Acoustic Energy AE22

Photo: Mike Cameron

Like the venerable Yamaha NS10, this nearfield design puts accurate time-domain response at centre stage - but what does that mean for your mixes?

The British loudspeaker manufacturer Acoustic Energy was set up initially in West London 1987, but relocated in 1995 to a large facility in the Cotswolds (now a popular area for loudspeaker manufacturers, with both ATC and AVI not that far away). The compact AE1 model was the design that built the company's reputation when it was launched in 1988 — and although it was originally designed for the professional market, it quickly became a hi-fi favourite too, winning many awards.

In recent years Acoustic Energy have concentrated mainly on the volume-orientated entry-level and mid-range hi-fi and multi-channel home-theatre markets, but have recently made a significant move back into the serious professional market with their latest model, the AE22.

Apparently, it has been 15 years since the last professional AE speaker (the AE2) —and the world has moved on somewhat since then. So this new design (from the drawing table of designer Phil Ward, who has contributed often to the pages of this magazine over the years, and to the SOS Forum more recently) has been created to provide a highly accurate recording monitor to take over from classic designs like the Yamaha NS10. Available in both passive and active versions, the AE22 is designed to be used on a mixing desk's meter bridge (or similar surface), placed at ear level, for nearfield monitoring.

Overview

The distinctive-looking AE22 is an attractive monitor, with the tweeter offset from the woofer and protruding slightly from the top of the cabinet. There's no protective grille over the drive units, and their physical arrangement means that the speakers are supplied in left and right handed pairs. The cabinet is a sealed-box design (like the NS10), and measures 35cm wide, 25cm high and 30cm deep. The passive version weighs 10kg, while the active design — which I looked at for this review — is 5kg heavier and 30mm deeper (to house the amplifier chassis).

Both versions of the AE22 feature the same drivers and performance specifications, including the quoted frequency response of 60Hz to 40kHz ±3dB. The tweeter is a proprietary version of Vifa's distinctive 25mm dual-concentric diaphragm with a waveguide centre-plug. AE describe it as a 'ring radiator' and it provides a frequency response that extends well above 20kHz, with very low distortion. A third-order Bessel crossover splits the tweeter and woofer signals at 2kHz.

The bass driver is a 200mm unit with a die-cast aluminium chassis and a large 'underhung' voice coil. The latter means that the magnetic gap in the motor assembly is much larger than the voice coil, so that the coil always remains within the magnetic field during the cone excursions. This arrangement provides a very linear motive force, with very low distortion. (Most speakers employ an overhung coil in which only part of the coil sits within the magnetic gap.) Confusingly, the manual states that the voice coil is 50mm in diameter, but the web site suggests 75mm — and the former is actually the accurate figure.

The cone itself is made of pressed anodised aluminium, which is extremely stiff, and also acts as an effective heat sink for the motor assembly. The central dust-cap is paper and provides some damping of the inner portion of the cone, while the heavy rubber surround keeps the outer part of the cone reasonably in check. Neither driver is magnetically compensated (shielded), so you need to keep the AE22s away from CRT monitors and moving-coil meters.

The passive AE22 has a slightly low sensitivity, at 97dB per Watt at one metre, and so needs a reasonably powerful amplifier. However, it provides a fairly easy 8Ω load to drive, and can cope with 200W peaks without strain. The rear panel carries standard 4mm binding posts and a Neutrik Speakon connector, wired in parallel.

The active version contains two power amplifiers and a line-level crossover (but to essentially the same design as the passive version), with some equalisation options included. The bass amplifier provides 150W RMS, while the treble amp provides 60W RMS. On the rear panel is a large heat sink, with an IEC mains inlet, power switch and integral fuse on the right-hand side, while four three-way rotary switches on the left determine the equalisation and input sensitivity. Operating voltage is fixed at 230V.

A combi-jack socket accepts a balanced line-level input via the XLR, or an unbalanced input via the quarter-inch jack socket. The input sensitivity is such that full output power is achieved with an input of 0.9V RMS (+1.3dBu). The rear-panel switch can increase or reduce this by 3dB, but even so this is an unusually sensitive input and you may find that you need in-line attenuators to cope if your desk or monitoring system has high output levels.

The equalisation facilities are controlled by the three-way rotary switches mentioned earlier. The LF (low frequency) switch provides a flat mode, a bass-cut option (-3dB from 70Hz) and an extended bass mode (+3dB at 40Hz). The cut mode is intended to simulate the characteristics of smaller loudspeakers, while the extended mode helps to bolster the LF performance — but at the inevitable expense of less LF headroom and a lower overall maximum output level.

