This is a bass drum sound :
http://audioappzorgtypeb.51.net/temp/7.mp3
It is changed from a snare drum sound :
http://audioappzorgtypeb.51.net/temp/1.mp3
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the whole process are :
a snare drum :
http://audioappzorgtypeb.51.net/temp/1.mp3
after pitch down ...
