Playback Equalization
Playback equalization identifies the standard frequency-correction curves an open-reel machine can apply when reproducing tape.
Recording and playback equalization work together to restore the intended frequency balance. The appropriate curve depends on how the tape was recorded and its speed. A fixed-curve machine offers one alignment; a switchable machine can support several stated choices.
Playback Equalization — Reel-to-Reel
NAB, also called IEC2, and IEC/CCIR, also called IEC1, are distinct playback equalizations. Other named arrangements include AES at 30 inches per second and NAGRAMASTER. A tape reproduced with the wrong curve can have an incorrect tonal balance even when its speed and track layout match.
Compare the playback curves supported at the required speed. A recording-only EQ option does not establish the same playback capability. IEC, CCIR and DIN labels can refer to the same listed family rather than three separate choices. Tone controls, noise reduction and bias calibration do not substitute for the required playback equalization.