 Following Isberg 's departure , Åkerfeldt took over vocal duties and he , Lindgren , and Nordin spent the next year writing and rehearsing new material . The group began to rely less on the blast beats and aggression typical of death metal , and incorporated acoustic guitars and guitar harmonies into their music ; developing the core sound of Opeth . Bassist Guteklint was dismissed by the band after they signed their first record deal with Candlelight Records in 1994 . Opeth initially employed former member DeFarfalla as a session bassist for their demo recordings , and he went on to join on a full @-@ time basis following the release of Opeth 's debut album , " Orchid " , in 1995 . 