A sealed-cabinet loudspeaker has a gentle roll-off of 12dB per octave, which tends to start higher than an equivalently sized reflex (ported) cabinet design. However, the latter rolls off at a much steeper rate of 24dB per octave, so although it will produce a higher level of bass down to the port frequency, below that it falls away much more quickly. In comparison, the sealed-box design continues to deliver useful signal to a much lower frequency — and without the ringing and time-smearing that a resonant port design introduces.

To the left of the heat sink, four three-way rotary switches are used to set equalisation and input sensitivity. Photo: Mike CameronThe mid-range section provides ±2dB of boost or cut at 400Hz and the high-frequency (HF) section provides ±1.5dB of shelving from 2kHz. The current switch positions are displayed on the front panel in a 14-LED array adjacent to the woofer. The first column shows the LF switch settings (up, flat and down), then the MF and HF settings, followed by the input sensitivity and, finally, the internal amplifier clip-warning indicators. The LEDs are not so bright as to distract or annoy, but they do make it very obvious when the monitors are powered up.

Auditioning

I first placed the active AE22s on stands set well out into the room and away from walls, to make an initial comparison with my usual reference monitors. Not surprisingly, in this situation they sounded quite bright and forward, but they were also surprisingly clean, demonstrating very fast transients and an impressive stereo image breadth. The rear-panel switches allowed the forwardness to be tamed quite reasonably, and the LF Extend mode certainly did bolster the bottom end quite usefully. As I mentioned above, like all sealed-cabinet designs the AE22's low-frequency response actually goes down a very long way, but the level tails off progressively. The AE22's equalisation compensates for this in the bottom two octaves. Provided you don't need excessive monitoring levels, this makes the system sound rather bigger than it has any right to!

When I moved the speakers to something more closely resembling their intended mounting positions above a console, the forwardness was far less obvious and I found that the flat EQ positions worked well. One of the greatest strengths of the AE22 (again, like all sealed-cabinet speakers) is the lack of bass overhang, and I know a lot of effort has gone into ensuring this monitor has an almost perfect time-domain response. Kick drums certainly start and stop very precisely (or at least, you can be confident that the ringing is the drum and not the monitor!) and that makes it very easy to hear the difference between — and therefore to accurately balance — kick drums and bass guitar notes. The bottom end of the mix doesn't become muddy and confused, as it could if delayed energy was being contributed by port resonances, and it all sounds very natural to my ears. OK, so you don't have the high-energy kick-drum boom from these monitors that you usually find with comparably-sized ported designs, but I don't think that's a bad thing when you are mixing or listening critically. An accurate time-domain response is arguably more important than a flat bass response. While these monitors might not gain favour in drum & bass circles (although they should) simply because they don't move enough air, as a mixing tool they are very impressive.

The critical mid-range is very clear as well, possibly because of the bass unit's very low levels of distortion. In most moderately priced speaker systems the bass driver normally contributes a significant amount of second- and third-harmonic distortion, and that inherently masks the wanted signals in the same part of the spectrum. This isn't the case with the AE22, which is surprisingly revealing — to the extent that mixes are exposed in all their glory — again, in much the same way as the classic NS10. Mixes made using the AE22s also seemed to remain very consistent when played back on a variety of different systems — ported nearfields, big PMCs, car systems, a cheap kitchen stereo and even iPods.

The stereo imaging wasn't quite as open and deep when the speakers were mounted above the console (almost certainly thanks to local reflections) but it was still impressive and stable. I tried the monitors both ways around — with the tweeters on the inside and outside — and found that the best imaging was with the tweeters on the outside, which the manual suggests is the best solution if the monitors are placed above the listening axis. If the speakers are below the listening axis, it recommends placing the tweeters on the insides of the pair.

Something else noted in the manual is that these speakers don't need to be aimed directly at the listening position in the way that most do. Not surprisingly, listening on-axis provided a noticeably brighter sound; I definitely preferred the slightly softer, more natural balance achieved with the speakers pointing almost directly straight down the room. Some experimentation is required here because there is a trade-off between spectral balance and stereo imaging, but once the speaker positions had been optimised, the results were very pleasing.

The AE22s aren't boasting the flattest frequency response on the block, but the tolerances aren't bad and the off-axis sound shows a smooth HF roll-off, meaning that the reflected sound within a room isn't as coloured as it can be with some monitors. In practice, I found that these speakers were quite tolerant of room treatment, and they worked pretty well even in a bright and untreated room.

Every time I used the AE22s I was reminded of the NS10s, in that the mid-range voicing is very similar, as is the speed and clarity of the bass end. However, the AE22s are more revealing and slightly easier on the ear, and you can get them to go significantly louder without fear of them blowing out those lovely smoke rings that mean another pair of £50 Yamaha tweeters!

These are attractive, solidly built nearfield monitors that update the NS10 concept very well, retaining the critical time-domain accuracy but with enhanced power handling and a better overall frequency response. Both the passive and active versions are something of a bargain for those who can appreciate the monitoring precision on offer here.