BMB DEP- 3000K Digital Echo Processor Key Karaoke Mixing Control MADE IN JAPAN. BMB DEP-3000K Karaoke Digital Echo Processor. Up for sell is a BMB DEP-3000K Professional Karaoke Mixer with Digital Echo Processor w/ Key Controller, Made in Japan. This is the best karaoke sound mixer from “BMB”. It offers superior sound quality in singing karaoke. And this mixer is very hard to get at nowadays.