The first DSP block in the DC-One’s signal flow is the stereo Hi-Pass Filter. In any sound reinforcement system, the Hi-Pass filter is crucial for maximizing the efficiency and performance of the PA system. Both analog and digital audio sources can include significant sub-sonic (infra-sonic) program material and artifacts. Audio frequencies below the threshold of human hearing can still be present at the amplifier inputs, and the amplifiers and loudspeakers will do all they can to reproduce to reproduce them; at a great cost of power and efficiency.
Hi-Pass filters can set a frequency, below which, signals will be attenuated or reduced. The cut-off frequency selected for the hi-pass filter – below which the frequencies will be attenuated - will vary depending on the program material and connected loudspeaker system. For example, full range music can produce frequencies down to the theoretical limit of human hearing (20 Hz), some acoustic music can be limited to frequencies above 60 Hz, and voice-only reproduction is limited to much higher frequencies. Hi-pass filter applications and settings will be determined by the needs of the given DC-One preset selected for the program material and sound reinforcement system.
The DC-One Hi-pass filter offers several response curves, or slopes, to suit the needs of the given application. Select the curve that best meets the needs of your particular situation:
Freq - The cut-off frequency for the Hi-Pass filter. The frequency range is from 20 Hz to 200 Hz and is adjustable in 1 Hz increments. Select the frequency setting that is appropriate for the attenuation slope selected and type of program material.
Bypass – No sub-sonic or low-frequency filtering is applied. Use this to bypass the Hi-Pass filter.
Slp - Slope or degree of attenuation.
6dB/Oct – A very gentle attenuation of frequencies below the selected cut-off frequency; good for acoustic music that is generally within known frequencies, but may drop below; without much energy.
12dB/Oct – Steeper attenuation of frequencies below the selected cut-off frequency; useful when un-expected low- frequency material may be encountered. When 12dB/Oct is selected, Q band is available - from 1.4 to 2.0.
