Предусилители — Kondo Audio Note Japan G-1000i

Kondo Audio Note Japan makes the G-1000i, a two-channel line-level preamplifier, which the maker presents as its top line model and the model built to its highest specification. Its circuit is split between two boxes, a main unit and an outboard supply, and the catalogue places it above the G-700i and G-72i line preamplifiers.

Key specs that matter

Inputs comprise four RCA pairs and one XLR pair, with two RCA outputs and one XLR output. Gain is 25 dB and output impedance is 600 ohm. Frequency range is 10 Hz to 280 kHz through the unbalanced path and 15 Hz to 90 kHz through the balanced path. Noise is below 0.15 mV, and the balanced input is transformer-coupled rather than a fully balanced circuit. The valve complement is four 6072 and two EZ81. Power consumption is 41 W. The main unit weighs 17 kg and the power supply 20 kg.

Engineering and use context

Level is adjusted with a newly developed 50-step attenuator. The line stage uses 6072 triodes in a direct-coupled arrangement of plate follower and cathode follower, avoiding a coupling capacitor between the two. Signals arriving at the XLR input pass through transformers wound with silver wire, which convert them for the single-ended circuit and explain the narrower frequency range of the balanced path. Groups of capacitors are distributed along the line stage, so that the supply has large reserve capacity while each signal loop stays short. Kondo uses its top-grade parts throughout - SSW silk-insulated silver wire, silver foil signal capacitors, and its own power transformer and choke. The heater supply is a newly designed shunt-type circuit with a 6CA4 rectifier valve, holding heater voltage within plus or minus 5 percent. Placing the power transformer, choke and rectification in the separate chassis keeps them away from the audio circuitry of the main unit.

Pairing

The low output impedance and generous gain let the G-1000i drive power amplifiers through either RCA or XLR connections, and the two RCA outputs allow a second amplifier to be run at the same time. Kondo power amplifiers such as the Melius, with 70 kohm RCA and XLR inputs, and the Ongaku, with 100 kohm RCA inputs, present light loads to this output stage. Up to five line sources can be connected, one of them through XLR, and the phono preamplifiers of the GE series, such as the GE-10i, can feed an RCA input for vinyl.

Alternatives

The Kondo G-700i is the next line preamplifier below it in the Audio Note Japan range.