Интегральные усилители — Naim NAIT XS3

The NAIT XS 3 is the middle model of the Naim Audio integrated amplifier trio, placed between the NAIT 5si and the SUPERNAIT 3 and housed in the slim XS-series aluminium case. It went on sale on 31 July 2019 as the successor to the NAIT XS 2 of 2013, after a development cycle that Naim puts at six years, and the main changes were a reworked power amplifier section and the addition of a moving magnet phono stage. It has since left the current Naim catalogue.

Key specs that matter

Rated output is 70 W per channel into 8 ohm at 0.1 percent THD+N. Four line inputs labelled CD, Tuner, Stream and AV accept either RCA pairs or 5-pin DIN plugs, with an input impedance of 47 kohm and a sensitivity of 130 mV, and a fifth 5-pin DIN socket marked Aux also carries +24 V to power an external Naim phono unit. The internal MM input presents 47 kohm with 470 pF of capacitance and has gain matched to 5 mV cartridges. Outputs comprise two fixed-level DIN sockets for AV and Stream at 130 mV and 600 ohm, a variable RCA pair for a subwoofer and a variable DIN pre-out, both at 775 mV from under 50 ohm, plus a 6.35 mm headphone jack. Power draw is 140 W in normal use, 14 W on standby and below 0.3 W when switched off. The case is 432 mm wide, 70 mm high and 301 mm deep, and the amplifier weighs 8.5 kg.

Engineering and use context

In the power amplifier the engineers doubled the speed of the voltage gain stage, and new transistors in the second gain stage allowed the cascode arrangement to be dropped. According to Naim, removing the cascode means less stabilisation is needed, which doubles the slew rate and cuts group delay. The phono circuit is built in three stages - a gain stage, passive equalisation, then a final gain stage with active equalisation - and its RIAA capacitors and resistors are through-hole film parts chosen for low microphony. The bass end of the RIAA curve is a custom shape lying between the traditional and IEC versions. An Alps Blue Velvet potentiometer handles volume, reed relays switch the inputs, ceramic insulators sit under the power transistors, the microprocessor control section is galvanically isolated from the audio circuits, and the boards rest on mounts that reduce microphony. The headphone output runs in Class A. Control comes from the NARCOM-5 infrared handset using RC5 codes, with a 3.5 mm remote input jack on the rear.

Pairing

The variable sub output feeds an active subwoofer, and the DIN pre-out lets a separate Naim power amplifier be added later. Naim also states that the XS 3 can be upgraded with an external power supply.

Alternatives

The Naim SUPERNAIT 3 is the larger integrated in the same generation, rated at 80 W per channel into 8 ohm in a taller 87 mm case.