The High Voltage SID Collection (HVSC - http://www.hvsc.c64.org) is a terrific repository for thousands of SIDs. Also, check out the Commodore Scene Database (CSDb - http://noname.c64.org/csdb), which not only has lots of SIDs, but also demos, meetup info, graphics, etc.
Shredz64
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Due to memory limitations of the C64, Shredz64 can only handle up to 10 SID files on disk. You may copy the full program with different combinations of other SIDs though.
While Shredz64 will certainly run on a C64 emulator, the commands for strumming, lifting the guitar up, and using the whammy bar are sent over the joystick pins normally used for paddles on the C64. Many emulators such as Vice do not support paddles. For the tinkerers out there, if your emulator does support paddles or you're adding support, Shredz64 recognizes the following byte values (in decimal from 0-255):
Pot X: 90 = Strum bar at rest, 21 = strum down, 47 = strum up
Pot Y: 44 Whammy Up -> 80 Whammy Down, 19 = Guitar lifted
Additionally, we've noticed timing issues during gameplay, especially if warp mode has previously been used. You may need to slightly adjust your emulator's speed settings.
It’s likely the SID uses a raster interrupt, and was designed on the opposite system as yours (E.g. you’re on an NTSC system playing a PAL SID, or visa versa). Normally Shredz64 can compensate for this, but only if the video standard is set properly in the SID file. Sometimes this video standard isn’t set, and Shredz64 doesn’t know what speed the SID is supposed to be played at. The video standard flag is at byte 77 of the SID file, bits 2-3. If it is set to 00, the video standard was unset. Manually set it and save the file and it should play properly. If the file is supposed to be a PAL file, set it to 01 - for an NTSC file, set it to 10.
While Shredz64 has the ability to use SIDs not originally included with the game, there are a few limitations. One, the SID must load into Bank 0, or the first 16K of memory - and above the $0909 (about the first 2K). So the SID must load within $0909 - $4000. Additionally, the SID must have a callable player - if the play address is $0000, it will not work. Lastly, the SID must not use PlaySID samples, which cannot be played back on an original C64. Shredz64 will take both NTSC and PAL sids though.
