Integrated Amplifiers

Design Centre Manager, Takashi Arai, is very clear about his concept of the 'perfect amplifier'. 'My goal is to make an amplifier with a high speaker driving force – I think that's all there is to it', he explains modestly. Takashi-san expands, 'For that purpose, the amplifier's output stage and power supply are critical, not only capable of supplying high levels of current but also clean and free of distortion and interference'.

In practice the PMA-A110 can trace its roots right back to the top-of-the-line S1 series from 1993. 'These were the first amplifiers to use UHC-MOS (Ultra High Current-MOS) devices – single FETs that could carry a large current. Initially we had to use industrial rather than audio semiconductors – my colleague spent six months alone in a dormitory in Kawasaki looking for high-capacity UHC-MOS devices and doing research on how we might use them for audio.'

The PMA-A110 employs 2SJ555/2SK3307 FETs, as used in the PMA-SX11 and '2500 amplifiers. 'Yes, but it's the driver stage for these power transistors that's been worked on most, derived from our work on the 'SX11. While the PMA-2500 used a three-stage circuit with resistors to set the operation point, the 'SX11 and 'A110 use a more elegant two-stage solution with the constant current source defined by diodes and transistors.

'I believe our pursuit of "Subtlety and Power" and Denon's new sound philosophy of "Vivid and Spacious" will carry us into the future.' PM