Naim Audio amplification
[1][2] The company has a sui generis approach to audio design, ignoring specifications and power ratings as indicators of the quality of an amplifier.
[12] Vereker attempted to reduce information loss at the design stage, by unconventionally disregarding test-bench measurements of harmonic distortion performance and output into a static resistive load.
[12] Naim says that to achieve amplifiers with low harmonic distortion, low noise, wide power-bandwidth, and constant dynamic output impedance, they pay attention to balancing dynamic impedance, open-loop bandwidth, slew rate, and propagation delay; the amplifiers are not subject to slew-rate limitation between 5 Hz and 50 kHz.
[18] In practice, modern products' bandwidth has been much extended, but the pre- and power-amplifiers are of such a tight operational fit and sonic synergy that they are rarely used with other makes.
[1][7] Naim strongly believes that an ample source of power is of the greatest importance, and the availability of external PSUs to accompany its products also reflects the philosophy.
[8] Vereker also believed that a well-designed amplifier must be stable at all times when driving real-life loads, which are different from those achieved in lab conditions because loudspeakers' impedances vary with frequency.
The design decision was made to use a suitable length of speaker cable (a minimum of 3.5m, with 5m being optimal) to provide the effective inductance.
Subtle mechanical and electronic changes introduced in lower-rung products — as a result of research at the flagship product level — have contributed to build and sound quality: control of internal heat dissipation, wiring, radio-frequency interference and mechanical vibration through more efficient materials, compliant mounting and decoupling.
[22][23] Naim have found that, with increasing amounts of digital circuitry in their boxes, the electronics are much more susceptible to microphony and other mechanical vibration.
[19] In terms of styling, the amplifiers up until 1989 are constructed of heavy aluminium extruded cases that act as heat sinks;[13] these were painted black with a metallic silver brim – thus nicknamed "chrome bumper" range.
[23] Reviewers of early Naim amplifiers criticised the distinctly "cottagey" styling, yet recognised that the money was spent on "what lies within".
"[14] In 2009, veteran hi-fi critic Malcolm Stewart noted that the communicative sound and minimalist design have been enduring characteristics of the entire range of Naim amplifiers since the inception of the firm.
Naim assembly staff build each piece of equipment in individual workstations from basic components and sub-assemblies, wire the product mostly by hand and progressively test to ensure compliance.
[35] Naim's own NAC A5 speaker wire occasionally comes in for criticism for its physical stiffness,[1][36][37] and also for imparting a "brittle, scratch" quality to the sound.
[38] Julian Vereker saw that there was room within hi-fi circles for subjective preferences, but he held that it was "totally wrong" to put presentation (i.e. soundstage, detail, and depth and imagery) ahead of content.
[11] And while Naim does not set out to achieve imaging and soundstaging as design goals,[40] reviewers have noted that some of the equipment is capable of delivering on these.
[9][42] In early product manuals, recognising that good results required high current amplification, Linn recommended using the Isobarik PMS tri-amped with Naim amplifiers.
[46] Early on, three NAP 250 amplifiers, fed by a 3-way NAXO electronic crossover, would typically be used, one for each stereo pair of the doubled-up treble, midrange and bass driver units.
In the late 1990s, still under Vereker's guidance, Naim developed a new flagship power amplifier using computer simulation and the latest transistor technology.
Search for a transistor with the desired sonic characteristics led Naim to Semelab, who had created a device working at a combination of higher current and lower operating voltage.
The output devices chosen, rated at 350W–70amp, are used singly within the amplifiers well within safe operating parameters; the use of protection relays, detrimental to sound quality, is thereby avoided.
However, having the power supply in the same case was found detrimental to the sound quality, so the PSU is located in a separate alloy enclosure, linked to the amplifier by sturdy cables with locking connectors.
The pre-amplifiers are designed to accept signals from source components without overloading, and Naim claims total stability and a very wide open-loop bandwidth.
[34] This is done so that the sensitive pre-amps, running at extremely very low voltages and currents, are not adversely affected by the hum field induced by the power supply.
Power supplies are connected to the preamps and amplifiers with a "SNAIC" – Super Naim Audio Interconnect Cable – terminated at both ends with DIN plugs.
""Also it is extremely wasteful of resources making class A power amps, since they use large amounts of electricity even when they are not playing music, [and] this means the waste heat has to be dissipated into the atmosphere without overheating the components and thus shortening their lives, which implies large heatsinks, big heavy and expensive in terms of resources pieces of equipment.
