SPL Tube Vitalizer

The SPL Tube Vitalizer is based on findings of psychoacoustics and audiometry. Its filter network is one of the few patented filters. It makes the richness of detail of audio signals more audible. Interventions in the sound image are more of a musical nature.

Music productions sound more natural, lively, differentiated, easier to understand, more deeply layered and more widely spread apart.

These are the five controls of the Vitalizer core circuit. Drive controls the level going into the filter network. The bass emphasizes a soft or hard tone. The coil filter (LC) makes the bass pithier and the compressor catches level peaks.

Mid-Hi Tune sets the frequency of operation above which frequencies are boosted and below which frequencies are cut. Process Level adjusts the intensity of Mid-Hi Tune and bass.

In addition to the SPL Tube Vitalizer core circuit, the Tube Vitalizer has a high frequency and harmonics processing stage with Frequency and Intensity controls and switchable coil filter (LC) as well as compressor.

The switchable tube stage is constructed with three tubes: first, left and right pass through their channel output tube, then the channels pass jointly through the third tube as a stereo signal. As a little treat, the SPL Tube Vitalizer offers a shunt limiter.

This limits the level according to a characteristic curve tuned to the tubes and provides the signal with a sonic effect similar to the saturation effect of analog tape machines.

A key feature of the SPL Tube Vitalizer is the unmasking of superimposed sound components. The Vitalizer thereby relates the time of perception of a frequency to its amplitude. Through a minimal temporal offset of loud frequencies, quieter, previously superimposed sound components are “de-masked” and thus become audible.

The non-linear sensitivity of the human hearing is described already in the 1930s by the “Fletcher-Munson curves”. These “curves of equal loudness” (today defined by the standard ISO 226:2003) illustrate the equal perception of loudness as a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones.

The SPL Tube Vitalizer adapts the frequency spectrum to the curves of equal loudness, which improves the loudness perception in particular.