XDR (extended dynamic range)

XDR (Extended Dynamic Range)
XDR (extended 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.

This is achieved by many steps, the most prominent being:

Duplication of the cassettes from a 1" wide master loop tape mounted in a loop bin duplicator (as opposed to standard cassette duplication using a 1/2" master loop tape), resulting in clearer high frequencies, greater bass response, and less noise

Recording a short test toneburst at the beginning and end of the program material on the cassette, to detect for any loss of audio frequencies in the audio spectrum. The toneburst consists of 11 tones about .175 seconds in length, each an octave apart. 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.

Several labels such as EMI, Capitol, PolyGram, and others offered cassette releases duplicated with the XDR process.