Re: [SlimDevices: Audiophiles] External DAC on Transporter: best output option
drmatt wrote: > I was assuming the volume was operated similar to Squeezebox, i.e. by > modifying the input stream to the DAC and using its output as-is. Is > that not what you're referring to here? I believe that's how the > transporter works. > That is what I am referring to. There are two separate noise mechanisms at work here. On one hand you have the noise floor of the analog buffer and output stages (that will be just the same independent of whether the volume control is digital or analog, so that is why I wasn't discussing that part, and on the other hand quantization noise that is dependent on the resolution/bit depth of the DAC. The effect of the volume control on that depends on the number of bits used internally to calculate the scaling (normally 32 or more bits), and number of bits in the output stage once you get down to levels when that starts to matter (as I wrote, about 10 bits attenuation with a 24-bit output stage). "To try to judge the real from the false will always be hard. In this fast-growing art of 'high fidelity' the quackery will bear a solid gilt edge that will fool many people" - Paul W Klipsch, 1953 Julf's Profile: http://forums.slimdevices.com/member.php?userid=42050 View this thread: http://forums.slimdevices.com/showthread.php?t=106519 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] External DAC on Transporter: best output option
Julf wrote: > Yes. No. Maybe. But mostly No. Digital volume control, by definition, is > never "bit perfect" - any attenuation in the digital domain changes the > bits. But likewise any volume change in the analog domain changes the > signal voltage, and normally decreases signal-to-noise ratio. Thus what > you should look at is SNR, both for analog and for digital. The SNR for > typical commercial source material is around 13-14 bits, so if you have > a 24-bit volume control, you can attenuate by 10 bits before you start > decreasing the real SNR. With a 32-bit volume control (typical of modern > DACs) you have 18 bits of attenuation before reducing SNR. > > A completely different matter is the fact that if you get your gain > structure right, the decrease in SNR doesn't matter - if something is > too quiet to hear, it is too quiet to hear, no matter what the volume > setting. Hi Julf! If I'm getting your drift, this implies that if I don't use the bypass on my Mytek, I should select the digital as opposed to the analogue volume control. This is relevant anyway because the volume control is always in circuit for the headphone output(s)... Dave :) Golden Earring's Profile: http://forums.slimdevices.com/member.php?userid=66646 View this thread: http://forums.slimdevices.com/showthread.php?t=106519 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
