The former world number one experimented with a new, bigger frame after Wimbledon, playing in clay-court tournaments in Hamburg and Gstaad.
But he was back playing with his regular Wilson racket last night as he began the defence of his Cincinnati Masters title with a 6-3 7-6 (9/7) victory over Germany's Philipp Kohlschreiber.
Federer said on www.atpworldtour.com: "I'm going to do more racket testing when I have some more time after the US Open.
"I was playing for a month with the black one, but it's a prototype. At the end, I just felt right now I feel like I need to simplify everything and just play with what I know best."
Federer has had his most difficult season for more than a decade, winning just one title in Halle and suffering a second-round defeat by Sergiy Stakhovsky at Wimbledon to end his remarkable grand slam quarter-final streak.
The bigger racket - with a 98-square-inch head rather than 90 square inch - appeared an admission he needed a fundamental change to try to recapture his old form.
But it was far from an immediate success, with Federer losing to Federico Delbonis in the semi-finals in Hamburg and then Daniel Brands at the first hurdle on home soil in Gstaad.
The 32-year-old was hampered by back problems which saw him miss last week's tournament in Montreal, and Federer is under pressure to do well in Cincinnati or risk sliding further down the rankings ahead of the year's final grand slam in two weeks' time.