Toneburst

XDR (eXtended Dynamic Range, also known as SDR (Super Dynamic Range)) is a quality-control and duplication process for the mass-production of pre-recorded audio cassettes. It is a process designed to provide higher quality audio on pre-recorded cassettes by checking the sound quality at all stages of the tape duplication process. In this way, the dynamic range of audio recorded on an XDR-duplicated cassette can be up to 13 decibels greater.

XDR was originally developed by Capitol Records-EMI of Canada in 1982 as "SDR" (Super Dynamic Range). Capitol in the USA then adopted the system for its cassette releases that same year, renaming it "XDR".

The XDR/SDR process involves many steps, the most prominent being:

These tones are recorded on the cassette, and are read during the duplication process to detect if there is any loss of any audio information.

As well as with EMI & Capitol Records, PolyGram and other labels also offered cassette releases duplicated with the XDR process.

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