Предусилители — TAD TAD-C700

The TAD-C700 is a line-level preamplifier in the Reference Series of TAD Labs, announced on 25 April 2024 with deliveries from June 2024 at USD 68,500 or CAD 94,500. It takes over from the TAD-C600, which had been launched in 2011, and TAD describes it as a set of refinements to the preamplification circuit, the dual-mono build, the power supply and the vibration control of the earlier model. The circuit is fully balanced and is split across two separate cases.

Key specs that matter

Four balanced XLR and two unbalanced RCA inputs are fitted, feeding two balanced and two single-ended outputs. Rated output voltage is 1.5 V balanced and 0.75 V unbalanced, while maximum output reaches 20 Vrms balanced and 10 Vrms unbalanced. Input impedance is 100 kilohm on the XLR sockets and 50 kilohm on RCA. TAD specifies a 10 Hz to 100 kHz response within 1 dB along with 120 dB S/N. Power draw is 52 W, falling to 0.5 W or less on standby. The main unit measures 450 x 150 x 440 mm and weighs 29 kg, and the power supply case is 220 x 185 x 430 mm at 15 kg.

Engineering and use context

Attenuation is handled by a custom electronic volume control based on ladder-resistance switching, adjusted independently for each channel. TAD quotes an absolute error of 0.1 dB or less even beyond 100 dB of attenuation, and distortion under 0.0005% at 1 Vrms input. After the volume stage the signal passes through a single-stage current-feedback voltage amplifier and goes straight to the outputs, and each of the two line outputs has its own amplifier circuit so that the signal is never branched between them. The outboard supply uses a 400 VA toroidal transformer, a rating TAD notes is usual for power amplifiers but not for preamplifiers, inside a cast aluminium monocoque. Keeping it in its own case stops transformer vibration and magnetic flux leakage from reaching the audio circuits. The main boards are mounted on a 33 mm pure aluminium sub-chassis weighing 15 kg, and three-point spike feet support the unit.

Pairing

A recording output with bypass and a pass-through mode are provided. A MASTER OUT jack lets several C700 units be controlled together, and a system remote is supplied. The high balanced output ceiling leaves wide margin for any power amplifier input, and mains versions cover 120 V in the United States and 220 to 240 V elsewhere.

Alternatives

The TAD-C1000 is the analogue line preamplifier of the Evolution series, offering the same arrangement of four balanced and two unbalanced inputs.