In professional audio parametric equalizers have long since replaced the graphic ones for their greater precision of intervention as well as a considerable decrease in phase alterations. In fact, in graphic equalizers, to flatten a response curve, one is almost always forced to use almost all of the 31 intervention points offered, but each band introduces a phase shift that is added to the adjacent one, with the result of creating rotations on the whole spectrum. With a parametric equalizer, in most cases two or three points of intervention with a precision of a single hertz are sufficient, which thanks to the adjustment of the Q factor width allow you to model the curve to your liking.
3 EQUALIZATION STAGES
Thanks to the processing power the bit One HD Virtuoso provides the user with three parametric equalizers that intervene in different points of the sound processing path. It is important to note that all three equalizers can be disabled or enabled at will.
1. CHANNEL EQ: it is the block used to flatten the emission of all the speakers of each front that should be adjusted with the most linear source possible (optical digital AUX input). Highlighting the corresponding curve, the Channel EQ allows you to hear the sound of the corresponding speaker. For each emission front or single channel the EQ provides 11 parametric poles and 2 FIR shelving type filters. To flatten the emission at the crossing points you can use all-pass filters and notch type filters to suppress any resonances in the passenger compartment. In the FIR configuration, 8 parameter filters are available, a Hi-Shelf (FIR), a Lo-Shelf (IIR) and two parametric points (IIR, full band) that can also be used as notch.
2. INPUT EQ: it is the equalizer that is used to manually flatten the selected input that can be strongly altered as in the case of an OEM Head-Unit with an equalization preset by the manufacturer. This equalizer block is useful for levelling out the sound differences between the sources as in the transition from a Hi- Res (already linear) player and an OEM Head-Unit connected to the master input. In this case the user avails of 8 + 1 parametric intervention points (FIR) + 1 Hi-Shelf (FIR) and many additional features such as:
i. Free selection of input fronts (FRONT L, FRONT R, REAR R, REAR R, CENTER, SUB) in order to unlink the input EQ. User can decide to keep the “All Fronts” default setting to apply the same input EQ, or by de-flagging this option, to work on each input independently.
ii. All-pass filters (2nd order) for each input front (FRONT L, FRONT R, REAR R, REAR R, CENTER, SUB) that can be free tuned (Fc, phase) by the user to linearize OEM phase algorithm.
iii. Quick sensitivity level adjustments 3 stages (ref, +3dB, +6dB), to boost input sensitivity and gain headroom when musical tracks are recorded quite below 0 dBFS (low). This function will be also available on DRC MP.
3. MAIN EQ: it can be used at will to personalize the system overall response curve, customizing it for different musical genres POP / ROCK / CLASSIC and JAZZ or depending on the passengers inside the car, in combination with the setting of time delays, using different memory presets.
The user can avail of:
i. 4 PEQ (FIR) + 1 PEQ (IIR, up to 100Hz) + 1 high-Shelf (FIR)
ii. Selection of slow/ fast roll settings of DAC converters to change the output filter settings of the bit One HD Virtuoso’s DAC device (Analog outputs).