12-Jan-2016, 06:54
Hi, Pleyel.
Indeed, maybe the explanation glossed over important parts and oversimplified some others.
So, to add some more detail, some base facts:
Most DACs accept 32bit input easily. So if you upconvert your 16bit or 24bit stream into 32bit, you have at least 8-16bits for volume control.
S/PDIF is limited to 24bit samples, so that's the max your DAC will get.
Most power-amps add a flat 36dB to the signal fed into them (set by the internal feedback ratio). On some, you can change the resistor value in the feedback loop to attentuate this.
Most of the time you attenuate in the preamp and then amplify in the power-amp.
Phantom has a different structure, applying complex DSP to the signal before playback, and controlling the internal power-amp directly. This means that the more accurate signal you provide it, the more accurate the results of it's internal math calculations. The maximal bit-depth you can provide it over S/PDIF is 24bit. If you attenuate beforehand, even with proper dither, you are still reducing the bit-depth, which may affect the accuracy of the resulting math calculations and audio fidelity. Playing a 24bit source stream, there is no way around losing fidelity, as the Phantom DSP never sees the original bits. Playing 16bit source stream on a proper upconverting and dithering/noise-shaping playback device , you indeed have the 8bits for volume control and there is no harm done, as no information is lost.
Regarding protocols, still seeking participants with a couple Phantoms + Dialog that are willing to run Wireshark and capture some of the communications between them. Please PM if you can help.
Indeed, maybe the explanation glossed over important parts and oversimplified some others.
So, to add some more detail, some base facts:
Most DACs accept 32bit input easily. So if you upconvert your 16bit or 24bit stream into 32bit, you have at least 8-16bits for volume control.
S/PDIF is limited to 24bit samples, so that's the max your DAC will get.
Most power-amps add a flat 36dB to the signal fed into them (set by the internal feedback ratio). On some, you can change the resistor value in the feedback loop to attentuate this.
Most of the time you attenuate in the preamp and then amplify in the power-amp.
Phantom has a different structure, applying complex DSP to the signal before playback, and controlling the internal power-amp directly. This means that the more accurate signal you provide it, the more accurate the results of it's internal math calculations. The maximal bit-depth you can provide it over S/PDIF is 24bit. If you attenuate beforehand, even with proper dither, you are still reducing the bit-depth, which may affect the accuracy of the resulting math calculations and audio fidelity. Playing a 24bit source stream, there is no way around losing fidelity, as the Phantom DSP never sees the original bits. Playing 16bit source stream on a proper upconverting and dithering/noise-shaping playback device , you indeed have the 8bits for volume control and there is no harm done, as no information is lost.
Regarding protocols, still seeking participants with a couple Phantoms + Dialog that are willing to run Wireshark and capture some of the communications between them. Please PM if you can help.
