Equalisation Filters, Crossover shapes

7.0SOFTWARE OPERATION

8.0SOFTWARE OPERATION

Audio Processing

VNET“ provides the following processing options:

•• Crossover filtering with frequency variable over the range 10Hz to 25kHz (and Out ) with the following alignments:

•1st order

•12dB/Octave Bessel

•12dB/Octave Butterworth

•12dB/Octave Linkwitz-Riley

•18dB/Octave Bessel

•18dB/Octave Butterworth

•24dB/Octave Bessel

•24dB/Octave Butterworth

•24dB/Octave Linkwitz-Riley

The Low band has a low-pass crossover filter, and the High band has a high-pass and a low-pass crossover filter.

•A 2nd order low-shelf filter with frequency variable over the range 10Hz to 25kHz, and boost/cut from —15 to +15dB.

•A 2nd order high-shelf filter with frequency variable over the range 10Hz to 25kHz, and boost/cut from —15 to +15dB.

•Eight bands of bell (parametric) equaliser, each band having frequency variable over the range 10Hz to 25kHz, bandwidth variable from 0.1 to 5 octaves, and boost/cut from —15 to +15dB.

•Delay adjustable up to 200ms.

•Adjustable gain from —30 to +15dB, and mute.

Equalisation Filters

The eight Bell filters (Parametric equalisation filters) may each be used to emphasise (by applying a positive Level parameter setting) or de-emphasising (by applying a negative Level parameter setting) a range of frequencies centred on the setting of the Frequency parameter, and encompassing a frequency range determined by the Bandwidth parameter setting.

The two shelving filters allow all frequencies below that of the frequency parameter (for the Low shelf) or all frequencies above that of the frequency parameter (for the high shelf) to be emphasised (by applying a positive Level parameter setting) or de-emphasised (by applying a negative Level parameter setting).

Crossover shapes

In addition to the usual Butterworth, Linkwitz-Riley and Bessel filter shapes, VNET“ processing provides access to Hardman crossover filtering. Hardman filters produce much steeper cut-off slopes for a given order than conventional crossover alignments, without any additional group delay. This allows a lower order filter to be used without sacrificing cut-off characteristics, but with smoother group delay and less severe phase penalties, giving a more natural sound. Hardman filters and also provide identical phase characteristics between adjacent bands (like Linkwitz-Riley), so the polar performance is rock steady

We also employ phase matching on our Bessel filters, so adjacent bands are in-phase throughout the crossover region.

Protection (factory optimised)

Comprehensive protection features preserve the longevity of the amplifier by continuously monitoring several critical parameters, and reducing the gain, or muting the amplifier either temporarily or permanently depending on the nature and seriousness of the fault or misuse. The amplifier will recover and restart if at all possible, but will remain shutdown if a serious fault persists (such as a permanent short circuit on the output).

Minor faults are dealt with by slowly dimming the amplifier, reducing the level to a sufficient degree and for a sufficient time that the amplifier is able to recover gracefully without any user interaction. When the fault condition has passed, the amplifier will slowly fade up to normal.

More serious faults may cause the amplifier to mute while it recovers, after which it will automatically re-energise and fade up, again without user interaction. If such a fault is found to be persistent however, the amplifier is shut down permanently, flashing its limiter indicators rapidly in unison. A power cycle by the user is then required.

Any time the amplifier is being protected, the limiter indicator will flash rapidly.

During power-up, VNET“ will keep the amplifier muted for a short time while checks are made that all is well. During this time, the Indicators will both be solidly on. The signal is then gently faded up, accompanied by rapidly flashing Indicators.