range is 116 dB, and channel separation reaches 105 dB at 1 kHz on the balanced path. The chassis is 430 mm wide, 106 mm high and 323 mm deep and weighs 7.7 kg net, and power draw is 50 W running or 0.5 W in standby.

Engineering and use context

Non-inverting and inverting signal legs never meet anywhere between input and output. Four discrete Class A output buffers let the unit drive low impedance loads over long cable runs. Six regulated supplies are fitted - one for each of the two volume chips, one for each balanced output stage, one for the digital logic and one for the input relays - so digital noise stays out of the audio circuits. Volume uses two digitally controlled resistor ladders with 60 steps of 1.5 dB, running from -97 dB to +18 dB, which avoids wiper contacts and component drift. Signal and power earths meet only at one star point. There are six RCA input pairs and one XLR pair, with input A switchable between them. Two RCA preamp pairs wired in parallel and one XLR pair feed amplifiers, while two RCA line pairs serve recorders and are cut when their own input is selected to prevent feedback loops. Input D acts as a home theatre bypass fixed at 0 dB. Two 3.5 mm trigger jacks deliver 5 V at up to 10 mA.

Pairing

The parallel preamp outputs allow bi-amping or a powered subwoofer without splitters, and the balanced output suits any power amplifier with XLR inputs. The 36-button infrared remote handles standby, mute, volume, balance, display and input choice.

Alternatives

Perreaux also built the Silhouette SXP2, a compact passive preamplifier with an ALPS potentiometer and dual preamp outputs.