[sdiy] D to A convertor for wavetable osc

[Eric Brombaugh]

jays at aracnet.com wrote:
> 
> One thing to look out for with AKM DACs is turn on thump. Some of them have a built in capacitor that can pop when it is first charged up. It can be pretty loud if you have a high gain on the DAC output or a amp with its gain turned up. On those converters they mention this is the data sheet.

The Cirrus/Crystal parts avoid the turn-on thump by slowly ramping up 
the Vq as soon as they get a clock lock. It starts out at 0V and 
linearly ramps to VDD/2 over about a 1/2 second interval - easily 
tracked out by a 20Hz DC blocking network.

If you're DC coupling them this anti-pop feature can be a bit of a 
nuisance unless you're using the parts with Vq available on a separate pin.

OTOH, unless you're cycling power frequently on your system a bit of pop 
at startup shouldn't be a major hassle. Most power amps these days have 
a power-up delay to protect your speakers anyway.

Eric