We measured the linear viscoelastic properties of a series of polystyrene melts with pom-pom architecture consisting of backbones ranging from marginally to well-entangled (of molecular weight M-b), end-grafted with q unentangled branches (M-br) per backbone end. In this case, the branches relax very fast and act primarily as solvents for the backbone. Using a time-marching tube-based model, we showed that, in such a case only, the pom-pom polymer is equivalent to a blend of long (M-L approximate to M-b + 2M(br)) and short (M-S approximate to M-br) linear chains with respective proportion (M-b + 2M(br))/2(q -1)M-br.