Предусилители — Kora PR140

The PR140 is the line preamplifier of the Kora 140 series and, as the control centre of a Kora system, it pairs with the brand's Class A and Class AB power amplifiers. Designed and made in Toulouse, it sold for EUR 5,880 in France. Its main difference from the CD140 and DAC140, which share its case, is an extension slot at the rear that accepts an optional phono or DAC drawer, so the preamplifier can grow with the system.

Key specs that matter

Out of the box there are five line inputs - one balanced on XLR and four on RCA - all with the same sensitivity and an input impedance above 10 kOhm. Outputs come as a stereo pair of XLR jacks plus a stereo pair of RCA jacks. The output impedance stays below 50 ohm, and the stated bandwidth is 20 Hz to 20 kHz. The DAC drawer adds two coaxial and two Toslink inputs, and the phono drawer adds an MM or MC input. Height is 100 mm, width 420 mm and depth 340 mm for the chassis alone, the weight is 7 kg, and the finish is mineral grey over an aluminium and steel body.

Engineering and use context

Gain comes from four double triodes, two ECC82 and two ECC83, arranged as a single Square Tube stage - four valves in one stage give the circuit its name. In the preamplifier a pair of transistors assists the valves to drive long output cables. Current through the output valves is fixed by reference voltages and kept well below their rating, which Kora says is meant to extend valve life, and the stage draws on two regulated rails, one positive and one negative. Volume runs on a scale from 00 to 80, which are position marks rather than dB values, and a mute key on the remote drops the level to 00 and restores it on a second press. Each input can take its own level offset so that sources of different output match at one volume, and the balance moves over plus or minus 10 steps. At start-up the display recalls the last input, volume, balance and offset. Fitting an extension means switching off, removing four screws from the slot cover, sliding the drawer onto its rails and screwing the plate back, after which the unit detects the module itself. On the phono drawer, MC loading and capacitance are chosen with switch blocks underneath.

Pairing

The balanced output suits the Kora TA240 or TA480 stereo power amplifiers and the CSA Class A models, while the RCA pair covers other power amplifiers. The CD140 and DAC140 plug into its line inputs, and the Kora Phono Stage can take one of the RCA or XLR positions when the phono drawer is not enough.

Alternatives

Kora currently lists no other line preamplifier, so the PR140 is the only model of the brand in this category.