BSG Technologies QOL “Signal Completion Stage” (TAS 220)

Audio’s Magic Bullet?

The history of audio is littered with the skeletons of “breakthrough” signal-processing technologies that reportedly improved the listening experience. From the “Hafler Hook-up” of the 1960s to today’s sophisticated DSP-based systems, there’s been no shortage of attempts to enhance music listening via manipulation of playback signals.

The problem is that none of these systems, at least in my experience, have worked. They end up sounding contrived and hokey. Rather than bringing us closer to the absolute sound, these technologies take us further away by creating “effects” that are supposed to mimic the live experience but end up calling attention to themselves as effects. I’m not talking about the absurd DSP programs on AV receivers such as “Concert Hall” or “Jazz Club” that attempt to synthesize acoustic reflections, but rather about the long list of “spatial enhancers” and other “psychoacoustically” inspired analog-domain technologies, usually involving sum-and-difference signals, delays, and filters.

I thus regarded with tremendous skepticism the claims of BSG Technologies for its QOL (rhymes with “coal”) technology incorporated into a device called a “Signal Completion Stage.” QOL is a playback process that reportedly restores the natural phase relationships in audio signals, resulting in improved sound. The company behind QOL, BSG Technologies, plans to license QOL to hardware manufacturers in a variety of fields including car audio, cell phones, telecommunications, and motion pictures.

To demonstrate QOL, BSG Technologies developed a $3995 stand-alone box (the “Signal Completion Stage”), the subject of this review. Although this box allows evaluation of the technology, the optimum implementation is within a preamplifier, DAC, or other component. QOL decoding is so simple that an analog implementation can be realized with about three square inches of circuit-board real estate, and in the digital domain with a very small amount of processing power running on a chip. Given the development time of high-end audio products, it will likely be some months or years before QOL is available in products from a variety of high-end manufacturers—if it ever is.

The device I received for review is fairly elaborate, offering four analog inputs on both RCA and XLR jacks, dual pairs of outputs on RCA and XLR jacks, fully balanced operation from input to output, source-switching, a mono button, and a remote control. A “Bypass” button allows you to switch QOL decoding in and out of the circuit, which is convenient for listening comparisons. The Signal Completion Stage integrates into your system either between your source components and the preamplifier (thus the multiple inputs), or between the preamplifier and the power amplifier. The device is pure analog, with no analog-to-digital or digital-to-analog conversion. BSG Technologies sells the device directly to consumers and offers a 30-day money-back guarantee.

Despite my skepticism, I listened to an early prototype nearly two years ago and was encouraged by what I heard (see my report in Issue 201). BSG Technologies is quick to stress that QOL isn’t a signal-processing technology, in that it doesn’t add anything to the signal that’s not already present. Moreover, it differs from the myriad techniques used in the past (extensively referenced in the QOL patent application’s “prior art” citations), most of which involve extracting the difference channel from a stereo signal (left minus right), equalizing, delaying, filtering, inverting, or performing other psychoacoustically based manipulations of that difference signal, and then mixing it back into the L and R channels. The BSG Technologies Web site offers this explanation: “Instead of ‘adding’ a host of processing techniques intended to create ‘effects,’ we have simply found a way to extract information already present in the recordings, but otherwise hidden in conventional reproduction.”

The patent-application abstract offers a more detailed description: “The present invention relates to an apparatus and method for redeeming otherwise closed and concealed information contained in audio signals. This includes both the primary reference signal, and a plurality of redundant duplicate signals, substantially identical except in relation to magnitude and phase, for the purpose of unfolding, or opening the audio signal content into layers that result in an omni-directional acoustic signal, representing the sound as it would behave in nature. The audio reproduction system uses an in-phase circuit and a separate phase layering technique circuit to drive independent multiple mixed channels to produce an open, substantially complete sound from a discrete audio signal, for the purpose of enabling a substantially complete audio signal to be formed, or to transform existing incomplete audio into a substantially complete audio signal.”