Power amplifier design and protections
Quite some of the power amplifier topology of the X-Amps derives from the meanwhile legendary LINEAR
PRECISION Series amplifiers. The X 1202 power amps offer a class A/B design, while the X 1201 Single
Channel power amplifier is based on the “Grounded Bridge” technology. These power amplifier designs
have stated their capabilities several thousand times and therefore guarantee truly superb quality audio
performance and a maximum in operational stability. Optimizing the power amplifiers’ weight and thermal
behavior was possible without compromising their outstanding output power capacity, dynamic response,
and transmission quality.
Compared to conventional designs, the X-Amp Series power amplifiers provide several details in
electronic circuitry, and protections design that normally are not perceptible for the user, and yet they are
responsible for the absolute stable operation of X-Amps. Here is a list of some of these functions:
Back-EMF Protection, to protect the output stage transistors against electrical energy that is returned
from reactive loads and being re-induced into the amplifier outputs.
Peak Current Limiter, protects the power amplifier against peak output currents that result from the
connection of extremely low loads (below 2 ohms) and high modulation at the same time.
DC/HF Protection, protects the connected loudspeaker systems and the power amplifier against the
occurrence of DC or HF at the output of the power amplifier.
Thermal Protection, is activated if the output stage power transistors or the mains transformer suffer
from thermal overload; e. g. at extreme high environmental temperatures in a rack-shelf system
(insufficient ventilation) and extreme long lasting continuous operation with 2 ohms loads connected.
Inrush Current Limiter, limits the mains current during the power-on operation of the power amplifier
and therefore prevents the installation’s mains fuse from being blown.
Turn-on delay, protects the connected loudspeaker systems against power-on impulses.
The power amplifier immediately enters Protect Mode if one of these protections is activated. The output
relays separate the connected load from the power amplifier output to prevent the loudspeaker systems
and/or the power amplifier itself from being damaged.
There are other limiting functions and control mechanisms that are activated when needed; these are:
Dynamic Limiter, is controlled by extremely fast operating audio processors, which constantly monitor
the input and output voltages of the power amplification blocks and is activated whenever audible
non-linearity occurs; e. g. power amplifier clipping. This guarantees distortion-free reproduction and
reliable protection of the connected loudspeaker systems even at extremely high output levels.
Thermal Brain Circuit, is activated in association with the use of several different Xm-modules. During
dynamic peaks, the actual output power capacity of the X-Amp Series power amplifiers can easily exceed
the stated rated value, resulting in exceptionally dynamic reproduction of the entire sound system. If the
loudspeaker systems suffer from thermal overload over a longer period of time, they definitely get
damaged. The thermal brain circuits simulate the loudspeaker systems’ thermal behavior. Whenever the
thermal limit is exceeded, they temporarily reduce the energy that is fed to the loudspeaker systems.
X-Amp SYSTEM
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