Thread to discuss which filters and modulators we are using in HQP and why.
The filters are described in the HQP Manual. There is a link to the Version 3.1 manual in the Signal Chain footer in Roon. The latest version of the manual, including descriptions of later filters, can be found in the HQP folder.
Geoffrey Armstrong’s KIckstart guide contains some basic information about setting up HQP.
These CA threads also contain useful information and discussion about the filters:
So far I have tried the filters described below (all upsampling Redbook local and Tidal to DSD128 into an Auralic Vega using ASDM7).
closed-form and closed-form-fast
I thought these had the biggest space/soundstage. Huge tracts of land !
Edit: Compared to poly-sinc-shrt-mp I hear some increased harshness in high frequencies with closed form. I suspect it’s because of the extra processing it requires and it might not appear with more powerful hardware.
Very intensive on the CPU, starts the fan on my BRIX. I couldn’t distinguish fast (lower CPU) from the original. These are non-apodising filters (meaning noise from the ADC process is left where it was). I understand the WTA Filter used in the Chord DAC is a closed form interpolator.
Spacious but I prefer the linear phase poly family below which seems more detailed.
poly-sinc, poly-sinc-shrt, poly-sinc-hb, poly-sinc-ext
Spacious and detailed. These all sound good, but I keep gravitating back to poly-sinc-ext.
Rock and Roll baby ! Dynamic and detailed. Poly-sinc-shrt-mp is my go to for anything driven by drums/percussion.
Edit: These filters really shine with decay. Most beautiful trailing sounds I’ve heard from my system.
Dynamic but prefer the poly-sinc-mp family.