Music Radar / SampleRadar released 171 free feedback samples.
“For some, feedback is a curse, but SampleRadar is of the opinion that it sometimes pays to embrace its squealy charm.
Hence this collection, the sounds in which were created by running two or three chains of pedals in and out of an LEM Baby mixer/tape echo. For the guitar samples, a Danelectro Baritone was also used; the others were made simply by feeding the mixer back on itself through the pedals.”
More info and download here: http://www.musicradar.com/news/tech/sampleradar-171-free-feedback-samples-453706?cpn=RSS&source=MRNEWSTECH