Acoustics; Sound Power Levels - IBM Ultrastar 36LZX Specifications

7.9 Acoustics

7.9.1 Sound power levels

The upper limit criteria of the A-weighted sound power levels are given in Bel relative to one pico watt
and
are shown in the following table. The measurement method is in accordance with ISO7779. Drives are
to meet this criteria in both board up and board down orientations.
Mode
Idle
Operating
Figure 46. A-weighted sound power levels
Background power levels of the acoustic test chamber for each octave band are to be recorded. Sound
power levels are measured with the drive supported by spacers so that the lower surface of the drive is
located 25 ± 3mm height from the chamber desk. No sound absorbing material shall be used. The
acoustical characteristics of the drive subsystem are measured under the following conditions.
Idle mode:
Powered on, disks spinning, track following, unit ready to receive and respond to control line
commands.
Operating mode:
Continuous random cylinder selection and seek operation of the actuator with a dwell time at
each cylinder. Seek rate for the drive is to be calculated as listed below;
Ns = 0.4 / (Tt + Tl)
Ns = average seek rate in seeks/sec.
Tt = published random seek time.
Tl = time for the drive to rotate by half a revolution.
A-weighted sound power level [Bel]
3.9 (Typical)
4.8 (Typical)
Ultrastar 36LZX hard disk drive specifications
4.3 (Max)
5.0 (Max)
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