Active Loudspeaker Amplifier with SKT4042

Posted on Oct 18, 2012

Active loudspeakers have a lot of advantages concerning simple loudspeakers that use passive components for the elements concretisation of segregation of frequencies. In the case of active loudspeakers we have, proportionally, bigger build cost, because each loudspeaker is led by his own power amplifier. In properly drawn active loudspeaker, the quality of sound is much better and the distortions very low, because it does not use inductors and large capacitors in the road of signal. All capacitors exist in the signal road, they have very small value and they are very good quality. This does not mean that one well drawn passive loudspeaker is not good, perhaps better than one active. On the contrary one active loudspeaker is enough difficult in the manufacture.

Active Loudspeaker Amplifier with SKT4042
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Active Loudspeaker Amplifier with SKT4042 - image 1
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In the [Fig.1], exist a circuit of 2-way active loudspeaker. As we see also in the Block diagram [Fig.2], exist one classic 2-way crossover with cross frequency fc=3100HZ [-24dB/oct]. This frequency was selected, because it is near in the cross frequency of many speakers of trade, it can however change and be adapted in your own speakers choice, it?s enough you use the types that give for calculation [Fig.3]. The IC1 makes the input adaptation, the filters round the IC2 creates a high-pass filter of frequencies, for frequencies above Fc=3100HZ, on the contrary the components round the IC3 creates a low-pass filter, for frequencies under 3100HZ. With the trimmer TR1 in the line of high frequencies we can adaptable, if it needs, the level between the two speakers. Usually it will need we lower at 10% the level tweeter concerning woofer. In a lot of points of filter exist capacitors and resistors that are not used, but are there for future changes, in a other cross frequency, as the R6 and R10 that are not used. To the next stage the two outputs of filter are drive to the two power amplifiers, the IC4 for the high frequencies and the IC5 for low. Those of are two hybrid IC by Sanyo, with output power 80W/8ohms, with very good characteristics and sound. It can become change with other type of series as STK4036, STK4038, STK4040, with proportional modification of power supply voltage. The particular line is used in enough...

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