Integrated amplifiers — Audio Note Jinro

The Jinro is an integrated amplifier with a single-ended valve circuit from Audio Note UK, the British company whose Level system grades its products by circuit and component quality. It is based on the 211 directly heated triode and uses the same circuit design and topology as the Ongaku. The difference lies in the wiring materials - the Ongaku uses silver wherever possible, including all transformer windings, while the Jinro uses copper.

Key specs that matter

One 211 per channel working in pure Class A gives about 20 W per channel into 4 or 8 ohms. The amplifier has four single-ended RCA line inputs, rated at 450 mV sensitivity and 100 kOhm input impedance. Rectification is handled by two 5R4WGB valves, and the input and driver stages use ECC82 or 5814A and 7044 or 5687 valves. Channel balance is within 0.3 dB. The mains input accepts 100 to 120 V or 220 to 240 V at 50 or 60 Hz, and power consumption is about 200 W. The chassis is 305 mm high, 305 mm wide and 640 mm deep, and it weighs about 38 kg, mostly because of its transformers.

Engineering and use context

The Jinro meets every Audio Note Level 3 criterion - Class A bias throughout, no global feedback, one output valve per channel, a valve rectifier, a directly heated triode and a defined grade of parts. The 211 is a large transmitting triode able to give more power than the 300B found in many single-ended amplifiers. In the output stage a single 211 handles both halves of each cycle, and the distortion this produces is mostly second order. The driver stage is coupled to the output stage through an interstage transformer made by Audio Note, wound in copper on a double C-core with HiB laminations at a 1 to 2 ratio, and the output and mains transformers use the same type of core. Resistors are Beyschlag parts chosen to Level 3 standards. The Jinro uses the same brand of 211 valves as the Ongaku, and Audio Note's own 211, the 4242E, can be fitted. Top plates come in natural or black anodised aluminium. Measured signal-to-noise ratio is about 44 to 62 dB unweighted.

Pairing

With modest power and no feedback, the amplifier needs sensitive loudspeakers with an easy load, ideally rated at 92 dB or more, such as Audio Note's own models. CD players, DACs and an outboard phono preamplifier connect to the four line inputs.

Alternatives

The Jinro circuit is derived from the Audio Note Ongaku, a 211 integrated amplifier with silver wiring.