Acoustics; Figure 46. A-Weighted Sound Power Levels - IBM IC35L036UWDY10 - Ultrastar 36.7 GB Hard Drive Specifications

7.9 Acoustics

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.
Model Mode
Idle
146 GB
Operating
Idle
all other models
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 com-
mands except approximately once per minute when the idle time function sweeps the disk surface.
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 calculated per the formula 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)
Typical
3.7
4.5
3.4
4.5
Ultrastar 146Z10 hard disk drive specifications
43
Maximum
4.1
4.8
3.8
4.8