While driving away from a flea market after looking all morning for KLH I thought I wouldn't find anything, then I spotted a late arrival, pair of model six's in mint condition, blond finish, all plywood cabinet, serial numbers 684 & 711 What years did KLH use this 12-ply plywood. These must be first year if not first week speakers with such low serial numbers. I'm interested in any info on early KLH. When did production start on the model six?