JBL 6208

Active monitors are all the rage in the project studio market at the moment. Hugh Robjohns checks out a weighty contender from American loudspeaker giant JBL.

JBL have a long history in the professional loudspeaker industry, not only in the design and manufacture of drive units and systems for PAs, but also in professional studio monitors of all sizes. The Model 6208 Bi‑amplified Reference Monitor reviewed here is a professional nearfield loudspeaker system intended for broadcast and recording applications.

Physical Design

The 6208 is part of JBL's 4200 series of studio monitors, which currently also includes a pair of passive two‑way loudspeakers, the 4206 and the 4208. These are very similar loudspeakers, fundamentally differing only in the size of bass‑mid driver (of six and eight inches in diameter respectively). The 6208 is, to all intents and purposes, an active, self‑powered version of the 4208.

This entire range of loudspeakers features a rather intriguing form of front baffle which JBL call a 'Multi‑Radial Baffle'. The idea is to try to align the acoustic centres of the two drive units in the vertical plane, so that sound waves emerging from both drivers travel the same distance to the listener — that is, they are time‑aligned. This is particularly important in the crossover region of the unit, where both drivers are contributing to the sound output, and it's claimed that the design helps to improve stereo imaging and perceived frequency response around the crossover region.

The relative dimensions of the two drivers mean that, to achieve a correct time‑alignment between them, the woofer must be mounted forward of the tweeter, so that the voice coils of the two units lie directly above one another. The concept is certainly not new — many of the larger KEF and B&W monitors designed in the '70s and '80s placed the mid and high drivers in separate enclosures stepped back from the front of the bass cabinet, to achieve exactly the same effect. However, these separate stepped enclosures had hard edges, which often caused acoustic diffraction in an unhelpful way, and JBL have attempted to overcome this shortcoming by making their front baffle in a smooth and curvaceous form. The easiest and most descriptive way I can find to describe the visual impact of JBL's 'Multi‑Radial Baffle' is to liken it to the profile of an extremely well developed beer‑belly!

There is also an elliptical basin around the tweeter to aid in HF dispersion. The unusual baffle shape results in the voice coil of the bass unit being directly below that of the tweeter, thus achieving the desired time‑alignment, although, because of the profiling, the woofer is not itself vertical, but is tilted back slightly.

Tech Talk

The drive units in the 6208 are both made by JBL: the woofer is a 200mm unit with a long‑throw voice‑coil design and fully shielded magnet assembly, and the 25mm tweeter is a gold/titanium hybrid dome unit. (The other 4200 series monitors manage with a straight titanium dome device.) A protective grille is fitted in front of the bass unit, but this can easily be pulled away (a cut‑out is provided on the baffle to make the task very simple), and the tweeter has a metal bar to provide some level of physical protection.

The drive units are rated continuously at 75W on pink noise, with a peak capability of 300W, so they are more than capable of providing the kind of level anyone could tolerate in a nearfield situation. The loudspeaker is quoted as having an overall frequency response of 60Hz‑20kHz, and is claimed to be capable of producing useful energy (at ‑10dB) down to 38Hz.

The black‑stained wooden cabinet measures exactly the same as JBL's 4208 monitor, at 451 x 286 x 229 mm (x W x D) and has a large, 65mm undamped port at the rear of the cabinet, just below the centre. These speakers are a little on the large side for nearfields, and although they will sit quite happily on the meter bridge of most large studio consoles, semi‑pro and home studio owners will probably find them easier to use as midfield units on stands arranged behind the desk.

Built into the loudspeaker cabinet at the top of the rear panel is a self‑contained, fully shielded amplifier and active crossover pack, which makes the 6208, at 13.3kg, rather heavier than its passive sibling the 4208, at 9.3kg. The two 50W discrete‑circuitry power amplifiers have apparently been designed to use very little negative feedback, and JBL claim they have extremely low distortion and no slew‑rate limiting. A reasonably large heatsink provides cooling for the amplifiers, but the units run only moderately warm in use.

The line‑level active crossover integrates the two drivers at 2.6kHz but, unusually, there are no facilities to fine‑trim the output level at either end of the frequency spectrum, nor to adjust the input sensitivity. Having said that, the nominal input level is selectable between the professional +4dBu and semi‑pro ‑10dBV 'standards', depending on which form of input connection is used. The rear panel carries a Neutrik 'Combi‑jack' XLR socket, and JBL have arranged for the electronically balanced XLR input to provide a nominal sensitivity of +4dBu, whilst the central jack socket input is designed for ‑10dBV signals.

Also on the rear panel are an IEC mains inlet, a suitably identified fuse holder, and a rocker‑style on‑off switch — the mains input voltage is fixed at 250V and cannot be altered by the user. There are no indicators on the front panel to show when the loudspeaker is powered, nor when the amplifiers are being stressed (ie. over‑temperature or clip warning indicators). I was unable to determine whether there is any form of protection circuitry incorporated in the amplifier pack, but the JBLs proved more than capable of handling everything I asked of them, including a short period of deliberate abuse with a very bass‑heavy signal (all in the name of research, you understand).

