"World's first high-speed 1-7/8 ips tape duplicator has Roberts world's first 1-7/8 ips HIFI tape as its first production run"

"Magnetic Tape Duplicators, Hollywood, pioneers in tape processing and first in the field with commercial duplication of four track tapes have another first. A revolutionary new biasing system has been developed which operates from a central master unit feeding six banks of duplicators. Bias current at radio frequency ...is mixed with audio signals ... and fed to the duplicator slave units

"Tapes are duplicated at 30 ips with the master tape running at 120 ips. (1-7/8 ips)tapes are therefore duplicated at a 16:1 ratio. Frequency response at 10 KHz is down no more than 2 dB.

"Its design and construction is the property of MTD and no similar units will be made for any other duplicator.

 from a MTD press release. The master tape must have been on 14 inch reels for this to be possible. The only audio cassette format at this time was the 3M Revere type which used a 3/16" tape width so that the loaded shell mechanism would be similar in size to the standard 7" tape reel. This was replaced later by the smaller Phillips type mechanism of today, hence the designation "compact" cassette.

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