14W HI-FI AUDIO AMPLIFIER

TDA2030(B)

第 8 页 共 14 页

MULTIWAY SPEAKER SYSTEMS AND ACTIVE BOXES

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 covered 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. 2).As an example, a 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 air cored 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 is shown

in Fig.3.

The proposed circuit can realize combined power amplifiers and 12dB/octave or 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 100Ω,while that of the Pin (+) is very high, which is also what

was wanted