I have a 4x10 with the VOL-FP (front panel knob, can adjust volume). How is the volume control is implemented internally?
I assume that this is done in the digital domain... is there dithering or other means used to reduce distortion from bit truncation? There is lots of info about how "bad" digital volume control can be when it is not implemented with care, so I would like to be informed about this for the 4x10 implementation.
Before posting here I looked around but haven't been able to find any info on this elsewhere...
-Charlie
I assume that this is done in the digital domain... is there dithering or other means used to reduce distortion from bit truncation? There is lots of info about how "bad" digital volume control can be when it is not implemented with care, so I would like to be informed about this for the 4x10 implementation.
Before posting here I looked around but haven't been able to find any info on this elsewhere...
-Charlie
@ Charlie,
Sorry for the delay, many places to answer emails/forum posts these days.. Sometime we miss some!
In answer to your question, the volume control algorithm is out of our control here (done as a block algorithm under SigmaDSP where we don't have access to the code unlike our Sharc OpenDRC platform) so we can't give much detail on how they did that implementation unfortunately.
With this said, dither should be applied mostly in 16bit system. That's where really that was required. In a 28bit or 32bit system, it's less of an issue since you'd be limited by the DAC performance before the DSP distortion (reason for introducing dither). We haven't been able to see that distortion unless you go down to very low level (i.e. -80dB) where at this point, if you run the DSP in this configuration, you shouldn't be worrying about Dither, you should be worrying about gain structure!
Devteam
Sorry for the delay, many places to answer emails/forum posts these days.. Sometime we miss some!
In answer to your question, the volume control algorithm is out of our control here (done as a block algorithm under SigmaDSP where we don't have access to the code unlike our Sharc OpenDRC platform) so we can't give much detail on how they did that implementation unfortunately.
With this said, dither should be applied mostly in 16bit system. That's where really that was required. In a 28bit or 32bit system, it's less of an issue since you'd be limited by the DAC performance before the DSP distortion (reason for introducing dither). We haven't been able to see that distortion unless you go down to very low level (i.e. -80dB) where at this point, if you run the DSP in this configuration, you shouldn't be worrying about Dither, you should be worrying about gain structure!
Devteam
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