The Vitalizer MK2-T should – according to the manual – do all the things that our picky ears crave for: give the mids accurate transparency with a soft, unobtrusive sound, add depth, width and clarity to the stereo image, enhance highs with focus on their smooth and silky character, and last but not least provide deep, accurate and punchy bass. It sounds too good to be true and I considered the SPL’s text to be the usual overstatement. I could not be more wrong.


FRONT SPL Vitalizer MK2 T

The SPL’s Stereo Vitalizer MK2-T is the latest incarnation of their already successful “vitalizing” units. It is actually a sound shaping equalizer that employs clever circuits to manipulate the sound in harmony with the well-known psychoacoustic principles and thus enhance the sound without negative artifacts. It is not a unique device in existence – there are other sound enhancers available, from rather cheap (Behringer SX3040 Sonic Exciter, BBE Sonic Maximizer 482i, Aphex Aural Exciter) to more elaborate pro solutions for serious work like Solid State Logic Fusion. I haven’t heard the SSL Fusion yet but among the others the SPL Vitalizer MK2-T is a clear winner.

Getting started

The SPL Vitalizer is deceptively simple with XLR/TRS inputs and outputs and only few controls on the front panel:

The DRIVE for setting the “sensitivity” of the Vitalizer to the incoming signal. A clip LED light lets you know if you are running the unit too hot.

The BASS control contours the bass towards tighter and drier sound or towards the punchier and warmer sound.

The BASS COMPRESSOR works only in the bass frequencies. Threshold, attack and release are adjusted automatically.

The MID-HI TUNE control selects the starting frequency of shelving filter between 1KHz and 22KHz. everything above the set frequency is processed.

The PROCESS control must be turned from its off position to hear the effects of the Bass or Mid-Hi Tune settings. The more “processing” is applied the more profound is the alteration to the sound. This is achieved by changing the ratio between the Bass and the Mid-Hi Tune.

The LC-EQ sends the signal through a passive coil-condenser network to emulate Pultec-style EQs. In general this is the right control for making vocals stand out and add the mix silky transparency and clarity.  The amount of the “LC-EQ” is controlled by the INTENSITY knob.

The STEREO EXPANDER control is the only one that does exactly what it is supposed to do: enhances the width of the stereo image.

The ACTIVE button allows for comparing processed signal with a bypass mode.

SPL Vitalizer MK2 T

The manual recommends to start with Mid-Hi Tune at 3.5kHz and the Process control at 1 o’clock. After two months with the SPL Vitalizer I acknowledge this approach to be the safest – that is to apply reasonable amount of the processing and trying to hit the sweet spot by fine-tuning the “cross-over” frequency with the Mid-Hi Tune control. Only then use the other knobs to further improve what you are hearing. It does not mean that the Mid-Hi Tune or Process controls become untouchable, not at all – in the Vitalizer everything is connected so more fiddling with the Mid-Hi point may be beneficial at some later stage. Actually it only depends how much time you want to spend on polishing the sound: the MK2-T Vitalizer allows for quite fast intuitive fixes but if you want the best result take some extra time to achieve perfection. For example, with Sergei Edelmann´s otherworldly recorded piano (Chopin, Ballades, Triton OVXL-00045) the setting of 14KHz was just right. One step above or below spoilt the magic.

To get a grip on what turning the pots of the SPL Vitalizer really does, as easy as it seems, is not easy at all - especially for anyone used to work with graphic or parametric equalizer. Another example, the bass control adds roundness and weight to lows (turning left from the center position) or adds contours to lows (turning right from the center position). I would expect increasing the bass amplitude but in reality turning left creates a shallow dip centered at around 55Hz until around 10 o’clock when the dip becomes a broad peak. Turning right creates a higher-Q notch until ca 4 o’clock when the notch is flips into a peak too. The Process affects further how big is the amplitude so one would say that it makes no difference whether the Bass or the Process are manipulated as there is overlap for both the controls. Yet the bass quality differs when more or less similar frequency curve is achieved by low Bass and high Process settings or vice versa. Dtto for the coupled LC-EQ and Intensity knobs that are used for highs frequency enhancement – nothing is quite as it intuitively appears especially when the Mid-Hi Tune and Process controls also affect the treble too. While the Mid-Hi Tune sets the frequency above which the sound is enhanced, the LC-EQ and Intensity extract some frequencies from this process. It took me hours and hours of twiddling with the controls before I somehow understood what the knobs really do and after two months I still would not call myself an expert on the Vitalizer.

SPL Vitalizer MK2 T bass curves

Fig.: What happens to bass when turning the Vitalizer´s BASS pot to the right and to the left

The SPL Stereo Vitalizer MK-2T is designed for mastering and post-production work. It is not a surgical EQ neither it can replace a parametric EQ simply because you have no real control over the exact frequencies assigned to the pots. It is like the circuitry of the SPL Vitalizer strives to cumulate the knowledge of 60 years of recording industry into one convenient 1U unit. I think this is the real beauty of the device – in its simplicity it is really powerful and lets you do amazing things without the sound getting nasty. Ever.

