OLDE WORLDE It was worth it. The exceptionally light cabinet was also particularly rigid and free from colouration. To provide suitable damping, the cabinet was filled with layers of varied densities of foam. The original Kobex woofer and copper tweeter made it across from the SL6 but, in this case, they were hand selected. The hardwired crossover was matched to a specific tweeter, thus ensuring correct alignment with the 21kHz compensation network. Like the SL6, the first SL600s used simple 4mm speaker sockets – making banana plugs essential. Unlike the SL6, the SL600 came without a grill. This was because the cabinet would lose rigidity if drilled further for grill mounting points. Yet, with its smart Nextel paintwork and diecast metal faceplates, few customers would want to cover the SL600. Let’s not forget, this was seriously hi-tech stuff in 1984! Celestion obviously received complaints about its lack of grill, as the next version, the SL600Si featured one (cleverly attached to the existing faceplate bolts). Skipping the ‘S’ improvements altogether, it was only in 1988 when the SL600 got its first upgrade. Like the SL6, the new Si included a revised crossover with biwiring and some cosmetic tidying including a new, harder wearing, paint. Interestingly, the SL600 never got the aluminium tweeter or the dual density woofer surround (they were destined for the even posher SL700) but perhaps this was no bad thing as it meant that, for better or worse, the SL600 never lost its original character.
SOUND QUALITY Celestion SL600s divided audiophile opinion like few other loudspeakers ever made. Detractors criticised the ‘sat upon’ sound, slow bass and tragic efficiency, whereas supporters loved their eerie transparency. Taking the nay-sayers first, there is no doubt that the SL600s are woefully inefficient - 82dB rules them out for use with many amplifiers. In addition to this, they also tend to be system and room fussy. They require plenty of space from a rear wall and, believe it or not, decent room temperature – that PVC woofer surround moves very little when it gets cold! Against modern speakers, bass can also justifiably labelled as ‘off the pace” or ‘turgid’. Yet, just before you write them off, take a closer listen... When properly set up and matched with sympathetic ancillaries, the SL600s produce a wonderfully holographic soundstage that can rival a Quad electrostatic for transparency.
Furthermore, there’s a seamless flow from bass to treble that, even today, is impressive in its even-handedness. That copper tweeter may have been inefficient, but it suffered none of the gritty and spiky characteristics that many later aluminium domes suffered from. Instead, it provided good detail and, crucially, a level of upper mid that enabled it to blend with the woofer. Precise, subtle, seamless and transparent: the SL600 was, and perhaps more remarkably still is, all of these. Differences between the standard and Si model are slight. The treble has perhaps a touch more detail, but there’s not a lot in it. If you’re in the fortunate position to bi-amp however, then the biwiring terminals of the Si make it a musthave option. Incidentally, either pair benefit from a pair of heavy 20-24” high stands. Whatever you do, though, don’t use top spikes, as these pierce the delicate cabinets! As with most speakers, tweaking brings out some benefits in sound. Probably the greatest difference can be made by simply changing the internal ‘speaker cable. The standard cable is not the best, and a decent modern cable really opens the sound up. If you do take this course, do watch the tweeter, though. The solder connection to it is fiddly and a mistake could damage the unit. Personally I’d leave the crossover and internal damping foam well alone. However, if you don’t mind the odd looks, then removing the bass faceplate is an easy way of improving the imaging. Whilst you’re there, don’t forget to tighten up the woofer’s bolts. Like any speaker, these work
SECOND THOUGHTS As eighties as red braces, Golf GTis and Filofaxes, the SL600s haled from the days when loudspeakers were as characterful as a tipsy Boy George on the Parkinson Show. In 2007, where so many boxes are well-honed variations on a theme set many years ago, the original SL6s were a breath of fresh air. Small two-way 'speakers with unusual styling, ‘space-age’ computer aided design work to their drive units and the first copper dome tweeter ever, they were certainly different. The 82dB efficiency was outrageous even by the lowly standards of the previous decade, meaning that only the likes of a Krell could truly light them up. The SL600 added the ‘high tech’ metal cabinet, and made the SL6 package sound like no other boxed loudspeaker around - by comparison, the likes of the Acoustic Energy AE1 was boxy and wooden. Me, I hated the SL600s and still do – they’re far too ‘Radio 3’ for my tastes, but several classical music lovers I know hold them in even higher estimation than the Quad ESL57s and 63s they sold to buy their SL600s. Different strokes for different folks, but I’ll concede this was a speaker that genuinely moved the game along and radically transformed the eighties speaker scene. DP speakers are extremely long lasting. That PVC and Kobex woofer may be inefficient, but boy does it last well. The copper tweeter is similarly robust. It’s good to know that the SL600s can still be serviced - Celestion themselves no longer support the model but there are specialists such as DK Loudspeaker Services (+44 (0)1708 447344) that can help. Apart from the drive units, the main consideration when buying a pair of SL600s is the cabinet. Whilst Aerolam is very rigid, it’s also rather soft. Dented cabinets aren’t unusual, and are not something that can be patched up with wood glue and plastic wood! Small dents won’t affect the sound but anything larger effectively relegates the speakers to the role of parts donor. Cosmetically,
"a seriously engineered design that radically transformed the eighties speaker scene..." loose after a while, and affect the speed and impact of sound.
BUYING SECOND-HAND Although far from universally loved, the SL600s still have a cult following. Unlike the SL6, prices for the SL600 are higher than you might expect for a twenty year old design. Whereas as little as £30 to £150 should find a pair of working SL6s, you need more like £200 to get hold of a pair of the ‘600s – and this would be for a tatty pair. For a mint and boxed set of SL600Sis, with grills and possibly even stands you could be looking at anything up to £500. Although not cheap, these
the early SL600s mark very easily. My own pair are covered in scratches where careless guests have placed car keys on the top. The Si version used a much tougher paint, but it can still be marked. The good news is that, if cosmetic appearance concerns you, they're easy to respray. To sum up, if you enjoy a transparent sound and have a fairly powerful amplifier, then the SL600s could suit you well. Find a pair in good condition and they’ll not only sound surprisingly able for their age, but also provide years more service. You can also be rightly proud in the fact that they truly “don’t make ‘em like this anymore”!
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MAY 2007 HI-FI WORLD
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