Calhoun averaged 5.3 points while playing all 25 games in his only season with the Seminoles, who reached the Sweet 16 in the NCAA tournament before losing to top-seeded Michigan 76-58. Calhoun has two years of eligibility remaining.
The signing of Calhoun, announced Wednesday, was the latest since Adams replaced Chris Beard, who left for rival Texas after leading the Red Raiders to the 2019 NCAA championship game during his five seasons.
Other transfers joining Calhoun are Chandler Jacobs, the career scoring leader at Dallas Baptist, and Kaelen "K.J." Allen of East Los Angeles College.
Several Texas Tech players have left the program or announced their likely departures since Beard went to his alma mater after a second-round loss in the NCAAs. Adams was a key member of Beard's staff for all five of his seasons at Tech.
Junior guard Kyler Edwards entered his name in the NCAA transfer portal. Sophomore forward Terrence Shannon Jr. plans to explore the draft without hiring an agent, making him eligible to return.