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.
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 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 analogue tape machines.
A key feature of the SPL Tube Vitalizer is the unmasking of superimposed sound components. The SPL Tube 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 Adaptation to Curves of Equal Loudness
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.
