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11. USING THE AMPLIFIER WITH AN ACTIVE CROSSOVER
This section describes how to connect and set up the Emperor Integrated amplifier in a fully active system.
This is where the audio signal is split into the bands required by each section of the loudspeaker at low
level using an active crossover. Each band is then fed to a separate power amplifier to drive its section of
the loudspeaker. The loudspeaker has no internal passive crossover and its drivers are connected directly
to its input terminals.
In this example we are illustrating how a system with a 3-way loudspeaker would be configured – figure 6.
With a 2-way loudspeaker only one additional power amplifier per channel would be needed.
We have shown the German Physiks Emperor DSP-X active crossover in our illustration, however any 3-
way active crossover could be used, though with not necessarily such good results! One of the many
advantages of the Emperor DSP-X is that if it is to be used with a set of German Physiks loudspeakers, it
will be shipped pre-configured for the model concerned. The user then simply has to connect it into the
system and switch it on.
We have also shown stereo power amplifiers in our illustration, in this case the German Physiks Emperor
Stereo Power amplifier. This will work particularly, well as its power section is exactly the same as that
used in the German Physiks Emperor Integrated amplifier, so the gains are the same and they are matched
tonally. You could use other makers’ stereo or mono power amplifiers, provided that they all had the same
gain as the Emperor Integrated amplifier.
For clarity, the connections for only one loudspeaker are shown in figure 6.
What are the advantages of an active system?
Although an active system is much more complex and therefore more expensive than a passive system, it
offers several advantages, which are especially useful in very high-end systems.
1. There is usually very little scope to adjust the frequency characteristics of a passive crossover to
compensate for variations in frequency response caused by individual room acoustics. The Emperor DSP-
X provides two means of adjustment to enable a more even frequency response to be achieved. The
relative levels of the 3 output sections may be adjusted via a front panel control and more sophisticated
adjustments may be made using a remote-control application.
2. In an active system, the elimination of the passive crossover allows the power amplifiers to be connected
directly to the drivers. This greatly improves the damping of the driver movement. This principally affects
the low frequency drivers, significantly improving the clarity of the bass.
3. Resistive components in a passive crossover dissipate power. Eliminating these improve both the
efficiency and the dynamic response of the system. More power can reach the drivers and the amplifiers
work with more headroom.
4. The use of a digital filter allows the loudspeaker designer to get much closer the exact filter characteristic
that they wanted, without having to accept the compromises imposed by the limitations of passive designs.
5. If a passive crossover is driven at high levels for a prolonged period, it can result in the resistive
components heating up sufficiently for their values to change and have an effect on the crossover’s
characteristics. Whilst this is usually a minor effect, the Emperor DSP-X eliminates the possibility of this
occurring.
In our experience, with a very high-end system where changes are more easily heard, the improvement in
sound quality, especially in the areas of bass clarity and overall transparency that the Emperor DSP-X
crossover provides, would be difficult to achieve by other means. This improvement is enhanced by the
Emperor DSP-X’s equalisation adjustment features.
