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3 Way Active Loudspeaker eng

2017-12-23 05:29  
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3-Way Active Loudspeaker

3_way_active_lsp_crossover.gif (13294 bytes)

After the2-way active loudspeakercircuit, 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 ofFig.5. Exist the possibility is used other circuit crossover, as the circuit of3-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.

Part List[Fig.1]

R1=47KohmsR19-20=47ohmsC17-18=47uF 25V
R2=1KohmsC1=2.2uF 63V MKTTR1-2=47Kohms trimmer
R4-11-13-15-17=NCC3-4-11-12=100nF 63V MKTIC2-3=TL072-NE5532
R5-6=12KohmsC5-6-9-10=10nF 63V MKTJ1=2pin conn. 2.54mm pin step
R7-8=120KohmsC13=6.8nF 63V MKTJ2A=8pin conn. 2.54mm pin step
R9-10=220KohmsC14=3.3nF 63V MKTor 8 pinhead 2.54mm pin step*
R12-14=10KohmsC15=33nF 63V MKT
R6-18=33KohmsC16=18nF 63V MKTAll Resistors is 1/4W 1%

Typical specifications

Input sensitivity


Input impedance


High Pass filter


Band Pass filter


Low Pass filter




3_way_active_lsp_protection.gif (21482 bytes)

The protection circuit from DC voltages [Fig.2] and  delay connection the speakers is the same with what exist in2-way active loudspeakerwhere 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.

Part List[Fig.2]

R1=470ohms 1WC4=10uF 25VIC1=4093
R2-3=1MohmsC5=1uF 25VIC2=7812
R4=22KohmsC6=4.7uF 25VIC3=7815
R5-21=33KohmsC7-8-10-11-13-14=33uF 63VIC4=7915
R6-8-16=15KohmsC9-12-15=22uF 16VQ1-2=BD678
R7-9-17=56KohmsC16-17=2200uF 25VQ3-4-5=BC550C
R10-23-18=56KohmsC22-23=10uF 25VRL1-2=12V RELAY G2R2 [OMRON]
R11-12-19=10KohmsD1-2-3-4=1N4002J2B=8pin conn. 2.54mm pin step
R14-15-20=3.9KohmsD5=8.2V 1W ZenerJ3B=3pin conn. 2.54mm pin step
R22=1KohmsD6-7.....26=1N4148J8A-B=2pin conn. 2.54mm pin step male-female
C1=100uF 25VD27=Led 5mm
C2-3-18-19-20-21=100nF 63V MKTBR2=BRIDGE RECT. 80V 1.5AAll Resistors is 1/4W 1-5%

3_way_active_lsp_power.gif (30880 bytes)

In theFig.3, exist the circuit of power amplifiers that drive the corresponding speakers. The choice are also here theSTK4044XIof 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 clueXIbecame because it has better and more modern internal designing, as regards types II and V. It can used also other types [BandV] 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.

Part List[Fig.2]

R23-33-43-32-42-52=1KohmsRLF1...3=FILTER* See textC32-46-50=1nF 63V MKT
R24-34-44=47KohmsC24-38-52=330pFC33-37-47-51-63-65=100uF 63V
R25-26-35-36-45-46=100ohmsC25-39-26-40-54=1uF 63V MKTC34-48-62=220uF 25V
R27-37-47=1KohmsC53=2.2uF 63V MKTC35-36-49-50-61-64=10uF 63V
R28-38-48=0.22ohms 5WC27-28-42-56-41-55=100pFC66-67-68-69=15000uF 63V
R29-39-49=4.7 ohms1WC29-43-57=100pFIC5-6-7=STK4044XI* See text
R30-40-50=56KohmsC30-44-48=15pFF2-3=Fuse 5A Fast 5X20mm PCB case
R31-41-51=10KohmsC31-45-59=100nF 100V MKTJ4A-5A-6A=2pin conn. 3.96mm pin step

Typical specifications

Input sensitivity


Input impedance


Output Power  (0.1% THD)

100W/8 ohm per Band

Power Supply


Block Diagram

3_way_active_lsp_block.gif (16806 bytes)

In theFig.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 outputsA=2X38Volts andB=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.

Part List[Fig.2]

T1=110-230Vac||A=2X38V  >350VAJF2=Female RCA JackMID=MIDRANGE 8 ohms
                        B=2X15V     30VAF1=FUSE 1.2A SLOW CASEWOO=WOOFER 8ohms
JF1=3pin male supply jackTW=TWEETER 8R

Filter_butterworth_12dB.gif (5974 bytes)

Fig.5--Crossover calculation

3-Way Active Loudspeaker - Main PCB  [88kb]
3-Way electronic crossover -12dB/oct - PCB  [24kb]
3-Way Active Loudspeakerin Greek


Sam Electronic Circuits9/02

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