Circa 1978? Serial #5199. U.S.A. I have not been able to find conclusive dating information. Satin finished solid mahogany body and neck with a reinforcing strip of graphite running the full length of the neck and an ebony fretboard. One tuner has been replaced, it matches all the rest exactly, other than not being stamped with the Ovation logo. The huge bridge is made of an aluminum alloy with brass saddles, and there is an odd hexagonal screw in the back of the body (directly behind the bridge.) Not sure if this is also anchoring the bridge or what it does.
This is a passive-pickup bass, unlike the majority of solidbody Ovation basses. The giant humbucker at the neck has screws to adjust the pickup volume string-by-string. The graphite insert in the neck was way ahead of Modulus Graphite and other makers using graphite as a neck stabilizer. This is a very smooth player and is capable of huge lows and tight highs dependent upon pickup selection and can produce both Fender and Gibson-type bass sounds. Currently strung with flatwounds, this bass can approximate a fretless better than any other fretted bass I own, and the bridge pickup has a great compressed "Jazz Bass" sound without the need of an outboard compressor.
All the Ovation Magnum bass series of the ‘70’s and early '80's are vastly underrated in terms of innovation, construction, and sound. The Magnum III may be the least radical of the Magnum series but is nevertheless a rare and high quality instrument with a number of unusual features. Fairly heavy at 10.6 pounds but is very well finished and has a comforting feel of durability; this bass could probably withstand the rigors of touring and gigging regularly with few worries.