  For any dg algebra $A$ we construct a closed model category structure on dg
$A$-modules such that the corresponding homotopy category is compactly
generated by dg $A$-modules that are finitely generated and free over $A$
(disregarding the differential). We prove that this closed model category is
Quillen equivalent to the category of comodules over a certain, possibly
nonconilpotent dg coalgebra, a so-called extended bar construction of $A$. This
generalises and complements certain aspects of dg Koszul duality for
associative algebras.
