## A frequecy dependent phase manipulation tool.

Device/Module Wishlist

Original topic on PlanetZ: https://forums.scopeusers.com/viewtopic.php?t=11155

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Posted: Mon Dec 22, 2003 3:49 am
by Marc de Ruiter
Could anybody create a device like this? (This a quote from an article of Paul White in SOS magazine)
PHASE MANIPULATION
BBE's Sonic Maximizer system is based on the premise that most audio systems introduce unwanted phase shifts into the audio signal, resulting in a lack of clarity. To remedy this, the BBE processor splits the audio signal into three frequency bands, then applies different delays to each band to restore the original phase relationship of the harmonics making up the sound. On the models I've used, frequencies below 150Hz are delayed by around 2.5ms, while those between 150Hz and 1200Hz are delayed by about 0.5ms. Frequencies above 1200Hz are not delayed, but do have some form of dynamic control (compression/expansion) applied to them so as to enhance transients. Unlike the Aphex process described later, the BBE principle does not add new harmonics, but rather attempts to realign the relative phase of existing harmonics, as well as using dynamic processing to emphasise transients.
Essentially, the controls comprise a low-end EQ control to help balance the bass end against the enhanced top end, and a Definition control. LED metering shows the extent of the dynamic processing applied to the HF band and, on the models I've used, there has also been an Auto/Manual button. In Auto mode, the dynamic treatment of the HF band is determined by the dynamics of the mid-band signal; in Manual mode, the high band is subjected to a fixed degree of dynamic processing. The Definition control affects only the dynamic, high-band processing level -- the inter-band delays are always active when the process is engaged.
Setting up a BBE Sonic Maximizer usually entails selecting Auto mode, adjusting the Definition control to bring up the high end, then using the Lo-Contour control to make up for any lost bass end. Overall subjective brightness is increased, but the sound lacks the incisive (and sometimes fatiguing) edge of the harmonic exciter.