Hello, I am a MIDIBOX user and am selling a bunch of fully tested 6581 chips. You can see them on eBay here: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270326213902 I tried them all out on my MIDIBOX to make sure all oscillators are sounding and that the chip sounds good. A few didn't make the cut and are being tossed. Enjoy! Modularland http://modularland.com