Humming Along

The first thing that struck me when I powered up one of the monitors (with nothing connected to its input) was a rather obvious buzz and a little hiss. The hiss could only be heard at close quarters from the tweeter, but the buzz was quite loud and could be heard clearly throughout the control room, even above the racket from the obligatory studio Mac computer. The hiss was nothing to worry about, but the buzz definitely was; thinking that it was picking up some kind of interference on the unterminated input (although its CE marking should guarantee that it would not be susceptible to such problems, of course), I plugged the loudspeaker into the desk monitoring (which I already knew to be completely clean). Unfortunately, it still buzzed and when I powered up the second monitor it performed in exactly the same way, with the same buzz.

To try to isolate the source of the noise (was it related to the mains or signal inputs?), I unplugged the monitors from the mains outlets, and before the amplifiers died I discovered that the speakers became delightfully buzz‑free. Further investigation suggested that the buzzing was not emanating from the woofers, as I'd first assumed, but was actually transmitted acoustically through the rear port. It appeared that the mains transformers in the amplifier packs were the source.

Just in case the local mains power feed contained some nasty harmonic signal which was upsetting JBL's transformers, I tried listening to the speakers at different times of the day (and night), at the weekend as well as during the week, and at a different location 20 miles away — but all to no avail. The 6208s, as supplied for review, buzzed. A second pair summoned from JBL's office in the UK also hummed. They weren't quite as bad as the first pair, but the buzz was still completely unacceptable and would be very obvious in all but the most noisy control room environment.

Both sets of speakers were clearly 'demo units', but even so I would have expected a manual; in fact, neither set was supplied with any kind of handbook, and the second set didn't even come with mains leads.

Overall, the JBL 6208s were something of a disappointment to me. The acoustic buzzing is obviously inexcusable...

Listening Test

Disregarding the buzzing (as far as it was possible to), the 6208s actually produce quite a nice sound. In my experience, JBL speakers sound like New Yorkers speak — they always seem to be a bit hard and brash. However, I believe that there's a trend within JBL to produce a more modern sound quality, and certainly the 6208s manage to produce wide and well‑defined stereo images. They're capable of stable imaging over a useful working area, and create a reasonable sense of spaciousness on suitable recordings. In fact, initial impressions are very favourable — these speakers have the kind of presentation which is immediately exciting and involving — the treble is crisp and well extended (with a typical metal‑dome precision) and, apart from a little 'bloom', the bottom end is quite respectably controlled too.

Compared to my normal references (professional PMC AB1 transmission line monitors and PMC TB1 nearfield monitors, Tannoy Little Reds, and BBC‑designed LS3/5As), I felt the JBLs were a tad 'bloated' in the lower mid‑range. Irrespective of the sound source, I kept wanting to tweak out a little bit in the 400‑800Hz area — maybe only a dB or two — and this did contribute to my impression of a slightly muddy or thick sound. Thinking the speakers might be sensitive to placement, and that this was the cause of the perceived bulge in the frequency response, I experimented at some length, but apart from the fact that they don't like to be close to a rear wall (because of the rear‑firing port), the kind of sound obtainable from the 6208s appears to be largely independent of their positioning — the best results were obtained in 'free‑space', well away from walls and with a clear, direct path to the user's ears.

Reviewing loudspeakers is never easy, because the perfect loudspeaker has not yet been invented, and even if it was in development you'd find it hard to get a dozen people to agree on what 'perfect' means! Every designer chooses a different set of compromises and every listener has their own particular preferences. My comments must be taken with the understanding that they are purely personal opinions, albeit given with the benefit of many years of listening and working with a wide variety of professional‑quality monitoring systems.

To my way of thinking, a professional monitor should be as faithful to the original sound as possible, so that meaningful decisions can be made about positioning microphones and processing their resulting signals. However, in my experience, many American loudspeakers (and JBL in particular) seem to have a noticeably coloured, and therefore inaccurate, tonal balance. I found that JBLs 6208s initially produced an impressive and exciting sound, tending to flatter most sources, and that everything sounded almost larger and crisper than in real life. However, over extended listening periods I found the loudspeakers to be quite fatiguing to work with, and they produced a bit too much coloration to be classed as true reference speakers — especially in the lower mid‑range. And then there's the buzz, which masks subtle low‑level signals completely and could result in you not spotting similar flaws in the recording itself!

The 6208s are capable of producing a lot of sound (I hardly think anyone would have cause for complaint on that score), and they are also quite analytical (probably thanks to the metal‑dome tweeters). The tiniest clicks and ticks on a rather dodgy DAT recording were easy to spot and, apart from the slight lower‑mid 'bloom', the bottom end is surprisingly powerful and reasonably well extended. However, the bass had an almost artificial quality and I found it very hard to make accurate assessments when equalising at the bottom end of the spectrum.

Conclusion

Overall, the JBL 6208s were something of a disappointment to me. The acoustic buzzing is obviously inexcusable, and the fact that both speakers in both sets suffered the same defect does not bode well — I think a redesign of the power supply is urgently required. The speaker's tonal balance, whilst nodding in the direction of better accuracy and fidelity, still seems quite coloured, and because of that I would hesitate to choose these as a main monitoring system. However, the 6208s might make a good choice for a replay system where you want to create an impressive, flattering, and involving sound.

Despite my overall negative tone in this review, the 6208s do have some saving graces. They are very easy and convenient to use, they seem to be well built and should prove very robust, and they look the business.