[sdiy] modern AD/DA chips?

[Tom Wiltshire]

On 6 May 2009, at 00:15, Tom Arnold wrote:

> I dont see any combo ADC/DAC parts from them, although I've only  
> spent about
> 10 minutes so maybe I've missed them.

There's a page of Codecs, but like you say, they are intended for audio:

http://www.cirrus.com/en/products/pro/techs/T3.html

> They have some good industrial grade
> ADCs but no Industrial DACs and the error on the audio stuff is as  
> expected,
> fairly poor.  Fine for audio, but not for precision CV stuff.

How much precision do you really need? There have been plenty of  
discussions here before about the required accuracy for (for example)  
pitch CVs, and it often seems that people are struggling to achieve  
better-than-16-bit accuracy (difficult in analog design) when in fact  
12 or 14-bit would easily do the job.

Another approach would be to use two DACs with less resolution to  
create one of higher resolution. There's an example of this in the  
datasheet for the Microchip MCP4921/4922 (a cheap 12-bit single/dual  
DAC). One or two synths of old have used the same trick to get  
sufficient accuracy from the dodgy DACs they had available back then.

HTH,
Tom