Home Digital Drive

Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it.

[ Follow Ups ] Thread: [ Display  All  Email ] [ Digital Drive ]
[ Alert Moderator ]

Re: Defining upsampling.


Once one is clear about why one is changing the samplerate there is no cause for confusion.
The function of the SAA7220 and its descendants is trade complexity in the analogue domain for complexity in the digital domain and in so doing easing the design of the analogue filter at the output of the D/A converter ic. It does this by increasing the sample rate thus pushing the aliased images further up the spectrum. The key point wth thse devices is that the ratio is fixed. You may have a selection of ratios i.e. 2x,4x or 8x etc but these ratios are set in stone and the coefficients for these ratios are set and stored and do not have to be calculated at any point. In effect changing the sample rate is simply the means by which it accomplishes its objective.
For the AD1890 and it descendants the changing of the sample rate is the objective. It has to support arbitrary sample rates and possibly even dynamically varying sample rates. Precalculation of the coefficients is simply not an option. Now it is possible to have a sample rate converter based on the same techniques as a digital oversampling filter but it will be very limited and it certainly won't be asychronous like the AD1890. The AD1890 and its descendants operate on a very different basis in order to support what they do and are in no way the same as oversampling digital filters.

ray.

This post is made possible by the generous support of people like you and our sponsors:
  Sonic Craft  

Follow Ups Full Thread
Follow Ups
You can not post to an archived thread.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]