Anyone using one of the Alesis M20 ADAT machines should be aware that they do not accrue head hours the same way other ADAT models have. The M20 head contacts the tape whenever the tape is loaded in the unit. Head hours are accumulated and headwear is happening if you leave a tape in the machine. Previous ADAT designs allowed the tape to stay in a machine as long as it was in “stop disengaged” mode, which pulled the tape off the head. There is no equivalent capability in the M20 at this time so it’s best to eject your tape if you are taking a break or something. Whatever you do absolutely DO NOT leave a cleaning tape in the machine! They work by “scraping” dirt off the head and will constantly grind the head away if left in.
Also, V2.03 or earlier software has a bug that causes the actual head hours to accumulate at twice the real rate. There is a software upgrade (downloadable from their Web site) that will solve this problem, but we warn not to do it until a warranty center can reset the hours first. We can divide the reading in half and correct the head hours before the upgrade is installed. We cannot calculate the hours on V2.04 or higher upgraded machines, because it’s unknown how many of the hours are at double rate or at the correct rate. Correctly dividing the hours becomes impossible.