Предусилители — Luxman C-700u

The C-700u is a line-level control amplifier from Luxman positioned in the middle of its preamplifier range. It carries over technology from the higher C-900u and has no phono stage, headphone output or digital section, handling only analogue line signals.

Key specs that matter

Rear connections comprise two XLR sockets and five RCA line inputs, plus a loop-through, a recording monitor and an external preamplifier input. Outputs include unbalanced and balanced lines and a recording feed. Input sensitivity is 250 mV on both input types, with input impedance of 46 kohm unbalanced and 67 kohm balanced. Nominal output is 1 V, reaching up to 11 V unbalanced and 11.5 V balanced, from 90 ohm and 600 ohm output impedances respectively. Response is flat within 0.1 dB from 20 Hz to 20 kHz and within 3 dB from 5 Hz to 120 kHz. Distortion is 0.007% unbalanced and 0.010% balanced from 20 Hz to 20 kHz, while IHF-A weighted signal to noise is 125 dB unbalanced and 122 dB balanced.

Engineering and use context

The LECUA 1000 sets the level. It is an electronically controlled attenuator with 88 steps covering 0 to 87 dB, up from 72 steps in earlier designs. Amplification uses the ODNF 4.0 feedback circuit, with quadruple parallel devices in the main stage and triple paralleling in the error detection section. The supply is built around an OI-type transformer and two 3,300 uF block capacitors. Tone controls give plus or minus 8 dB at 100 Hz and 10 kHz, and a line straight mode is provided alongside loudness. The balanced inputs can switch phase. A fluorescent display offers a four-level zoom and a dimmer. The chassis follows a loopless layout with a three-dimensional preamplifier arrangement to shorten signal paths, and it stands on cast-iron isolator feet. Power consumption is 28 W, or 2.0 W in standby. The case is 440 x 130 x 430 mm in size and the weight is 14.6 kg. Supplied accessories are the remote handset and a power cable. Custom resistors, capacitors and internal wiring are used throughout.

Pairing

The RA-22 remote covers input selection, volume, output mode, balanced phase, recording output, loudness, mute and display zoom. Both XLR and RCA outputs make it straightforward to drive a balanced or unbalanced power amplifier, and a turntable needs its own external phono amplifier.

Alternatives

The Luxman C-900u is the higher-positioned line control amplifier whose technology the C-700u inherits.