AVI Neutron

Paul White tries out these tiny, British‑built monitor speakers — and discovers that small really is beautiful.

AVI is a British audio systems components manufacturer regarded as something of a rising star in the hi‑fi world, and whose latest venture is into loudspeaker design. Their first product in this field is the tiny Neutron, measuring only 254 x 235 x 195mm. Hand‑finished in natural cherrywood veneer, the Neutron is a passive, ported, two‑way system using Vifa drivers; a 115mm inch bass/mid unit with a 25mm voice coil augmented by a 19mm soft‑dome tweeter.

I spoke to designer Martin Grindrod, who spent over three years researching the project. He explained that although he's adhered to conventional technology, the Neutron challenges the accepted wisdom of loudspeaker design in some key areas, particularly when it comes to taking accurate and meaningful measurements. He stresses the importance of proper cabinet damping to minimise the effect of internal reflections, and maintains that the computer‑based measuring systems often used in loudspeaker development produce meaningless results below 200Hz. Apparently, AVI has invested heavily in specialised test equipment, and has even constructed its own outdoor testing tower for making free‑field measurements.

The crossover point has been set at 10kHz, well away from the vulnerable speech band, and air‑cored inductors and metallised polypropylene capacitors are used in the fourth‑order crossover filter. A second‑order filter is used to drive the tweeter, and the overall response is flat within +/‑ 1.5dB up to 20kHz, with the bass roll‑off starting at 70Hz. Apparently the tweeter is rated up to 40kHz, with only a 6dB roll‑off at that frequency.

The bass/mid driver, which is recessed so as to be flush with the baffle, has a reassuringly large magnet, and a die‑cast chassis supporting a doped paper, curvilinear cone suspended in a soft surround. Connection to the speaker is via rear‑panel binding posts and the holes in the terminal are large enough to accept banana plugs or very heavy gauge cable. There is no provision for bi‑wiring, and the speakers are not magnetically shielded.

Listening Test

Appropriately, the speakers were driven from an AVI integrated amplifier which delivers up to 100 watts per channel, and the speaker stands placed close to a wall in accordance with the manufacturer's recommendations. These speakers, which have a nominal 8Ω impedance, are aimed primarily at the hi‑fi market, but because of their size and their design brief for accuracy, I was keen to see how well they would fare in a nearfield monitoring situation.

Accepting the lack of really deep bass, which is inherent in any design, the Neutrons managed to sound full and smooth, with no trace of boxiness. The choice of a high crossover point appears to have paid off, because the whole of the critical mid‑range is handled smoothly by the bass/mid driver, resulting in an open, detailed sound devoid of any harshness or nasty phase effects. These are very revealing speakers, partly because of their exceptional mid‑range and high frequency integrity, but also because the mid‑range isn't overwhelmed by bass, which is so often the case with full‑range monitoring systems.

Because the Neutrons aren't magnetically screened, I did some tests using my Apple 14‑inch colour monitor, and found that no problems occurred unless the speakers were brought closer than about ten inches from the sides of the monitor.

When it comes to the bottom line, these are quite expensive speakers given that you can buy a pair of JBL Control Ones for about half the price, but in their favour, I don't recall every having heard such an accurate or natural‑sounding small speaker. Used in the nearfield, the imaging and detail delivered by these speakers is beyond reproach, and there's no shortage of level either, providing you have at least 50 watts per channel to play with — the quoted efficiency is 83dB for 1 watt at 1 metre. If you need quality, but space is at a premium, these are most definitely speakers to check out.