On music

The SPL equipment has a great reputation for not interfering with the signal when by-passed. This is always the first test I perform with any processor in the signal path – what is the use for an equalizer if it introduces noise, impairs dynamics or affects frequency balance? I am happy to report that the Vitalizer MK-2T is as transparent as the best high-end units I ever reviewed. In fact it is more transparent than the vast majority of them. Then the most hilarious moment comes by pressing the Active button: nothing bad really happens. With all the controls at their “off” positions the signal passes through the triode and the only quality it acquires is a touch of better dimensionality and a tint of analogue warmth with no loss in dynamics or apparent noise (with the S/N ratio of 99dB the SPL Vitalizer is beyond the red book CD capabilities and far ahead of vinyl or tape anyway).

I used the SPL Stereo Vitalizer MK-2T for CD released material - that is as a stereo mastering equalizer on final mixes that were already mastered for better or worse. I compared it directly to DSP-powered equalizers like Accuphase DG-58 and Behringer DEQ2496 as well as to SPL’s own passive PASSEQ parametric mastering device, plus I also had the Aphex’s Aural Exciter on hand. Signal cabling was AudioQuest Wild Blue Yonder and Redwood, power amplifier was the TAD M-2500. The monitoring was done through the full range TAD E1 speakers.

There was not a single instance that I could not improve the sound with the Vitalizer. The level of such an improvement wass dependent on the quality of the source material, of course.


SPL Vitalizer MK2 T rear


On already brilliantly mastered music the SPL Vitalizer´s contribution was small yet it was there. It introduced a bit of warmth and helped the recorded material radiate light and joy. Also, for hifi enthusiasts, the Vitalizer may help correct acoustics of your room by changing the spectral balance of the playback chain, especially in dull rooms covered in popular PUR foams and thick carpets. Even if none of the knobs is turned the Stereo Expander circuit is granted to bring extra pleasure. It works on the well-known principle of detecting the off-center sounds and sending them with inverted phase to the other channel. In the SPL Vitalizer this circuit is fully mono compatible and uses one of the triodes. Not only music grows by delicate separation of images and wider stereo base without softening transients or dynamics - it also acquires a touch of analogue feel. Maximum values of the Stereo Expander pot were at around 11 o´clock (8), turning it more suppress the phantom center image too much for me. With solo instruments (piano, violin, solo vocals) lower setting was better. I can imagine more extreme settings applied during mixing, e.g. on drums.

The Mid-Hi Tune setting is the key parameter and 3.3KHz worked the best for me for the most of well-recorded music, 14KHz alternatively for modern too brightly mastered albums. Take your time with it – I spent nearly 2 hours by in the listen-adjust-listen process with Nicola Benedetti (Fantasie, Decca 476 3399) and achieved electrifying sweet sound of her violin on a soft and embracing pillow of Royal Liverpool Philharmonic orchestra. After that I spent whole night just by listening in the repeat mode and could not stop before morning.

The magic started to happen as soon as I moved to other music genres. FLA (Improvised Electronic Device) and Front 242 (00:00:02:42 Angels vs Animals) are both nicely recorded hard dance floor affairs and without the benchmark of “how it should sound” more extreme settings on the SPL Vitalizer (especially with the Process control) made a real difference. 20 minutes into the CD I achieved a setting where the deep bass started making cracks in walls and my sofa bounced on the floor while highs were like strobe beams flashes, precise and controlled. The intelligibility of sound was dramatically improved and I could increase the volume 4dB above my usual - already loud – standard. It was quite an addictive experience and when I hit the stop button of my player my ears were pressurized the similar way like at a loud live concert, this time in uber-resolution.

Final thoughts

Over one weekend I compared the Vitalizer with the reference mastering parametric SPL PASSEQ equalizer. To achieve similar sound I had to work much harder with the PASSEQ and the result was never completely the same. No matter what I did the SPL Vitalizer always had the edge on the PASSEQ with special radiance that made the music sound lifelike rather than technically correct and “just” tuneful. Is it because of the valves in the signal path that add harmonics so much liked by human hearing? Or is it because saturation effects of coils? The fact that after 30 years of digitalizing the way the music is recorded and mastered we get back to imperfect hardware to make sound digestible is both remarkable and pitiful.

SPL Vitalizer MK2 T controls

Some more highlights

Except of the Bass control all the pots are stepped so it is easy to recall any previous setting. If you consider that each control has ca 20 steps and there are 5 important controls to affect the sound it gives 20x20x20x20x20 combinations. If only 15% of them is really good match then you are left with 0.5 million setting options.

I found the SPL Stereo Vitalizer indispensable for processing early digital music from 80´s. These were often just transfers from tape or even vinyl masters and lack spark. In exchange they have natural dynamics which are missing in their remastered versions. The Vitalizer does the remastering job easily without removing the headroom.

A wishlist

The tube complement contains two JJ ECC83S triodes, unlike the Sovtek 12AX7 specified in the manual. At least in my unit and I am happy for it as the JJ triodes are much better in S/N ratio. I did not try to replace the tubes with some NOS valves or other brands yet it may be worthwhile for owners. Replacing the tubes is not a straightforward procedure as they are held in place by not just pins but also by an anti-resonance clamp. To replace the tube you need to dismantle the Vitalizer completely, removing both upper and lower lids of the chassis.  I wish this process was easier.

One cannot perform cuts with the SPL Stereo Vitalizer MK2-T. Integration of a simple 1-band parametric EQ with selectable Q-factor would turn the Vitalizer into a killer. Even without it the Vitalizer still is a killer.


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