Усилители для наушников — iBasso PB6 Macaw

The PB6 Macaw is a portable, fully balanced analogue headphone amplifier from iBasso with no DAC inside, so it needs an analogue signal from an external source. It can run in two amplification modes - one built around four JAN6418 subminiature vacuum tubes, the other a solid-state Class AB circuit - and it works either from its internal battery or from an external 12 V DC supply. The US price is USD 499. The aluminium housing has a dark glass top panel through which the glow of the valves stays visible, and hinged guards protect the controls.

Key specs that matter

Through the 4.4 mm balanced output the PB6 delivers 1,600 mW per channel into 32 ohm on battery and 2,300 mW per channel with the external supply connected, both at under 1% THD, with maximum levels of 8.5 Vrms and 9.5 Vrms. The 3.5 mm single-ended output gives 660 mW per channel into 32 ohm from either source. Output impedance is 1.2 ohm balanced and 0.5 ohm single-ended. In Class AB mode the balanced path measures -112 dB THD+N, 125 dB dynamic range, 135 dB crosstalk and a 2.3 microvolt noise floor, with a response of 10 Hz to 80 kHz within -0.1 dB. Tube mode reaches 15 Hz to 80 kHz within -0.5 dB, 116 dB dynamic range and 100 dB crosstalk. Gain is +6 or +12 dB in Class AB and +8 or +14 dB in tube mode. The case measures 140.7 x 78.9 x 19.6 mm and weighs 293 g.

Engineering and use context

In tube mode the four JAN6418 valves act as the gain stage and feed a buffer, while Class AB mode uses an op-amp plus buffer circuit with four BUF634A chips for current. The tube section runs from an anode supply of up to 22.5 V. Each valve is suspended in PORON damping material to curb microphonics and sits under a metal mesh shield against interference. An 8.4 V polymer battery pack replaces the usual 3.7 V cell, which cuts ripple from DC-DC conversion. Playtime is about 13.5 hours in Class AB and 9.5 hours in tube mode, and a full charge over USB-C takes about 2.5 hours. Volume runs through an NJW1195A four-channel control IC in 0.5 dB steps, and a separate switch selects high or low bandwidth.

Pairing

Inputs come in 3.5 mm single-ended and 4.4 mm balanced form, and feeding the single-ended input into the balanced output adds a further 6 dB of gain. The box includes a wall adapter, braided single-ended and balanced interconnects and a USB-C cable, and the DC input also accepts the charger of the iBasso DX340.

Alternatives

The iBasso PB5 Osprey is a portable balanced amplifier that uses two Nutube 6P1 valves and is rated at 1,700 mW per channel.