07-19-2020, 02:03 PM
1) re EQ. in basic terms, how does “off” differ to “flat” curve?
- Off removes the EQ plugin from the DSP chain.
- On/Flat inserts it in the chain and even if the Flat curve results in no amplitude change in the frequency bands the plugin IIRC always zero-pads the bit depth to 32 bit word length. You will also see the bit-depth being automatically zero-padded to 32-bit for any audio device that only accepts 32-bit word length. Its most common in USB DAC's with high speed USB chip sets.
2) when EQ off, my output rate stays same as decoded rate i.e. 16bit. When EQ on, output rate jumps to 32 bit and I have no idea why.
- See #1
3) Allo Boss uses Burr Brown chip. I am given 4 options under ‘chip/device”options and have no idea what any of these mean.
- Chip options are described in the data sheet for the chip. They are only available in moOde if the device driver for the chip exposes them to ALSA and it makes sense to code for them. This is the case for Burr Brown PCM and TAS 5xxx chips.
- The Oversampling filters also called Interpolation filters perform necessary noise removal in the Nyquist band. Each filter does it differently. For listeners with super hearing they each might result in very subtle differences on sound characteristics.
If you are interested, these links can help you learn about the PCM5122 chip options and interpolation/filtering.
https://www.ti.com/lit/ds/symlink/pcm512...52FPCM5122
https://dspguru.com/dsp/faqs/multirate/interpolation/
- Off removes the EQ plugin from the DSP chain.
- On/Flat inserts it in the chain and even if the Flat curve results in no amplitude change in the frequency bands the plugin IIRC always zero-pads the bit depth to 32 bit word length. You will also see the bit-depth being automatically zero-padded to 32-bit for any audio device that only accepts 32-bit word length. Its most common in USB DAC's with high speed USB chip sets.
2) when EQ off, my output rate stays same as decoded rate i.e. 16bit. When EQ on, output rate jumps to 32 bit and I have no idea why.
- See #1
3) Allo Boss uses Burr Brown chip. I am given 4 options under ‘chip/device”options and have no idea what any of these mean.
- Chip options are described in the data sheet for the chip. They are only available in moOde if the device driver for the chip exposes them to ALSA and it makes sense to code for them. This is the case for Burr Brown PCM and TAS 5xxx chips.
- The Oversampling filters also called Interpolation filters perform necessary noise removal in the Nyquist band. Each filter does it differently. For listeners with super hearing they each might result in very subtle differences on sound characteristics.
If you are interested, these links can help you learn about the PCM5122 chip options and interpolation/filtering.
https://www.ti.com/lit/ds/symlink/pcm512...52FPCM5122
https://dspguru.com/dsp/faqs/multirate/interpolation/
