Cross-talk Between Spiral Grooves


Cross-talk between spiral grooves1 is a condition when a groove on a disc is modulated by its neighboring groove. Pre-echo2 is a condition when a groove on a disc is modulated by its subsequently played groove3 and post-echo4 is when it is modulated by it’s preceding groove.

This manifests as faint program material one revolution before or after intended. The slower the disc playback speed the more length of echo will be noticed; this means the cross-talk on a 16 2/3 rpm disc will be longest and cross-talk will be shortest on 78 rpm discs. This artifact is usually low in level compared to program material since it is a byproduct of heavy modulation of the neighboring groove. With expert disc cutting this artifact should be absent or of very minimal in level. This condition generally is most apparent during silences before a band begins.

Can it be fixed?

This is fundamentally a carrier artifact and should be handled accordingly when capturing the original object.

The most audible grooved disc pre-echo (a section of silence before a band begins) can be corrected in post production. Often the pre-echo is markedly more on the shared groove wall with the cut creating the pre-echo. The opposite wall could be copied over or silence added from another portion of the disc. Care should be taken that if it is a stereo recording the stereo image’s character is not compromised by copying the other channel (normally left channel).

Example(s)

Listen to Grooved Disc Pre-echo on Soundcloud

References

1. International Electrotechnical Committee, IEC 806-14-64, 1998.
2. International Electrotechnical Committee, IEC 806-14-65, 1998.
3. L. Boden, Basic Disc Mastering (2nd ed.), (Cincinnati: Larry Boden, 2013), 41.
4. International Electrotechnical Committee, IEC 806-14-66, 1998.

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