5.4.9 Capstan-less Machines and Non-linear Speeds Some early generation reel recording machines were designed to run without the control of the capstan and pinch roller, and consequently exhibit steadily increasing speed. If these tapes are played at a standard, unchanging speed, the resultant signal would decrease in pitch as the tape was replayed. To play the tape correctly the replay speed must change in the same manner as the recording speed. Some of the more recent replay machines, such as those made by Nagra or Lyrec, have incorporated a voltage driven external speed control which allows the operator to design a simple circuit with a curve that matches the speed of the original. Some of the last generation replay machines, such as the Studer A800 series, incorporated microprocessor control allowing for programmable manipulation of the speed, and others like the Lyrec Frida allowed the speed to be manipulated in the MIDI environment. However, care should be taken in assuming that the speed increase is linear. The early capstan-less machines were made cheaply and the speed varied according to the load on the reel, the speed increase is often less at the beginning or end of the tape where one or the other of the reels is full making a graph of the replay speed over time far from linear.