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31 Secrets

SOLO REVIEW
Avantgarde Acoustic Solo

A two-way active system that retains much of the character of Avantgarde's classic big horns

Martin Colloms, October 2002
HiFi News, Great Britain
When news emerged of a compact two-way hornspeaker from Avantgarde, I couldn't imagine what it could be. Unlikely as it seemed, this device was to be capable of wall or stand mounting, was full frequency range, and with its own, onboard control unit as well as a substantial power amp. And then the pics arrived, showing a barrel-shaped device, with 12in concentric double horn located at the business end. Interesting!

On delivery, the speakers proved larger than I'd expected and they looked a bit precarious perched on their fancy brushed alloy-and-plate-glass stands: in fact, optional stronger stands are planned for the near future. But everything fitted together well and the Solo proved to be easy to set up and drive.

Still offering the company's characteristic horn technology despite its reasonably compact dimensions, the Solo is intended to provide lusty peak sound levels in larger spaces such as a loft apartment. In can indeed be wall-mounted, using an accessory bracket which is capable of supporting the speaker's significant 30kg weight, and allows the speaker to be angled to the seating area.

While stereo is a given application, Avantgardes also presented the Solo as a five-channel home theater setup. Concentric speakers are, in any case, very well suited to centre-channel dialogue application, providing consistent spectral balance over the listening area. The Solo is also distinguished by an optional +4dB treble boost setting for - guess what? This is judged to be the right correction when used behind a perforated 'acoustically transparent' projection screen.

Add a subwoofer or two (yes, there are two options) and you would have one of the most dynamic and powerful domestic home theatre systems on the planet. Each single speaker is about £1600, so a 5.1 setup would be about £9000, but remember no power amps or costly speaker cabling are required.

The full-size rear panel is in cast alloy, carrying heat sinks for the built-in 250W power amplifier plus facilities and controls for the electronics. In addition to a subtle low frequency control, there is also a tunable 'high pass' or bass cut filter to marry it to a sub. Without the need to filter in the sub, the power handling of the Solo is beneficially enhanced without further intervention or loss of signal quality.

Three switched treble settings are present: The '+4dB"', 'bright for behind the screen; '-3dB' for bright, sparsely furnished rooms; and '0'. I found '0' just right with a '3/4' setting for the bass equalizer under free space, stand-mount conditions. Balanced and adapted singe-ended inputs are possible. There are independent volume controls and a ground lift switch to sort out hum problems. The unit can be run without an earth line thus is double insulated.

The power switch has two modes: On, and Relayed Energized via the 12V trigger remote link, standard for integrated control systems. The Solo may be driven straight form a volume-equipped CD player, from a preamp, from an integrated amp or even power amplifier, the latter using a suitable attenuator cable (see your dealer!).
At its heart is a 300mm chassis, flared pulp-cone bass mid-driver. Offering high sensitivity and low 'Q', it's barely loaded by a short (70mm) concentric horn, while low frequency loading is bass-reflex via four rectangular vents in the rear casting. The bass/mid driver is equalized to a natural response with the aid of a powerful onboard amplifier. Simple, 6dB/octave crossover divide the range to the treble horn, with its 100mm exit diameter fed by 25mm dome unit. This assembly mounts on the bass driver centre pole, the latter built with a generous 100mm high power voice coil. Finish is to the usual excellent Avantgarde standard with lacquered horn components and Nextel matte elsewhere, A variety of colours is available.

I found the sound disconcerting at first. This is quite a large speaker to stand mount and stands seemed too small for it, so to promote stability on my carpet I slid two small cone-type spikes under the base plate to add improved coupling to the floor itself. This gave some improvement in bass definition and mid clarity, and I note that a heavier-duty stand will soon be available instead of the elegant toughened glass type.

If you're familiar with the much larger Avantgarde speakers, you'll spot immediate similarities and difference when you look at the Solo. The Solo is more direct radiator than horn; in contrast to the almost fullrange horn configurations of the larger systems. Here, the main effective horn section for it is in the treble, yet both drivers have the characteristic Avantgarde quality - an articulate, crisp and almost tactile midrange, well projected and almost too 'live' sounding.
The Listening System

Classe CD-65 and Conrad-Johnson ART pre-amps were used, with a Marantz CD-7 player. Transparent SL was the unbalanced signal cable; for balanced connections I used van den Hul The Second pure carbon
This 'out of the box', exuberant nature grabs your attention and yet doesn't get in the way of music making. In fact, it makes many other speaker designs sound rather pedestrian.

