Paul White finds out more about Perfect Pitch Music's intriguingly named Francinstien stereo enhancement system.

Let me satisfy your curiosity at the outset by informing you that the Francinstien unit, from Perfect Pitch Music, appears to be a hybrid processor that combines specialist EQ, harmonic excitement, and stereo width enhancement. It may be used to 'open up' entire mixes or can be used to process parts of a mix by, for example, being used to process a stereo subgroup.

Apparently, the unusual spelling of 'Francinstien' is due to the fact that it is an acronym for FRequency Adaptive, Non-linear Crosstalk Injection Network for STereo Image ENhancement — so now you know. The accompanying literature includes a discussion on the usage of pan pots to create the illusion of stereo in modern record production, and explains that this technique leaves out many of the essential auditory clues, including the time delay between signals arriving at one ear and the other, which happen in real life when sounds come from the left or right.

Stereo width expanders of one sort or another have been with us for many years, the simplest being to feed some of the left channel signal, out of phase, into the right channel and vice versa. Francinstien appears to combine this kind of 'sum and difference' approach with some form of filtering, so that the effect occurs predominantly at low frequencies.

THE HARDWARE

Francinstien comes in an unassuming, light grey, 1U box decked out with just six knobs and a couple of switches; the power switch is around the back, built into the IEC mains connector. The two audio channels may be accessed either by conventionally wired, balanced (transformerless) XLRs operating at a nominal +4dBu level or via unbalanced jacks at the -10dBv level commonly used in home studios. Separate terminals are provided for the chassis ground and the circuitry ground, allowing the user to either link the two together or opt for some form of ground lift connection.

All the circuitry is contained on a single glass fibre PSU and power comes from a small, torroidal transformer mounted at the opposite end of the case. The circuitry is all analogue and appears to be based around a number of operational amplifiers; I could see no delay chips, so I'd surmise that the time delays used in the Shuffler circuit are brought about by phase shifts.

The front panel rotary controls affect both channels simultaneously, as do the Bypass switch and the LF Emphasis button. A bi-coloured LED is used as a status indicator for the Bypass switch, red depicting bypass and green showing the effect to be active. Somehow, this seems to be the opposite of what you might expect, but no problem.

The first control is Space, which determines the amount of 'Shuffling' going on and serves to both expand and clarify the stereo image. Because some degree of centre-image cancelling appears to occur when the Space control is advanced, there tends to be a change in tonality on some material which can be compensated for by using the other EQ and harmonic enhancement controls. These controls may also be used in a creative way to make a mix appear rather larger than life.

The Depth control acts as a subtle but effective LF equaliser and there are two switch settings, offering Warm or Dry tonalities. Warm is based on a shelving filter response and produces a deep, wide bass sound, while Dry is a bandpass filter giving a more focused and punchy result. No details as to the filter characteristics or EQ ranges are provided.

Mid/Hi Tune and Lift work together, Tune selecting the area of the upper mid range that needs bringing out, and Lift applying boost in the chosen region. This section is again based on conventional equalisation techniques, while the Harmonics control works in a similar way to that of an Aural Exciter, adding artificial harmonics to the signal to enhance detail and to add clarity to the HF end of the spectrum. Finally comes the Output level control, which is used to set the processed sound to the same level as the bypassed sound for easy A/B comparison.

"There seems to be a high level of interest at the present time in devices like Francinstien that can add that magic 'something' to a mix..."

FRANCINSTIEN IN ACTION

While testing this unit, I connected a Box soundstage meter to the system to see if I could determine what was going on in domains other than the subjective. This indicated that when the Space control was advanced, the two channels contained a significant amount of out-of-phase information and that the central image was being pulled back. In other words, where the same sound appears in the left and right channels (central image), it is reduced in level compared with the sounds panned to the left or right. Any slight changes in balance that this causes — which appear mainly at the low and low-mid end of the spectrum — can be remedied by careful use of the available EQ controls.

Subjectively, the effect of increasing the Space control didn't seem that different to the more basic expansion techniques that don't employ filtering, but that isn't to say that it was not effective. The stereo image seems to move out from the centre and can even appear to be a little wider than the physical positioning of the speakers. But if the Space control is advanced too far, a hole begins to appear in the middle of the mix, with sounds appearing to be polarised either to the left or right. As with any creative process, some measure of judgement is essential.

The EQ controls seem to have been designed so as to have a wide, smooth effect without introducing any nasty peaks or dips into the response. They have a more than adequate range and, if used sparingly, can prove very effective and musical. Bringing in the Harmonics control adds the familiar openness and clarity to the top end of the sound — but again, restraint is necessary if the sound isn't to become harsh. In combination with the Space control, the Harmonics control works well in creating the illusion of 'space' around individual sounds.

SUMMARY

The Francinstien unit works well as an overall stereo enhancer, but I remain unconvinced of the sonic advantages of the Shuffler circuitry as compared to the more common inter-channel phase reversal technique. The former does create a subtle widening of the stereo image but, to my ears, no more so than can be achieved with less sophisticated units.

The equalisers are far from unique in their action, but their characteristics seem well chosen for general enhancement. They are certainly useful in cleaning up the mid range or adding a touch of weight to the bass end without upsetting the overall tonality of the mix. The same is true of the Harmonics control, which does essentially the same job as the original Aphex Aural Exciter — the first commercial unit to exploit this technique.

Subjectively, the Francinstien unit is very quiet, and the quoted figures of -80dB unweighted seem surprisingly modest. Distortion and frequency response figures are rather less meaningful, as any process that introduces equalisation and harmonic enhancement will affect these parameters to a greater or lesser extend depending on the control settings. The quoted bandwidth in bypass mode is extremely flat from 20Hz to 20kHz and, according to the printed spec, only 3dB down at 860kHz (!), but how this relates to the process mode is uncertain.

There seems to be a high level of interest at the present time in devices like Francinstien that can add that magic 'something' to a mix — especially from the broadcast sector. That the Francinstien unit achieves this in its own way is beyond doubt, though it does face stiff and varied competition in what is becoming an increasingly competitive marketplace. How successful it will be remains to be seen, but if you get a chance to hear one demonstrated, I think you'll agree that it does make a constructive contribution to the sound of a mix. Whether Francinstien will ever become a real 'monster' is another matter entirely; I'd tend to regard it as a rather nice exciter-type processor with the stereo width expander as a useful bonus, rather than the other way around.

Further Information

Francinstien £585; valve option £735. Prices inc VAT.

Baccus Professional Audio Ltd, (Contact Details).