NAD 310 Amplifier
Model 310 is the easiest and cheapest model in the range of amplifiers of this company, but it was the model that caused a real furore in the English audio press a few years ago, which experts considered it "the best buy" in this price category.
NAD audio equipment is addressed to those amateurs who prioritize the sound quality of their equipment and are ready to put up with the lack of any "extras" and functional "bells and whistles" if they do not directly serve the purpose of improving the sound quality. And we must say that the engineers of the firm are very successful in this, and today the high reputation of the NAD brand among audiophiles is not questioned by anyone.
In designing the 310, the company's engineers made an unprecedented effort to economise on literally everything in order to make the price of this model affordable to almost any fan of good sound on a modest budget. That explains the unusual design and circuitry features of this amplifier such as its single-ended power supply and the use of a combination of MOSFETs and bipolar transistors in the output stage of the power amplifier, connected in a pseudo-complementary circuit. Since the amplifier power supply is unipolar, it was necessary to connect the speakers to the amplifier output through high-capacity electrolytic isolation capacitors, which isolate the load (the speakers) by DC. In turn, to compensate for the influence of the electrolytic capacitor impedance on the output impedance, a special feedback circuit is introduced in the amplifier. Such, to put it bluntly, non-trivial circuitry.
As for the construction of the amplifier it can be noted that it is well made, like any British thing, but it has a very specific design, typical of all hi-fi components of NAD. Although this amplifier not only has no remote control, but also no amp to connect the turntable, it has two jacks (3.5mm "jack") to connect to a portable stereo recorder for recording and playback. (So it begs the analogy with the front AV input to connect a video camera in TVs and VCRs).
However, it is time to test our Englishman. First, let's offer him to try his hand at working with floor-standing speakers. The sound of the amplifier turned out to be amazingly melodic and musical with good tonal balance. With the off timbre NAD sounded very detailed, the bass was clear and firm. However, on some pieces of music we felt a slight slight lack of the lowest frequencies (obviously, the presence of an electrolytic capacitor in the signal path). The stereo panorama was transmitted very well, even the atmosphere of the recording studio was felt. When I turned on the timbres the sound improved a little bit more, but only a little. We were surprised that there was so little lift in the frequency response at the edges of the range when the tone controls were fully engaged. However, since the NAD sound is well balanced at all volume levels, this decision seems to be justified: deep correction in the timbrel inevitably leads to additional phase distortion in the amplified audio signal.
When switching to a "shelf" speaker NAD sound became less expressive and not so voluminous. However, now setting the timbres to "5 o'clock" led to a very noticeable improvement in sound quality, which came close to the sound with a floor speaker.
But, again, these nuances of sound were barely noticeable, and in both cases NAD sounded "excellent", so we easily awarded it "5" for sound quality. After getting a closer look at this wonderful amplifier, we were able to appreciate the audiophile nature of its sound and see if our English colleagues, who have devoted to it in their time rave reviews in the British audio press, were right.
