Hi all -
Maybe someone can help me with this question. I have a Mark Levinson 5101 SACD/CD/Streamer and am wondering the following:
I know that the PCM filters alter the way the DAC processes my standard CD’s, but do these filters apply to SACDs or when I stream Tidal?
Also, this device has a DAC SACD lowpass filter that can be set to: 47, 50, 60, or 70 khz.
Thanks in advance…
The PCM filters will be used when performing PCM playback, whether that’s from CD or via Tidal etc. The reason they exist is that CD’s low-sample-rate PCM data only encodes frequencies up to 22.05kHz. We need to try and figure out a continuous path between each sample which minimises the amount of sound created above that frequency – all of which would be noise. Because we want to keep the audio up to about 20kHz but don’t want anything much higher than that, we need really steep filters which have side-effects such as roll-off and frequency-dependent phase shift.
SACD data, taken at face value, encodes a signal which includes a great deal of ultrasonic noise precisely described all the way up to 1.4112MHz. However that noise floor doesn’t really start to lift until somewhere around 60kHz, a good way above our nominal 20kHz human hearing limit. So DSD filters can start higher (you are given options from 47 to 60kHz on your player) and be gentler than PCM ones, greatly reducing the roll-off and phase distortion in audible frequencies.
This filter issue is the whole reason why “high res” digital can be beneficial. But you only get the full benefit if the entire recording, processing and playback chain avoids using the “brick wall” filters around 22kHz which CD quality (effectively) requires.
I have played with the filters on my Gryphon Ethos DAC. I can hear the subtle differences between the seven PCM filters and have two favorites. But the three DSD filters not so much. 50hz, 60hz, and 70hz. It doesn’t trouble me too much.
Thanks for the information, so are the PCM filters enabled when playing an SACD or Tidal?
PCM filters will be used any time you’re playing PCM. That means from CD, CD layer of SACD, Tidal or other streaming sources. The vast majority of digital audio is delivered in PCM form.
If you are listening to the DSD layer of an SACD, or are streaming DSD files from an external source (I’ve no idea if your device supports that, but many DACs do) then you will be using the gentler DSD filters instead of the PCM filters.