CHAPTER 2: THE MPS-488P POWER SUPPLY
12
Each MPS-488P comes with Phoenix 5-pin female cable
connectors for assembling HMS-10 loudspeaker cables. For
information on HMS-10 cable requirements, see “HMS-10
Current Draw and Cable Requirements” on page 15. For
information on cables and cable accessories available from
Meyer Sound, see Appendix A, “HMS-10 Accessories.” For
information on cable assembly, see Appendix B, “HMS-10
Cable Assembly.”
CAUTION: When wiring cable connections for
the MPS-488
P channel outputs, it is extremely
important that each pin in the connector is wired cor-
rectly. Make sure the 48 V DC from the MPS-488
P is
wired directly (and only) to the 48 V DC pins on the
HMS-10 connector, and that the polarity is observed
(negative to negative, positive to positive) to avoid
damage to the loudspeaker. In addition, make sure
the audio pins are wired correctly; polarity reversals
for audio signals will affect system performance.
NOTE: The MPS-488 power supply is available
in two models: the MPS-488
P, which is
equipped with Phoenix 5-pin male output connectors
(recommended for use with the HMS-10), and the
MPS-488
E, which is equipped with EN3 5-pin female
output connectors.
MPS-488P CURRENT DRAW
The current draw for the MPS-488P and its connected loud-
speakers is dynamic and fluctuates as operating levels
change. Since different cables and circuit breakers heat up
at varying rates, it is important to understand the following
types of current ratings and how they affect circuit breaker
and cable specifications.
■ Idle Current — The maximum rms current during idle
periods.
■ Maximum Long-Term Continuous Current — The
maximum rms current during a period of at least 10 sec-
onds. The Maximum Long-Term Continuous Current is
used to calculate temperature increases for cables, to
ensure that cable sizes and gauges conform to electrical
code standards. This current rating is also used as a rat-
ing for slow-reacting thermal breakers.
■ Burst Current — The maximum rms current during a
period of around one second. The Burst Current is used
as a rating for magnetic breakers. It is also used for cal-
culating the peak voltage drop in long AC cable runs
according to the following formula:
V pk (drop) = I pk x R (cable total)
■ Ultimate Short-Term Peak Current — A rating for fast-
reacting magnetic breakers.
■ Inrush Current — The spike of initial current encoun-
tered when powering on.
You can use the following table as a guide for selecting
cable gauges and circuit breaker ratings for the system’s
operating voltage.
The minimum electrical service amperage required by an
MPS-488
P is the sum of the Maximum Long-Term Continu-
ous Current for all HMS-10s connected to the MPS-488
P.
An additional 30 percent above the minimum amperage is
recommended to prevent peak voltage drops at the service
entry.
NOTE: For best performance, the AC cable
voltage drop should not exceed 10 V, or
10 percent at 115 V and 5 percent at 230 V. Make
sure that even with AC voltage drops that the AC
voltage always remains within the operating window.
SAFETY ISSUES
Pay close attention to these important electrical and safety
issues.
■ The MPS-488P requires a grounded outlet.
Current Draw for MPS-488P with Four HMS-10s
Current Draw
(Four HMS-10s)
115
V AC
230
V AC
100
V AC
Idle Current 1.16 A rms 1.00 A rms 1.26 A rms
Maximum Long-Term
Continuous Current
3.92 A rms 2.11 A rms 4.48 A rms
Burst Current 9.84 A rms 5.40 A rms 10.76 A rms
Ultimate Short-Term
Peak Current
11.20 A peak 6.60 A peak 12.20 A peak
Inrush Current 15.20 A peak 9.36 A peak 17.60 A peak
Earth ground
Chassis ground