Listeners seeking a smooth, even sound of high neutrality won't be happy with the Solo as it significantly alters the character of natural sounds (although in my opinion, not so much as to knock the overall performance off-balance). The ingredients are not those of a broadcast monitor, but are nevertheless chosen and blended to reproduce the performance qualities of music: life, energy, tempo and dynamics. They do these well, involving the listener. I can also see that a pack of five of these speakers could provide an extraordinary punch in a home theatre installation, remembering that the coaxial design is optimal for centre-channel duty.
I was also impressed by the sheer functionality of the Solo. For example, Avantgarde suggests basic settings of the many controls, while the versatile control range allowed for tuning the overall tonal balance to suit the speaker location in the room. In a free space position, good punchy bass was obtained with quite good extension for the size, to about 38Hz. Near the wall, some reduction in low frequency was easily set to restore the balance. That sturdy wall bracket accessory seems viable after all!

Further attributes include a good level of detail, satisfactory coloration and good overall tonal balance. Avantgarde's designers really know their business! That characteristic, almost zippy liveliness was present through the treble, with fine dynamic resolution coupled with some horn 'talk' in the low treble and mild 'grain' in the highest reaches.
While some moderate cavity- and cone-type colorations were present in the midrange, the clarity and sense of commitment was clear enough. This speaker was never boring. The decent sized bass-mid driver thrived on the direct coupling to the onboard power amplifier. The bass was punchier and more tuneful than we had any right to expect. From this drum-like enclosure. At less than 10ft (3m) listening distance the image focus was just average and fairly critical of position, improving at longer range. Timing per se was unexceptional, but the feeling of rhythm and involvement was good.
The bass equalization wasn't that strong and while the Solo is full range in its own right, the onboard filter facility allowed for easy expansion with a good sub to help create s till more powerful and dynamically capable system. As it is, it could easily play loud even in large 25 x 35ft listening room.

Avantgarde's high quality sound engineering demands respect and is continued with the Solo. This is a remarkable loudspeaker and defies a convenient pigeonhole. If the looks and format appeal, then choose your colour and enjoy the vibrant go-for-it sound which it can provide. It may look quite small in big speaker company, but the lcose-coupled amplifier helps deliver a solid, crisp bass. However, in home theatre installations it should be stunning - this for five channels, never mind seven! Noting that the Solo includes onboard amplification, automated power-up and great versatility, this fascinating speaker may not have universal appeal, but easily scores high enough for recommendation.
Lab Report
Despite their compactness, these speakers throw a punch. Maximum in-room sound levels of 114dBA were possible - massive! In a 5.1 or 7.1 combination they would be enough for a small cinema holding up to 100 persons.

Given room conditions, I measured a wide +/-3dB frequency response from 48Hz to 20kHz [Fig.1]. In practice, the room bass extended to 35Hz or so from a semi-anechoic -6dB point at -42Hz. So matching a sub woofer is really easy, when required. The concentric array gives wholly symmetric sound radiation and the off-axis results were good [Fig.2].

Measured exactly on axis, there was some unevenness, typically +/- 7.5dB in the treble, unweighted, and it sounded and measured somewhat smoother if tilted away a bit. Considered generally well balanced, the off-axis responses [Fig.2] were tidy out to 30 degrees, while at 45 degrees there was a dip as the upper midrange petered out - no real problem, this. Moving on to the spatially average din-room response, the result was pretty good, measuring +/-4dB 33Hz to 14kHz despite the usual floor reflection for the stand-mount location. Mid and treble were skillfully integrated here [Fig].

The bass ports had a significant secondary output at 380Hz [probably the mean diameter of the box] reading 18dB down. The main output was a t53Hz and the system was essentially equalized to maximally flat.

The low frequency graph [Fig.4], showing the adjustments, carries at its centre the free space reference equalized condition (note that the speaker's actual bass limit is about 40Hz, the vertical dashed line). Full bass lift does little for the '3/4' free space position. The response with shelved bass cut was for the wall-mount equalization, about -3dB at 100Hz, a fair approximation. The two filter rolloff responses show the bass limit filtering to use with a sub, a '60Hz' setting actually reads -3dB at 35Hz and '120Hz' measures -3dB at 80Hz. Experimentation with the system settings in a given room will usually help sort these matters out.