Naim Audio NAP 500 DR

Naim Audio NAP 500 DR

• 140W per channel output into 8 ohms; capable of prolonged output into 2 ohms with no discernible impact on performance
• Bridged power amplifier configuration for maximised open and closed-loop speed, with ten stages of local regulation per channel
• Two-box configuration with 500 PS power supply for optimum rejection of electromagnetic interference
• 1,100VA toroidal transformer provides 12 raw DC supplies for the power amplifier
• 25kg brushed, black-anodised chassis with distinctive heatsink plus variable speed intelligent fan system for discreet extra cooling if required

To avoid the compromises implied by the use of multiple sets of output devices, either in totem-pole or parallel configuration, the search was on for a very special output transistor. A bipolar transistor with a specific combination of very high current, power rating and bandwidth was needed, far in excess of anything available to Naim before. A suitable output device was eventually developed after six years' collaboration with a semiconductor manufacturer.

From an early stage of conception it was decided to use bridged amplifiers for each channel of the NAP 500. This allowed the design to have maximised open and closed loop speed, less intrusive protection circuitry and reduced interaction between input and output signals as the very high drive currents to the loudspeaker do not flow through the system earth.

Naim has always understood the importance of reducing supply-induced intermodulation distortions and mains harmonic electrical noise from an amplifier, and has always used regulated supplies in its premier amplifiers. It was considered likely that improvements in these areas would yield further large gains in performance. Each channel of the NAP 500 includes ten stages of local regulation. To reduce interference from the mains supply further, the transformer and first stages of the power supply are in a separate enclosure (the same size as a SuperCap), which provides twelve raw D.C. supplies for the power amplifier. Hence, the NAP 500 system consists of two boxes, a stereo amplifier and a separate power supply.

All new circuit topology has been developed to maximise bandwidth and reduce distortions and power supply dependency. Also, special attention has been paid to reducing thermally-induced noise, an especially important consideration in power amplifiers. A variable speed intelligent fan system provides discreet extra cooling if needed.

The performance of the finished amplifier exceeds the design brief in all areas. Power output per channel is over 140W into 8 ohms and compared with the NAP 135, which in itself already provided exemplary measurements, the NAP 500 has five times the internal bandwidth, a quarter of the distortion and a one hundred times reduced operating noise floor.

DR-Technology

The NAP 500 now features the new NA009 transistors first introduced in Statement. In development for over a year, this key component was created in partnership with a specialist semi-conductor manufacturer to achieve the best possible sound quality. The 300 also includes the high power Naim DR (Discrete Regulator) technology used in Statement to provide the smooth, stable power supply we know is critical for the audio electronics to make music come to life.

These two new technologies, combined with other small improvements to layout and componentry, mean the NAP 300 DR can produce even more of the fundamental musical pace, rhythm and timing that made the originals so popular with music lovers.