DSD FIR filter

The DSD format is an unfiltered stream of a 1-bit SD modulator, for high-quality playback of which you need to completely filter out the entire RF noise of the modulator, otherwise it will fold back on the non-linearities of the DACs and analog stage.

Considering the non-optimal FIR filters (or lack thereof) that come with foobar2000 sacd decoder, Aplayer sacd input, weiss saracon, korg audiogate, jriver, namely, insufficient noise filtering, large filter attenuation and, as a result, poor impulse response and unknown passband ripple for these filters. As well as insufficient filtering of the DSD stream by the vast majority of D / A converters with this capability, it was decided to calculate a filter that does not have these disadvantages.

FIR filter with a minimum allowable attenuation and passband ripple of 0.00001 dB was created, which allowed us to obtain a good impulse response. For DSD64, the bandwidth (by -3 db) is 26 kHz, the attenuation at 20 kHz frequency is <0.1 dB.

Below are the spectrograms of DSD64 and DSD128, black is the filtered high-frequency noise, the original signal(red color) was recording Nidarosdomens jentekor & TrondheimSolistene - Arnesen: MAGNIFICAT 4. Et misericordia

As you can see, this filter filters only noise, and does not affect the useful signal in any (DSD64, DSD128, DSD256, DSD512) DSD stream. Since virtually all DSD noise is filtered, the stream can be converted to PCM not only to 352.8 / 176.4 kHz, but also to 88.2 kHz if required.

Now there are a lot of studios offering musical material in several options to choose from (like 24/96, 24/192, DSD64, DSD128). If the source material was recorded in DSD or DXD, then this filter will give better quality than the PCM stream created from this material, because in studios DSD (DXD) to PCM is converted using halfband filters in the majority of cases, thereby obtaining maximum bandwidth and poor impulse response + artifacts from ASRC (to 96 / 192kHz conversion).

You can download this filter by clicking on this link - S-Audio.Systems DSD filter

To use this filter in foobar2000 or Aplayer you need to unpack the content of the archive into some folder, in the player select the SACD plugin, than select Installable FIR and load this filter from the folder into which the archive was unpacked. Screenshots from foobar2000 and Aplayer are presented below:

An optimized filter was also developed that allows you to get even better sound at the price of versatility, it is possible to use it only when outputting at 352.8 / 176.4 kHz. You can download this filter by clicking on this link - S-Audio.Systems DSD short MP filter

"Directly or indirectly, all questions connected with this subject must come for decision to the ear, as the organ of hearing; and from it there can be no appeal" J.W.S. Rayleigh