Files here are usually FLAC or wave, 96 KHz/24-bit, mono, except for synthetic effects and live stereo recordings (which are not necessarily samples for synths).
Note that all files are free for non-commercial use only. Any commercial/profit use requires a licence. Send a message for that or use the website contact form. Some samplers can also be bought directly at the website. In other words, if you intend to use a sound in a freeware game, all you have to do is include a link to http://www.solarstudios.net/ in credits and mention the original sound filename. If you plan using a sound on TV, radio, in a commercial game, etc., please contact a request a commercial licence first.
Some information on recording techniques...
Microphone cable is hand-woven silver-plated copper twisted pair with shielding. Line cables are much the same, except straight wiring. This is what accounts for the liveliness, pretty much.
The microphones themselves are usually: MXL 440, MXL 441, AKG Perception 170, AKG D-40, Rode NT5-MP, Shure SV100.
The sound interface is Roland UA-1G, based on AK4556 DAC/ADC.
All recording is done in 96 KHz/24-bit, in a room with acoustical treatment and minimal echoes (there are some "live" areas though and there's gear).
Note: the samples here are usually experimental takes and beta/pre-release versions. Final versions will be included in a commercial drumkit/percussion sampler, Solar Battery, which is a full GM/GS drumkit.