The drivers are mated through a second-order passive crossover, although unusually, the tweeter is kept in phase with the bass/mid drivers for a phase coherent output. The ribbon extends down to a low crossover point of 2kHz, again echoing an increasingly common current trend amongst high-end speaker designs. The crossover itself is housed in a separate, milled out block of aircraft grade aluminium spaced from the bottom of the cabinet proper. Components are supplied by Tritec (air-cored inductors) and Mundorf (foil in oil capacitors, but employing Siltech/Crystal’s proprietary silver/gold alloy as a conductor) and hard wired with Crystal’s top of the line Dreamline speaker cable, which also extends up to the drivers.
Running-in loudspeakers is one of those topics that gets a lot of loudspeaker designers hot under the collar – one way or another. Thee are those who swear by it, and those who dismiss it out of hand. So who is right? Well, it could be both sides of the argument as the actual running-in mechanism is poorly understood (if at all) and varies significantly from one design to another, depending on the constituent parts and materials. So, on the one hand both Avalon and Focal are assiduous in running their speakers before delivering them to reviewers, whilst other manufacturers are happy to present brand new units.
The Arabesques arrived with around 12 hours of running time – and sounded nothing like the examples I’ve heard at shows. Whether that’s down to the drivers themselves (there’s some suggestion that spider condition is critical to cone driver performance) the crossover components or the wiring, who can say, but clearly these speakers were going to need a lot of running. I left them playing at serious levels around the clock, using a mixture of dense and dynamic musical material and a purpose designed burn-in track, but it was a full six days before they really started to open up and allow music to breathe in the way that previous experience suggested they could. Another two days and they really started to sing, at which point it was high time to reassess their positioning and set-up.
Of course, the company had installed and tweaked the position of the speakers in their original form. Breathing more freely, they demanded revisions to rear wall spacing, an increase in toe-in and a reduction in the distance between them. It’s this that makes burn-in such an insidious effect, because even though your speakers will get there in the end, the benefits that accrue could easily be undermined if you fail to revise and optimise their positioning. The very nature of the Arabesque and the manner in which its sound evolves makes the lesson especially stark.
On the recessed, rear face of the crossover block, contained within the curve of the speaker’s footprint, you’ll find the terminals, as well as a pair of level switches for the drivers. There’s a single pair of WBT binding posts that will take 4mm plugs or spades, whilst the two switches allow you to adjust tweeter level in three, 3dB steps and also cut bass output if room boundaries and acoustics demand it. But in some respects, the most interesting feature is found between the WBTs: a sub-miniature four-pin screw socket allows owners to directly connect Crystal’s own speaker cables whilst dispensing with the normal single or bi-wire tails. That has to be the ultimate in low-mass connection…
One other aspect of the Arabesque is deceptive. On paper at least, the sensitivity suggests that this should be an easy speaker to drive – and in some respects it is. However, two other sets of figures give rise for concern. The wide bandwidth (27Hz to 100kHz ±3dB) coupled with a ‘nominal’ 4 Ohm load suggest that things could get tricky for smaller amps. In fact, the minimum impedance dips to a 2.8 Ohms minimum and it’s no surprise to discover that when it comes to lower powered amplifier options, its push-pull valve amps that seem to do the best job, with their greater control at frequency extremes than their triode brethren and the considerable shelter afforded their output stages by the large lump of iron sat between them and the speaker load. Certainly, the VAS Citation Sound mono-blocs did a sterling job, even if they didn’t grip the speakers the way bigger amps did. On the solid-state front, I think around 100 Watts should be considered a sensible minimum, otherwise you’ll risk seriously underselling the speakers’ capabilities. That impedance dip also means that the speaker cables are under stress, with a noticeable benefit to be had from doubling up – or shotgunning – the speaker wires. Engaging the Bass Cut results in a rather kinder 4 Ohm load, but I’m not sure it’s sensible to consider this as an amplifier matching solution, the trade off in bass output being a poor exchange.