This blog is the first in a series on PGGB.
The argument put forth from those who remain skeptical about the benefits of upsampling is that filtering inside a DAC needs only to be as good as the antialiasing filtering used in the recording ADC. The belief is that more elaborate filtering cannot extract more detail or find transparency where none existed. Hence, the claim is that a simple filter with a good analog section is the best approach. The allure of NOS or R2R DACs (which do minimal upsampling) or even vinyl playback (which bypasses it altogether) clearly demonstrates this sentiment.
Regardless, DAC designers have sought better sound and Rob Watts' designs for Chord Electronics emerged to demonstrate that more information does exist in digital recordings: in the minute reverberations of instruments and voices that extended over many seconds. This is real information - not false euphonics - and an ultra long windowed sinc filter at high precision brings it out. Increasing the width of the filter (more taps), improving precision and lowering the noise floor reveals even more depth, layering and transparency. So, for better sound, it seems a worthwhile goal to pursue a theoretically perfect sinc filter - and this encouraged the development of PGGB.
PGGB's software implementation is uncompromised by hardware limitations of a real-time DAC and this makes it possible to achieve the absolute best signal reconstruction:
- PGGB uses the maximum possible number of taps for each track - essentially using all input samples to compute each output sample
- PGGB uses the highest possible computation precision - well in excess of the normal 64-bit floating point
- PGGB noise shaping maintains the total frequency spectrum of the original and retain all the input sample values
- PGGB does not use windowing, so the sinc filter is not compromised, resulting in maximum transparency with a natural & full bodied sound
This ensures the best possible estimate of the original analog signal without aliasing nor any digital artifacts. PGGB processing does not add any noise of its own so the final output is devoid of reconstruction uncertainty.
PGGB runs on Windows, MacOS or Linux to upsample source music files of any format. It's recommended to upsample to 16fS (705.6/768kHz) at noise-shaped 24 or 32 bits. PGGB files present best on DACs with an analog section that resolves the full frequency signal.
The next installment will talk about configuring a system to run PGGB at highest performance and quality.