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SPL Stereo Vitalizer Jack

Psychoacoustic Enhancer By Derek Johnson
Published July 1998

SPL Stereo Vitalizer Jack

SPL's acclaimed Vitalizer design has always been a bit harder on the wallet than other manufacturers' models – until now. Derek Johnson plugs in to their new enhancer for the rest of us...

In the world of aural enhancement, SPL stand, if not alone, then apart. Most enhancers or exciters produce their effect — brighter, more detailed sound — by generating certain amounts of controlled distortion. SPL's Vitalizer family uses an arcane mix of EQ, phase and level manipulation to produce punchier, more detailed mixes, without (so SPL claim) introducing extra distortion.

Another attribute that Vitalizers have been known for is their relatively high cost. But now that has changed with the arrival of the Stereo Vitalizer Jack. Debuting at a little over £230, the new model provides an opportunity for almost anyone to get in on the Vitalizer action.

The new processor comes in the familiar 1U rackmount format with a black and blue 'paint splash' finish, and as the name suggests, all the rear‑panel inputs and outputs are on unbalanced jacks (although the Vitalizer has been available in a jack version before, its connections were balanced). The connections are also duplicated on gold‑plated phono sockets (which would also make it suitable for hi‑fi use), and there's an internal power supply — a nice touch at this price. One other internal feature of the new Vitalizer, common to the whole family, is a bypass relay which engages in the event of a power failure. This is a welcome safety option for live use.

Set The Controls...

You may have noticed that the new Stereo Vitalizer has a superficial resemblance to the original Stereo Vitalizer, which was launched back in 1993. In fact, the controls on the clearly labelled front panel are virtually identical to that model. Taking these one by one:

  • The Bass knob works on the bottom end of your mix. Turning it to the left produces a more round, warm, soft effect, while moving it to the right produces a tighter, harder sound.
  • The Mid‑Hi Tune knob sets the starting frequency of a broad‑band shelving filter, allowing you to select where within the mid‑frequency range the Vitalizer starts processing. While the unit has a range of between 1kHz and 20kHz, most of the action will be in the 3.5kHz to 8kHz region.
  • The Process knob controls the amount of bass and mid‑range intensity. Basically, it gives you either more or less of the effect you've set with the Bass and Mid‑Hi Tune knobs.
  • The Brilliance control works on higher frequencies, without, somehow, actually boosting them in the way that many exciters do. The result is a more natural sound, less tiring on the ears, which adds clarity to the mix. To check out the effect of the Brilliance knob on its own, turn the Process knob full left. You'll find the Bass and Mid‑Hi Tune controls now have no effect.
  • The Stereo Expander uses a pretty straightforward technique (feeding opposite‑phase signals from one channel to the other) to take the stereo image beyond the boundary of your speakers. It works well, making the finer details of your mix even more apparent.
  • The Active/Bypass button is one to be used often while tweaking the Vitalizer, so you can compare the processed and unprocessed sound and make sure you're not overdoing it.

Unlike the original Stereo Vitalizer, there is no Stereo Expander bypass button, no Active/Bypass LED or any form of metering. An LED that flashed when things were getting a little too hot would have been useful.

All Right Jack?

The Vitalizer Jack really works — indeed, its effect on the bass end of a track is indescribable. I ran dancy drum box and synth mixes through it and got a kick to the lower frequencies that was impossible to achieve with EQ alone. Even some basic acoustic guitar and voice demos were lifted with a pleasing 'soft' bass effect.

'Detail' and 'clarity' are much over‑used words in mixing circles, but the Vitalizer Jack really does provide them in spades. The guitar/voice demos also benefited from the stereo expander, with backing vocals spreading out around my ears, leaving the lead upfront. Nice! The best approach, as with any enhancer, is to produce the best mix you can without the processor, and then add that fairy dust in the final stages. Also, keep double‑checking your processing against the original audio. While the SPL's treatment is very seductive, and not nearly as harsh as most enhancers or exciters, over‑use is still possible.

Essentially, the Stereo Vitalizer Jack offers the SPL magic at an accessible price. Audibly, there are no compromises, though there isn't quite the same amount of control as with SPL's top‑of‑the‑range models. However, this simplicity results in ease of use: you'll be getting the best from the Vitalizer Jack in no time.

There's not much else to say. Audition soon... and be prepared to get out your cheque book.


  • Most affordable Vitalizer yet.
  • Exceptionally easy to use.
  • Built‑in PSU!


  • No metering.


At £234, the Stereo Vitalizer Jack provides truly high‑level audio sweetening for the rest of us.