TDA2030A
LINEAR INTEGRATED CIRCUIT
Multiway loudspeaker systems provide the best possible acoustic performance since each loudspeaker is
specially designed and optimized to handle a limited range of frequencies. Commonly, these loudspeaker systems
divide the audio spectrum two or three bands.
To maintain a flat frequency response over the Hi-Fi audio range the bands cobered by each loudspeaker must
overlap slightly. Imbalance between the loudspeakers produces unacceptable results therefore it is important to
ensure that each unit generates the correct amount of acoustic energy for its segments of the audio spectrum. In this
respect it is also important to know the energy distribution of the music spectrum to determine the cutoff frequencies
of the crossover filters(see Fig. 18).As an example,1 100W three-way system with crossover frequencies of 400Hz
and 3khz would require 50W for the woofer,35W for the midrange unit and 15W for the tweeter.
Both active and passive filters can be used for crossovers but active filters cost significantly less than a good
passive filter using aircored inductors and non-electrolytic capacitors. In addition active filters do not suffer from the
typical defects of passive filters:
--Power less;
--Increased impedance seen by the loudspeaker(lower damping)
--Difficulty of precise design due to variable loudspeaker impedance.
Obviously, active crossovers can only be used if a power amplifier is
provide for each drive unit. This makes it
particularly interesting and economically sound to use monolithic power amplifiers.
In some applications complex filters are not relay necessary and simple RC low-pass and high-pass
networks(6dB/octave) can be recommended.
The result obtained are excellent because this is the best type of audio filter and the only one free from phase and
transient distortion.
The rather poor out of band attenuation of single RC filters means that the loudspeaker must operate linearly well
beyond the crossover frequency to avoid distortion.
A more effective solution, named "Active power Filter" by SGS is shown in Fig. 19.
The proposed circuit can realize combined power amplifiers and 12dB/octave or 18dB octave high-pass or low-
pass filters.
In proactive, at the input pins amplifier two
equal and in-phase voltages are available, as required for the active
filter operations.
The impedance at the Pin(-) is of the order of 100
W,while
that of the Pin (+) is very high, which is also what was
wanted.
Fig. 18 Power distribution vs.
frequency
100
IEC/DIN NOISE
SPECTRUM
FOR SPEAKER
TESTING
MULTIWAY SPEAKER SYSTEMS AND ACTIVE BOXES
Fig. 19 Active power filter
80
C1 C2 C3
Morden
Music
Spectrum
Vs+
RL
60
R1 R2
R3
Vs-
3.3kW
40
20
100W
0
1
10
2
10
3
10
4
10
5
10
Contek Microelectronics Co.,Ltd.
CONTEK
http://www.contek-ic.com E-mail:sales@contek-ic.com
9
ETC [ ETC ]
