Limor Fried, aka LadyAda, has introduced Wave Shield, a way to add audio output to Arduino projects:
Adding quality audio to an electronic project is surprisingly difficult. People tend to end up either using low-quality ISD chips (you might get 8Khz sampling rate for 30seconds out of these, if you’re lucky!) or mucking around with trying [...]

LadyAda, aka Limor Fried, has a new DIY kit, the Boarduino Arduino clone.
If you’ve ever struggled to use a solderless breadboard with an Arduino, you understand how frustrating it can be! I designed this Arduino clone to solve this problem in an inexpensive DIY fashion. Kits with all parts are available in the Adafruit webshop [...]

If you haven’t checked out the x0xb0x DIY synth yet, here’s some videos to get you inspired:
x0xb0x demo

Soldering a x0xb0x

x0xb0x MODS jam

Dual x0xb0x Demo

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