3-Way Active Loudspeaker

After the 2-way active loudspeaker circuit, give a complete electronic section circuit of one 3-way active loudspeaker. The speaker�s choice will become from you, because the particular circuit has the driving possibility all almost trade loudspeakers. The choice that made in the crossover stage, is a 3-way crossover [Butterworth] with cut off -point frequencies 200HZ and 3500HZ, with slope -12dB/oct. These frequencies can change and adapted in your own speaker�s choice, using the calculation types of Fig.5. Exist the possibility is used other circuit crossover, as the circuit of 3-way active crossover with slope -24dB/oct. The circuit crossover does not exist above in main PCB, but is contact with this via the plug J2A that is applied above in the J2B. This can become if in the place of J2A it�s placed a pinhead with 8 pin and PCB crossover put on above main PCB in form sandwich. It can however be placed in other point and with a flat cable to transport the signals and the voltages from J2A in the J2B. Power supply for � 15V of the crossover circuits it�s found in main PCB. A point that I want to highlight is with regard to various in the calculation values precision and real values of resistors and capacitors. It�s good, if the component value does not exist in standard value to select a combination that us will give value near in theoretical and simultaneously to do the same and in the other loudspeaker, in order that the divergence is same. In the drawing exist parallel combinations resistors, and somebody�s from these are not used if they do not need. With the TR1-2 we adjust the level of high and mid speakers, if it needs.

The protection circuit from DC voltages [Fig.2] and  delay connection the speakers is the same with what exist in 2-way active loudspeaker where exists and the relative description. They exist certain various, as has been added a detection stage of continuous voltages and a relay [RL2]. The contacts of RL1 connect the speakers the high and mid frequencies, the two contacts of RL2 are connected at the parallel and connect the speaker of low frequencies in the exit of IC7. Here exist also the stage of � 15V supply for the crossover and suffices for each choice of crossover circuit.

In the Fig.3, exist the circuit of power amplifiers that drive the corresponding speakers. The choice are also here the STK4044XI of SANYO with output power roughly 100W each one, power that consider that is very good for the drive the majority of speakers of trade, in high levels. The sound quality that produces is very good. The type choice with clue XI became because it has better and more modern internal designing, as regards types II and V. It can used also other types [ B and V] without exists some problem. Filters RLF1�3 are made by a resistor 10R 3W that to around her we wrap roughly 30 coils in three layer, wire from cupreous insulated with diameter 1mm. The capacitors C66�. 69 are placed above in main PCB and near in the power amplifiers.

In the Fig.4, appear a big part of various stages and connections between them. As it appears the speakers are placed in suitable wooden box. In his rear part of box and on a leaf of aluminum are placed the power transformer T1, the power bridge rectifier BR1, the switch S1, the main power plug JF1, fuse F1, the RCA plug JF2 and the indicative led D27. Transformer T1 has two outputs A=2X38Volts and B=2X15Volts. Bridge BR1 clinching above in aluminum so that it�s frozen. On a big heatsink clinching the IC5-6-7. In plug JF2 enter the acoustic low level signal from the preamplifier exit. Good it�s the crossover PCB it�s found far by the T1 transformer.

Fig.5--Crossover calculation

• 3-Way Active Loudspeaker - Main PCB   [88kb]

• 3-Way electronic crossover -12dB/oct - PCB   [24kb]

• 3-Way Active Loudspeaker in Greek