Blechturmstudios releases BTS FilterBox v1.0 newseffect plugins Jan 22, 2008 0 Blechturmstudios has released BTS Filter Box, a small freeware stereo filter plug-in for Windows PC. BTS Filter Box features Filter types: Low Pass, High Pass, Band Pass, Band Reject, Peak. Modes: 12 dB, 24 dB, 36 dB. Modulation: input -> cutoff frequency. Visit Blechturmstudios for more information and a link to download BTS Filter Box.