Settings : Mixer
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DSD Peak Filter
For DSD projects this drop-down list offers the choice between two filtering options which will be applied to the
DSD signal before it is measured by the level meter.
This will help enable you to ensure that the DSD signal is compatible with Annex D.4 of the SACD Scarlet Book
concerning the high frequency and noise shaping.
20k
Applies a 20 kHz low pass filter to the signal, thus only the audible audio content is measured.
40k-100k
Applies a band pass filter with a frequency range of 40 kHz to 100kHz to the signal. According to Annex D.4 of the
SACD Scarlet Book the signal level in this frequency range should not exceed -20 dB.
Note: Further to Annex D.4 of the SACD Scarlet Book:
D.4 High Frequency DSD Signal + Noise Level.
The accumulated RMS signal + noise level of the DSD signal, measured after a 40 kHz Butter-
worth 30dB/Oct high pass filter and a 100 kHz Butterworth 30dB/Oct low pass filter, is maximally
equal to the RMS level of an input sinewave with a peak amplitude of -20 dB SA-CD (see D.2).
The averaging filter used to calculate the RMS level must be a first order unity gain IIR filter with a
coefficient of 1/524288 ( 2-19 ), corresponding to an IIR filter with a cutoff frequency of about
0.85 Hz.
Note: E.2 Analog Post-filter
To protect analog amplifiers and loudspeakers, it is recommended that a Super Audio CD player-
contain at its output an analog low pass filter with a cut-off frequency of maximum 50 kHz and a
slope of minimum 30 dB/Oct. For use with wide-band audio equipment, filters with a cut-off fre-
quency of over 50 kHz can be used.
Note: When releasing material at higher than 44.1 or 48 kHz sampling rate, Merging recom-
mends adding a gentle low pass filter (typically 6 to 12 dB/octave) in the range from 30 to 50 kHz
for all recordings made originally in DSD 64. The corner frequency of such low pass filters can be
doubled whenever converting from DSD 128 and even quadrupled when converting from
sources originally recorded in DSD 256 (which essentially means that even when converting
from DSD 256 to PCM at 192 kHz, there is no need to add such a filter).
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