Harman Kardon PM640VXi Ultrawideband Amp — 45 WPC, Made in Japan

A 45-watt amplifier built by a company that spent the 1980s arguing the watts were the wrong thing to look at.

Harman Kardon’s position was that music is made of transients, and what a transient asks of an amplifier is not sustained power but current, delivered instantly. They engineered for that and called it High Instantaneous Current Capability. The PM640VXi will deliver plus or minus eighteen amperes on demand. The practical result is an amplifier that sounds unbothered by speakers its power rating says it has no business driving, and it is why people who owned these in the eighties tend to speak about them the way they do.

Two things make that current available. The first is a power supply far larger than 45 watts per channel requires — the transformer accounts for a startling share of the weight. The second is the design philosophy around it: low negative feedback, and the ultrawideband response Harman Kardon built their reputation on — quoted here from half a hertz to 167 kilohertz. Wide-bandwidth designs of this era were chasing the phase behaviour inside the audible band, not the inaudible extremes themselves, and Harman Kardon were among the most committed to it.

The phono stage is fully discrete — no op-amps in the signal path — and it is the part of this amplifier people single out most often. If you are running a turntable, this is a considerably better front end than the phono sections fitted to most integrated amplifiers of the period.

The facilities are generous. Two pairs of speakers, switchable, and two tape decks with dubbing between them. Phono, tuner, video and both tape loops. Bass, treble and balance, with tone defeat to take the controls out of circuit entirely. Loudness contour, a subsonic filter, and a switch for stereo, mono or reversed stereo. Headphone socket on the front.

Built in Japan, and the VXi generation of 1987 and 1988 is the more powerful one — 45 watts per channel rather than the 35 of the earlier PM640, in a slightly larger chassis and with wider bandwidth. It is worth knowing the difference, because the two are routinely confused and the specifications get mixed up between them.

At roughly four inches tall and just over seventeen wide, it is a compact, low, unobtrusive component.

Condition is Very Good.

A few relevant specifications:

A compact Japanese-built integrated with a serious power supply, a discrete phono stage and far more current on tap than its rating suggests.

Available for pickup in Kanata, or shipped across Canada and internationally — we have sent equipment to fifteen countries in the past year, each piece packed in-house in 275 lb test double-wall boxes. Live shipping rates for your address are calculated at checkout. Backed by Radique Audio’s Bumper-to-Bumper Warranty and our Perpetual Trade-Back Program. Available for audition by appointment in Kanata.

Harman Kardon PM640VXi integrated amplifier Specifications

• Stereo integrated amplifier with High Instantaneous Current Capability, ±18 A
• Power output 45 watts per channel into 8 ohms
• Total harmonic distortion 0.09% into 8 ohms
• Frequency response 0.5 Hz to 167 kHz
• Damping factor 58
• Input sensitivity 2.2 mV (MM phono), 135 mV (line)
• Signal-to-noise ratio 80 dB (MM phono), 83.7 dB (line)
• Channel separation 58 dB (MM phono), 67 dB (line)
• Fully discrete phono stage
• Inputs: phono, tuner, video, tape 1 and tape 2 with dubbing
• Two switchable speaker pairs; front headphone socket
• Bass, treble, balance, tone defeat, loudness contour, subsonic filter
• Stereo / mono / reverse-stereo switching
• Made in Japan, 1987-88
• Dimensions: (Width x Height x Depth) 17.4 x 4.1 x 13.8 inches (443 x 103 x 351 mm)
• Weight: 12.1 lbs (5.5 kg)

⚠️ Important Information for International Buyers

This unit is configured for North American 110/120V power. Buyers outside North America will require a step-down transformer and appropriate plug adapter.

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Backed by Radique Audio’s Bumper-to-Bumper Warranty and our Perpetual Trade-Back Program. When you’re ready to move on, we’ll take it back. That’s the Radique difference.

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