Nakamichi AV-10

The Nakamichi AV-10 Audio/Video Home Theatre Receiver is one in a series of remote control amplifiers with Harmonic Time Alignment (HTA™), manufactured in Malaysia by the Nakamichi Corporation. This was a high specification amplifier that led the AV series. After buying one for sale on eBay and repairing it, I managed to review it, hence this multi-page article will be useful for anyone considering buying it in the pre-used markets.

Review

Although the AV-10 looks similar to the AV-8, it has some major differences in the specification. The AV-10 can provide 120-watts power output through the front channels in stereo mode, and 100-watts through all the channels in surround mode. In order to achieve these power output levels, the design incorporates two independent mains transformers to provide the energy reserves required by the amplifier circuitry. The "3-amp PCB", which has the surround channels, gets their power from one dedicated transformer through CN307, whilst the "L/R amp PCB" that has the front channels gets its power from the other transformer through CN302. With two extremely large transformers and one standby transformer, the AV-10 ends up with a mass of 16 kg.

The front channel transistors consist of 2SC5242 and 2SA1962 complementary pairs manufactured by the Toshiba Corporation. The same complementary set connected in parallel supports them, to provide 120-watts output. The 2SC4793 and 2SA1837 complementary pair drives the power output transistors in turn.

The 2SC5242 is a NPN silicon transistor with collector current (Ic) rating of 15 A suitable for 80 W applications, however in this design there are two in parallel to provide 120 W output. The 2SA1962 is its PNP complement, and there are two of these as well.

In the past, I have reviewed amplifiers that use the same power output transistors as this Nakamichi; however, there is something about this amplifier that makes it sound different and better. Perhaps the HTA technology that it employs is what makes it sound this way. With the red display, this huge beast of an amplifier has a menacing look about it. It certainly will shake the pillars of the church if you use one of these in the hall.

My amplifier friends in the UK will be excited to learn that the volume knob has a servo control motor that physically rotates it. If you use the remote control to adjust the volume level, you should see the volume knob physically rotate!

Price/eBay

The AV-10 amplifier was highly desirable and one of the few models with 100-watts output for the surround channels, and HTA technology. This home theatre system could be used in large halls and cinemas to produce that high-quality sound people like to hear. A new one in mint condition together with the box, manual, and remote control, would cost well over one thousand pounds, whilst a used one without remote and slight damage around five hundred pounds. A totally broken one would be approximately one hundred pounds as it is still useful for parts or modification projects. Before you rush off to eBay to see if there is one for sale, please continue reading the following pages of this multi-page article, which shows the inside engineering.

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