Does it say just "Sovereign" on the headstock or does it say "Harmony Sovereign"?
"Sovereign was Oscar Schmidt's deluxe brand. The Sovereign line included both six and twelve string guitars as well as banjos and mandolins. Sovereign was originally a brand of the Oscar Schmidt Company of New Jersey and used on guitars, banjos and mandolins. In the late 1930s Harmony bought a number of brands from Oscar Schmidt including Stella and Sovereign. Sovereign was no longer used as a brand from this point but Harmony did use it as a model name."
Either way, it would be very helpful to see some pictures.