GSP TRACON Controller reported an aircraft flew below an MVA.

Narrative

Relieved previous controller; and sat down to immediately begin making multiple transmissions. Aircraft X had been turned on a downwind heading for the sequence behind another commercial air carrier prior to the previous controller being relieved. Upon sitting down; frequency congestion became an issue. The lead aircraft in the sequence had been cleared for the visual approach; and as I looked to point out the traffic for Aircraft X to follow; I noticed they were already in an obstruction MVA (2;800 ft) at 2;500 ft. Aircraft X's course was about 3 miles Northwest of the antenna. At no time was the jet pointed at the antenna; but did lose lateral separation from the antenna. Upon realizing that the Aircraft X was within the required lateral spacing for an obstruction; the aircraft saw the interval traffic; was told to follow the traffic; turned away from the obstruction; and was cleared for the visual approach.Controller preference in that area of the base turn is usually taught to descend aircraft to 3;000 ft; or 2;800 ft at the lowest due to that obstruction. Better controller judgment of using 2;800 ft; or 3;000 ft; especially during a controller relief while combined with more than one position.