User’s Manual
K&F ‘SW’ Series Subwoofer Systems
KLING & FREITAG GMBH ©1998 - 2015
Version 5.1, 29.05.2015
Page 19 of 19
7.
Short Circuit Fuses in the K&F Subwoofer Systems
7.1
Risks of using High Performance Power Amplifiers
In recent years, power amplifiers have achieved increasingly higher levels of perfor-
mance. Some of them can be operated with low-impedance loads. There are, therefore,
strong power amplifiers that can reliably work with impedances below 1
Ω
. This devel-
opment has led to an increased safety risk during defective operations.
When there is a defect, such as a short circuit in the speaker chassis or on the crossover,
it is possible that the power amplifier --- despite existing protective switches --- will not
shut off. Long cable lengths and contact resistance on the plug connections may already
have an electrical resistance of 1
Ω
. As a result, the power amplifier cannot ‘‘recognise’’
the operations as being defective and, therefore, delivers unacceptable high currents. In
the worst-case scenario, this may lead to fire damage (hot and charred wiring / con-
nectors as a result of overloaded conductors and connectors, etc.).
The current safety
regulations are lagging behind this development and are thus not up-to-date with this
modern technology.
In order to give consideration to this development, Kling & Freitag now equips its sub-
woofer systems with short circuit fuses at the signal input. These fuses do not offer
protection for the speaker, but do reduce the risk of consequential damage in the case
of a short circuit.
For systems, which are not serially equipped with a short circuit fuse, Kling & Freitag
offers simple add-on kits so that you can adapt your existing subwoofer systems to the
current power amplifier development.
7.2
Identifying the Models with Short Circuit Fuses
The subwoofer systems, which are serially equipped with, fire safety fuses can be identi-
fied as follows; both mentioned stipulations must be fulfilled:
POWER: 700W
WT: 51,5kg
XO-ON OFF
SER.-NO.:
2 5 0 8 0 0 0 0 0 7 0
IMP: 6
A dobe Sy stems
All subwoofer systems, which are not serially equipped with short circuit fuses, can be, if
required, easily and inexpensively upgraded even by yourself.
An instruction manual for this upgrade is delivered with the add-on kit.
7.3
Specification of the Fuses
The fuses in all models have the following identical specifications:
Bussmann S 506
Bussmann S 506
Bussmann S 506
Bussmann S 506----8A slow
8A slow
8A slow
8A slow
When necessary, these fuses may only be replaced with the aforementioned original
fuse.
The first two
digits must be at
least 25.
The next two
digits must be at
least 08.
