[sdiy] Novation peak NCOs

[rsdio at audiobanshee.com]

On Apr 21, 2017, at 11:51 AM, Gordonjcp <gordonjcp at gjcp.net> wrote:
> On Fri, Apr 21, 2017 at 07:49:21AM -0700, rsdio at audiobanshee.com wrote:
>> I'm not sure whether my question is answered in this long thread, but what is the bit depth at 24 MHz?
>> 
>> The reason I ask is that SACD runs at 2.8224 MHz, but it's only running 1 bit sampling. By the time SACD is converted to something we can listen to, it's equivalent to 20-bit at something more than 40 kHz. So, before we all go converting the Nyquist frequency for the claimed 24 MHz sampling rate, it would be helpful to know the bit depth. I've designed with DAC chips that are rated to 125 MHz, but that one is only 14-bit.
> 
> ... which is two bits more than you need for broadcast-quality audio.

I didn’t mean to imply that we “need” more than 20-bit or even 12-bit; I just wanted to point out that 1-bit @ 24 MHz isn’t the same thing as 24-bit unless you drop several MHz in terms of Nyquist.

By the way, 12-bit is acceptable in a properly mastered and dithered signal that was originally processed at a higher rate, but I suspect that the quality of sound of a 12-bit DSP system would be noticeably inferior whether you’re interested in broadcast quality or less.

Brian