Setting Input High-Pass Filters - Sound Devices 664 User Manual

User Guide
Not all types of sources are available for each channel:
i
nput
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
Channel 6
4. Slide the PFL switch to the left again to return to the Main screen.

Setting Input High-Pass Filters

Each input features a high-pass filter (HPF), which are useful for removing
excess low frequency energy from audio signals, such as wind noise. For
more audio applications, engaging high-pass filter is beneficial, because audio
information below 100 Hz is rarely used, especially for speech reproduction.
The filter is off by default but may be adjusted from 80 Hz to 240 Hz in 10 Hz
increments on inputs 1-6. For inputs 7-12, HPF may be turned off or set to
150 Hz.
To adjust HPF on inputs 1-6:
Turn the HPF control associated with the input.
X
To adjust HPF on inputs 7-12:
1. Access the Input Settings screen for the input to be adjusted.
2. Push the Select encoder if necessary. The HPF label will appear outlined in
white to indicate adjustment.
3. Turn the Select encoder to adjust the value. Options include: Off or 150 Hz.
The 664's HPF circuit features an adjustable corner (-3 dB) frequency over a
range from 80 to 240 Hz. Below 80 Hz, the filter's slope is 12 dB/octave. At
higher corner frequency settings, the slope is 6 dB/octave. The purpose for this
compound slope is to give additional roll-off at the 80 Hz setting to reduce wind
noise and low frequency rumble. The higher settings may be used to counteract
the proximity effect of directional microphones where a more gentle slope is
preferred.
The 664's HPF circuit is unique because of its placement before any electronic
amplification. Most mixers' HPF circuits are placed after the microphone
preamplifier, such that all of the low-frequency signals get amplified. By virtue
32
t
ypes
OFF, MIC, MIC-PH, LINE, LINE PH, AES 42, AES 3
OFF, MIC, MIC-PH, LINE, LINE PH
AES 42, AES 3 is conditionally available only if Channel 1 is already set
i
to AES 42 or AES 3
OFF, MIC, MIC-PH, LINE, LINE PH
OFF, MIC, MIC-PH, LINE, LINE PH
OFF, MIC, MIC-PH, LINE, LINE PH
AES 42, AES 3 is conditionally available only if Channel 6 is already set
i
to AES 42 or AES 3
OFF, MIC, MIC-PH, LINE, LINE PH, AES 42, AES 3