Meinrad Liebert criticized the IEC for failing to impose strict standards: the organization simply followed the market, periodically adapting its set of reference tapes to arbitrarily chosen "industry averages". Unchecked spread of incompatible cassettes made traditional fixed-bias decks almost unusable for recording; this, according to Liebert, explained sudden demand for calibration features that did not exist in the 1970s. The Revox design team opted for automated calibration, although then-prevailing manual calibration was not only cheaper, but more robust as well. A human operator has an inherent advantage in handling inevitable dropouts, transients and slow fluctuations of the tape's sensitivity; fully automatic calibration often failed to handle random irregularities and could generate different "optimum points" for the same tape.
