BBE 262

If you're suffering from muddy sounds, BBE's smallest Sonic Maximiser yet could be just the thing to clean them up. Hugh Robjohns puts on his gumboots and wades in.

The model 262 Sonic Maximiser is the latest and smallest in BBE Sound Inc's range, and brings the benefits of the Sonic Maximising process in a form that is both easy to use and extremely effective.

The Process

BBE's Sonic Maximising process has been designed to compensate for the common inadequacies of conventional loudspeakers and their passive crossover networks. Over the last 10 years, BBE engineers have studied a wide variety of loudspeaker systems and believe that they have identified the characteristics of both an 'ideal loudspeaker' and the corrective action required to make typical loudspeakers behave properly.

The problem that the BBE process is trying to overcome is the inherent envelope distortion that's caused by any filtering process but particularly by those processes associated with loudspeakers. Signals of different frequencies are delayed by different amounts as they pass through a filter, and so the timing relationships of the fundamental frequencies and harmonics are altered. It is claimed that this can be perceived as a loss of 'integrity' in the audio quality — sounds taking on a muddy or smeared character which, in extremis, can make it hard to differentiate between, say, an oboe and a clarinet!

The BBE 262's signal processing splits the audio signal into three bands: 20Hz‑150Hz, 150Hz‑1200Hz, and 1200Hz‑20kHz. The lowest band is delayed by about 2.5ms through the action of a passive low‑pass filter. The middle band is delayed by about 0.5ms through an active band‑pass filter (thereby causing high fundamentals or low harmonics to exit the unit before the lowest fundamentals). The highest band is not delayed at all; it's processed by a voltage‑controlled amplifier whose gain is determined by the average loudness of both the middle and high bands, so that the high‑frequency harmonic content can be 'optimised'. In the case of the 262, all this signal processing is performed within a single dual‑channel integrated circuit.

The Hardware

The 262 feels very solid and is surprisingly heavy given its diminutive size; the steel case is finished in a very attractive textured grey paint which adds to the overall impression of a high‑quality unit. The 262 can process two independent audio channels; although the handbook talks about using the unit to process stereo signals, there are no linking facilities for accurate stereo working. The rear panel has five quarter‑inch jack sockets, four of which are used for unbalanced inputs and outputs (up to +6dBu input and +17dBu output); the last is a footswitch socket to engage the signal processing remotely. Also on the rear panel is a square red button to turn the unit on, and a co‑axial 12V AC power socket — a suitable plug‑top mains adapter is supplied with the unit.

The front panel has four rotary controls and another square red button, which provides a bypass facility (replicated by the footswitch socket); the associated LED glows green when the BBE process is functional, red when bypassed.

The two audio channels each have a pair of rotary controls labelled 'Lo‑Contour' and 'Process' and these increase the relative amplitude of the lower and higher bands of the processed signals by up to 10dB at 50Hz and 5kHz respectively. In addition, the Process control activates the 'BBE Process', allowing the system to actively re‑balance the mid‑range and upper harmonic levels and introduce the fixed timing correction between fundamentals and harmonics.

Although there are no input level controls, or even a level meter, the 262 seems perfectly able to cope with a wide range of signal levels without overload or noise problems (in fact the signal‑to‑noise ratio is quoted as an impressive 112dB with processing active), and I experienced no interfacing problems at all when using the unit in nominally ‑10dBv systems.

The manual supplied with the 262 is well written and remarkably informative. Not only does it provide a useful description of the aims and nature of the signal processing, it also includes the complete circuit diagrams of the unit and full engineering alignment procedures. There are seven pages giving examples of typical operational uses and system connections and some very helpful advice about how the unit interacts with normal equalisation practices.

The Result

There can be no doubt that the 262 Sonic Maximiser modifies the signals that pass through it in a comprehensive way! The problem I had was in trying to judge exactly how effective the process was, because, as the two operational controls of each channel are increased, the output level rises — and quite considerably when the controls are fully clockwise.

One thing I'm always at pains to point out to people learning how to use EQ for the first time is that it's very easy to fool yourself into thinking that your equalisation attempts have made a sound source 'better', when in reality all you've done is make it louder and brighter. This is very much the case in point with the Sonic Maximiser, since it's been specifically designed to make the sound louder and brighter. The real problem is that the Bypass switch doesn't maintain the overall programme level and therefore switching the processing out always results in a dull and lacklustre sound, with the inevitable result that you become convinced that the 262 has magical properties which must be used at all times! Splitting the input signal at source and comparing the direct and processed versions on a mixing desk, where average levels can be matched more accurately, will let you appreciate the true benefits of the BBE 262.

Essentially, the spectral balance of harmonically rich programme is altered in such as way as to make it sound brighter, richer and 'more interesting', in a similar way to the effect produced by an enhancer, but possibly more 'naturally'. There is a down side to the BBE signal processing, however, and that's its tendency to increase and expose tape hiss or other electronic noise, and to compound this problem with audible pumping or breathing effects on some critical audio material.

I wasn't able to perceive a definite benefit of the re‑timed fundamental and harmonics, but the overall impression of the signal processing was certainly to make average and poorly‑recorded complex sound sources seem less muddy and indistinct. Care should be taken if a 262 processed signal is mixed with a non‑processed version of itself (if there are high levels of spill from another microphone, for example), as the built‑in processing delay can cause a mild phasing effect. Also, processing stereo signals is tricky because the difficulty of matching control settings between channels, combined with the automatic and dynamic level adjustments to the high‑frequency band, causes an unstable and constantly shifting stereo image.

The Conclusion

All in all, the BBE 262 Sonic Maximiser is well built and effective, and gives most sound sources — or, better still, complete mixes — extra clarity and weight. Although this is the baby of the range in terms of size and price, it manages to pull its weight on sonic quality and, providing it's used with care, it could be a cheap and cheerful alternative to equalising and compressing a demo master.