R2R DAC -view picture in the end of article. Usa same principle to build an 8 Bit R2R DAC from D0 to D7
Some intial test sounds out of a Uno mini Dub synth. The file was recorded , unfiltered ( 0 to 5V) and lined out of a guitar amp in clean mode. - Some noise was introduced by the guitar amd as well.
Next step of project is to AC couple signal also with a suitable RC filter, decoupling capacitors and prepare the rest of line out for use with sound gear.
The limitations of the ATMega328 are big compared to the DUE for this kind of project, but good enough to get some interesting sounds, plus it can also double as a dub siren . Sr @ 16kHz-8Bit Dac
You can download /preview it in mp3 here
a 6 bit R2R Dac