| General > General Technical Chat |
| Why do cassettes have the tape go around a solid plastic post next to the roller |
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| dmills:
Pretty sure it is a tension thing, the diameter of the reel varies by probably 2.5:1 or so, which means that with a simple minded torque drive on the takeup spool, the tape tension would vary by about 2.5:1. When the tape reel is at minimum diameter (=maximum tension given a constant torque take up) the tape is wrapped further around that peg then it is when the reel is at maximum diameter, increasing the friction and making the tape tension around the rollers and across the front of the doings more nearly constant. This friction also damps the tendency for the thing to overshoot and spew tape when hitting the stop button after fast forward or rewind (Something that requires annoyingly complex brakes on a pro reel to reel machine). For a consumer product, a pair of plastic pegs that work well enough in the injection moulded cassette trumps a rather complicated variable tension set of brake bands and mechanical servo loop (and solenoid) in the player, especially as the brake in the player would need frequent servicing. |
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