The Ovation 1657 Anniversary has a bizarre story: designed in 1977 to celebrate the 10th anniversary of the company, was in fact put for sale in 1979 and remained available until late 1982 (the last examples received the new Kaman bar so they lack the elegant carved trussrod cover).
I love the Anniversary for the herringbone trim, the different rosette, the fine neck inlays, the carved bridge and trussrod cover. In my opinion is one of the best early Ovation projects. See the original brochure and an interesting thread on the Ovation Fan Club forum.
This one is a fantastic looking (and smelling!) guitar in a rare natural finish and unbelievable mint condition. Bought in August 2014 thanks to Kevin Grant, who shared the eBay sale on The Ovation Instruments Collectors Board.
When I received the guitar it produced a somehow weak, rubbery sound, but I noticed that the trussrod was fully loose and the neck had a significant bow at the body joint. I started tightening the trussrod half turn per day until the neck went back to a perfect position. Then I shimmed the bridge to obtain a correct action and stringed the guitar with a set of Martin Phosphor Bronze light gauge. Both the action and the sound changed dramatically: now the 1657 plays like an electric and sounds awesome, producing a good volume and a persistent, sparkling tone, with solid basses and a pleasant twang. I consider it the best playing and sounding wood top Ovation that I had over the years.