Усилители мощности стерео — TAD TAD-M700S

The TAD-M700S belongs to the Reference series of power amplifiers from TAD, whose full name is Technical Audio Devices Laboratories. It shares its enclosure and circuit concept with the monaural TAD-M700, and it places both stereo channels in one chassis instead of requiring a pair of monoblocks. TAD states that the basic idea behind both models is symmetry from input to output, uniting its proprietary technologies in a coherent whole. The monaural model differs mainly in output per chassis and in channel count.

Key specs that matter

Per channel, TAD rates the output at 175 W into 8 ohms and 350 W into 4 ohms at 1 kHz. Rated distortion is below 0.005 percent at 1 kHz with 175 W into a 4 ohm load, while noise sits at least 125 dB below signal, IHF A-weighted. The published bandwidth extends from 1 Hz to 100 kHz within plus 0 and minus 3 dB. Gain is 29.5 dB, and full output is reached with 1.5 V at the input, whose impedance is 100 kilohms. Power consumption is 590 W in operation and no more than 0.5 W in standby, with European versions running on 220 to 230 V at 50 or 60 Hz. The enclosure is 516 mm wide, 296 mm high and 622 mm deep, and at 75.5 kg the stereo model is one kilogram heavier than its mono sibling.

Engineering and use context

Both channels use a bridged transformerless circuit with full symmetry, operating in Class A/B. Matched FET pairs form the simplified input stage, keeping the number of amplifying parts low, and a DC servo circuit holds operation steady as temperature and input level vary. Two power transformers with hand-wound coils supply a combined rating of 2.8 kVA, and four custom 33,000 uF capacitors provide the energy reserve. TAD designed a new cast-aluminium monocoque chassis for this pair of amplifiers, choosing the material for its high internal loss factor so that sympathetic vibration at unwanted frequencies is suppressed. The wide footprint and slanted panels lower the centre of gravity, and the amplifier stands on four height-adjustable spike feet.

Pairing

The line-level TAD-C1000 preamplifier from the Evolution series is a matching TAD control unit and offers two balanced XLR outputs and two RCA outputs, so one unit can feed this stereo amplifier from its balanced connections.

Alternatives

The TAD-M2500MK2 from the Evolution series is another two-channel TAD power amplifier, using a Class D output stage rated at 250 W into 8 ohms.