[sdiy] How to measure 1-bit DAC performance?

[Tom Wiltshire]

On 25 Apr 2017, at 18:19, Roman <modular at go2.pl> wrote:

> 1% accurate multimeter sounds like $3 meter bought at grocery store. I'm sure your unit does better.
> But anyway, you need linearity more than absolute precision. So don't care if it shows 5V while in reality it's 4.9V, it's linearity that matters, and usually all DMM have good enough linearity for 12 bits.

Ok, that sounds positive. I'll give it a try.

> I'll save for myself the obvious comment like "get better DMM".

Until now, I didn't need to. Mostly I don't care whether 9V is 9V or 8.9V. Either way, I know there's no short on my stomp box power supply (for example). Most testing I do with a multimeter is like that; "Is this 10K? 9.98? Yes, it's a 10K", "Is this 5V regulator working? 5.1V? Yes, it's working" etc etc. 1% would be good enough 99% of the time. It must be similar for you.
Only now am I hitting the limit…and once I've done this, I'll be back to the usual stuff.

> So what's left are the AC analysis using line audio input in your computer and audio analysis software that you can find on the web like ARTA or TrueRTA or many others. This should be able to measure way better than 12-bit. It's just you have to write sine generating firmware for your PIC just for the tests.

I'll probably be doing that anyway, so that's no problem.

Thanks for your help, Roman.

Tom