iPAM400 – Product Manual
U-0629-0171.doc – Issue: 04 complete, approved
Page 21 of 138
2.4.3.2 DC Blocking Capacitor Values
All loudspeakers connected to the system must be fitted with DC blocking capacitors. Loudspeakers are
available with suitable capacitors pre-installed from a variety of suppliers. Alternatively, DC blocking
capacitors may be retrofitted.
Kits of DC blocking capacitors are available from ASL; see Table 1.
For further details of the DC blocking capacitors, please refer to EOL10K user documentation; see Table 7
(page 132).
Table 1 DC blocking capacitor kits and capacitance values
Maximum Loudspeaker Power Rating
(Power Tapping - W)
ASL Part Number
(10 pack)
Capacitance Value (µF)
2 LBC2W 0.33
6 LBC6W 1
14 LBC14W 2.2
30 LBC30W 4.7
63 LBC63W 10
1) The capacitance values listed above will provide negligible attenuation of –3 dB at 100 Hz.
2) If alternative capacitors are to be fitted, they must be non-polarized and rated to at least 250 V DC
and 160 V AC. Polyester sealed case types are recommended.
3) If improved low-frequency performance is required, the DC blocking capacitors may be increased
in value. Doubling the value will halve the ‘–3dB’ frequency.
4) Other values may be calculated from the following formula:
C =(16 x P) ÷ F
C = Minimum capacitor value in µF (round up to preferred value)
P = Power tapping of loudspeaker in watts
F = Required bottom end (–3dB) frequency response in Hz
2.4.4 Loudspeaker Line Monitoring using AC Surveillance
AC line surveillance is BS EN5839 Part 8 compliant and is carried out using one ASL AEL01 or AEL02 Active
End of Line Device fitted at the end on the loudspeaker circuit across the 100 V line.
The AEL01 and AEL02 enable line monitoring of either single (A) or dual A&B loudspeaker circuits without
the need for DC blocking capacitors in the loudspeakers. In dual A&B loudspeaker circuits application the
surveillance system identifies and isolates the faulty circuit in the event of short circuit.
The AEL01 and AEL02 use the same circuit board providing the same functionality in different enclosures:
• AEL01: IP55 rated UL94VO PVC enclosure
• AEL02: IP65 rated die-cast aluminium enclosure
Please refer to the AEL01 or AEL02 customer documentation for further details; see Table 7 (page 132)
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