It's clear that Orfeus violin bass is a copy of the infamous "Beatle" Hofner. There was always a big demand for "Beatle" basses and it's surprising how many companies missed the opportunity to release their own copy. Bulgarian Orfeus was already there in the beginning of the seventies (we don't have the exact information about when they started making those "violins").
The sound: no sustain, no lows under 90-125HZ, a very "vintage" sound, mainly low-mids. Some people like it - an opposite from Jazz bass. cheesyguitars