This　paper　proposes　a　novel　method　for　converting　multichannel　signals　of　an　original　system　into　that　of　an　alternative　system.　Based　on　spherical　harmonics　expansion,　we　present　a　conversion　formulation　to　derive　matching　equation　which　explains　a　direct　relationship　between　weighting　matrix　and　positions　of　loudspeakers　located　on　both　systems.　The　solution　of　matching　equation　can　be　found　from　matrix　inverse　where　under-determined　problem　might　exist.　To　solve　this　problem,　l(1)-norm　minimization　is　proposed　for　finding　a　minimum　number　constraint　of　the　active　loudspeakers.　Simulations　confirm　that　the　proposed　method　is　able　to　reconstruct　original　sound　field　within　a　finite　region　of　listening　and　has　better　wideband　performance　than　traditional　method.