I would like to sell my 412SP. There is no info regarding the SP, other that it was built in 1974. Original Sunn transducer speakers. Square cabinet. Casters on the bottom and rubber legs on the side. Parallel ports. excellent condition. No rear access panel. Velcro attached face. This was never gigged, so no tears or dings. Sounds great. It,s worth the $400 that I am asking for it. It is located in Slippery Rock, Pa. You can see photo's in the Q&A forum under brink47 412SP. Email me at plbrinker@zoominternet.net with any questions or more photo's.