The torque applied by the supply reel motor to keep the tape from freely spilling off the supply reel, and to maintain good tape-to-head contact.
"I received my order of the 3 CDs yesterday. I'm very happy with the way they sound. The strings (high notes) are nice and sharp again. That I'm very happy about. Thanks for doing a good fast job! It feels good to be able to have some favorite hard-to-find songs on a CD finally. You never know, one day they may stop making turntables ..."