[sdiy] Audio Codec Question

[rsdio at audiobanshee.com]

Hi Tim,

If you want DC-coupling, you’ll probably have to give up 24-bit audio. Of the various technologies available for ADC - flash, successive-approximation, sigma-delta, et cetera - the only technologies used for 24-bit are not DC coupled. At least that’s my understanding of the technology. These chips tend to have automatic DC calibration because of the way they work internally.

However, it’s fairly easy to find 16-bit and even 20-bit ADC chips that are DC-coupled. They simply aren’t using sigma-delta technology. Instead, they typically have an on-board voltage reference or an input pin for an external voltage reference (or both!) and compare all inputs as DC signals against the reference.

It’s a tough choice, because the Asahi-Kasei converters are the best designs! However, if you need to support CV or other DC-coupled signals without any offset, you’ll need to trade off.

Brian Willoughby
Sound Consulting


On May 8, 2018, at 5:53 PM, Tim Ressel <timr at circuitabbey.com> wrote:
> Hi,
> 
> Does anyone know of an audio codec that does not have DC blocking on the ADC inputs? Iwas going to use the AK5720 but sadly it has DC blocking on the inputs.
> 
> Thanks!
> 
> -- 
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com