Speaking of duplication, the process for duplicating pre-recorded reel to reel tape was a far more complex and expensive exercise than pressing an LP and another reason that the range of titles available was limited. The process involved master, slave and transfer decks and the process to cut and individually wind tapes for final packaging. The process started with a master deck running a master tape. However, the master tape was not on a reel but stored in a tape reservoir similar to that on the Marconi-Stille recorder.
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The master was spliced end to end to create a loop which would only be run forward. The master tapes were mostly duplicated direct from studio master tapes but sometimes they were created from an LP! The slave decks were loaded with blank tape 6000-8000 feet in length which was recorded and re-reeled onto a precision reusable reel. It was then mounted onto transfer machines that would wind the tape onto individual "consumer" reels that the operators would mount into the machine one-at-a-time. To add a modicum of automation to this process, there were pilot tones added to the bulk recorded tape which would signal the transfer deck to stop at the end of the recording. The machine would transfer the recorded tape until it encountered the pilot tones, then stop and back up until they were found again. The operator would then splice on a length of leader, splice a leader onto the start of the next recording, change the output reel and go again. These machines ran at very high speeds and used pneumatic disc brakes to stop the reels. The individual reel of tape was then labelled, boxed, and packed. A QC team would sample the duplicates on a random basis, listening to the entire tape to detect defects which would indicate problems with the slave recorders or transfer decks.
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It’s no wonder that the cassette became the dominant tape format. Running an open reel duplication plant would have been a maintenance nightmare as well as being highly labour intensive. Cassette duplication, by contrast, was infinitely simpler.