Интегральные усилители — Audio Note Cobra

The Cobra is an integrated amplifier from Audio Note (UK) and marks the company's entry into push-pull designs, combining a valve power stage and a built-in DAC section. It is produced in Lithuania at the Serva Se factory and supplied in a black finish only. Announced in 2019 for release the following year, it was planned in four versions, and the price at launch was about EUR 3,950.

Key specs that matter

Output is 28 W per channel in Class A push-pull, taken from two pairs of EL34 pentodes, one pair per channel. The full complement is four EL34, two 6AU6 and two 5670 valves. Three analogue stereo inputs use silver-plated RCA sockets, with an input sensitivity of 300 mV and an input impedance of 100 kohm. Channel balance is within 0.3 dB. The chassis measures 340 mm wide, 199 mm high and 451 mm deep including valves, knobs and connectors, and weighs 13.6 kg. Maximum power consumption is 175 W.

Engineering and use context

At the input, 6AU6 pentodes run in triode connection, while the 5670 double triodes form a cathode-coupled phase splitter that drives the output valves. Coupling between these two stages includes both low-frequency and high-frequency compensation networks. The output transformers are double C-core units on IHiB cores, made in-house to the company's own design, and the company states that they let the Cobra drive many different speakers. The power transformer, also an in-house design, uses heat-treated non-oriented silicon steel laminations. The high-voltage supply is built from silicon diodes in a voltage doubler arrangement and filtered by a choke of the company's own design. Three digital inputs feed the converter - coaxial up to 24-bit and 176.4 kHz, optical up to 24-bit and 96 kHz, and USB-B up to 16-bit and 48 kHz. Conversion is done by a Philips TDA1543 chip working natively at 16 bits without oversampling, so higher-resolution signals are truncated to that word length. A remote control handles volume, mute and input selection, and Audio Note covers the amplifier with a two-year warranty.

Pairing

The internal converter lets a CD transport, a streamer with a coaxial or optical output, or a computer over USB connect without a separate DAC, alongside up to three line-level analogue sources.

Alternatives

The Audio Note I Zero is a smaller integrated model in the Audio Note range, delivering 8 W per channel from four ECL82 valves.