Прочие устройства — Keces Audio P9

The P9 is a dual-output linear power supply from Keces Audio, sold by the maker as the P9 9A Ultra Low Noise Linear Power Supply and by some European outlets as the P9 Dual. The 9A in its name reflects the combined continuous current of its two rails. It powers two DC-fed components from one chassis, and its regulation circuitry follows the discrete approach Keces uses in the P28 as well as the P14 and P6. The European price was EUR 899 including VAT.

Key specs that matter

Zone I is switchable between 5, 7, 9 and 12 V and supplies 4 A continuously with peaks to 5 A. Zone II covers 12, 15, 19 and 24 V and supplies 5 A continuously with peaks to 7 A. Keces specifies ripple noise below 220 microvolts at full power and below 150 microvolts at a 60 W load, and total residual ripple is given as under 1 mV RMS. Maximum draw from the wall is 330 W, and the mains input is set manually for 230 V or 115 V AC. The all-aluminium case measures 300 x 220 x 66 mm, and the unit weighs 6 kg net or 7 kg packed.

Engineering and use context

The toroidal transformer is wound in-house by Keces, then sealed in resin and isolated mechanically so that it limits vibration and stray magnetic fields. Integrated regulator chips are avoided - the P9 uses discrete parts only, with each stage regulated independently. The two outputs have separate grounds, which keeps one connected device from injecting noise into the other through a shared return path, and a dedicated ground terminal on the case allows further grounding options. The AC inlet module uses OCC silver wiring, and the board is made with 2 oz copper traces. The DC jacks are gold-plated to lower contact resistance. Keces states that the unit produces no hum or buzz at 50 Hz even at peak load. Protection covers over-temperature, overload and short circuit conditions.

Pairing

Because each zone has its own voltage selector, the P9 can feed two different components with different input requirements, one low-voltage device on Zone I and a higher-voltage device on Zone II. The box includes a mains cable and DC adapter leads that convert between 5.5/2.5 mm and 5.5/2.1 mm barrel plugs. Each connected component has to draw no more than the continuous current of the rail it sits on, with the higher peak values quoted as short-term limits only.

Alternatives

The Keces P28 is the linear supply in the same range whose discrete regulation design the P9 borrows.