150W Subwoofer

It may seem a little excessive, but since I had the programmer, the C compiler and some spare PIC16F627 chips, this solution to handling power on mute, 12V trigger powering and LED for status would be small, reliable and cheap.

Three relays would be involved.
Mains switching relay, to switch in the 225VA toriodal transformer
Output switching relay, to disconnect the speaker from the amp
Input switching relay, to remove any input so the output switching relay switches a very small current, prolonging its life (thanks to Mark Hennessy for this idea).

Two LEDs would be on the front of the box. One LED for standby, one (blue) LED for power on. The would both flash in turn when the power on sequence runs.

Finally, there would be two inputs. One small push button for mounting on the front of the case for manual power on/off, and one 12V trigger input, isolated using a standard opto-isolator in order to prevent earth loops.

Thats all there is to it. Without the PCB mount transformer, the PCB turns out pretty small. It has been desgined to fit my relays (and other components) I had available to me, but is provided as a scan below if you want to use (and modify it in your subwoofer/power amplifier project. The C file, and HEX file for the PIC micro is also provided.

Origial Article sourse e-dan.co.uk

50 Watt Subwoofer Amplifier

R1  200 Ohm 1/4 W Resistor
R2  200K 1/4 W Resistor
R3  30K 1/4 W Resistor
R5  1K 1/4 W Resistor
R6  5K 1/4 W Resistor
R7,R10  Meg (5%) 1/2 W Resistor
R8,R9  0.4 Ohm 5 W Resistor
R11  10K Pot
R12,R13  51K 1/4 W Resistor
R14  47K 1/4 W Resistor
C1  100uF 35V Electrolytic Capacitor
C2  0.011uF Capacitor
C3  3750pF Capacitor
C4,C6  1000pF Capacitor
C5,C7,C8  0.001uF Capacitor
C9  50pF Capacitor
C10  0.3uF Capacitor
C11,C12  10,000uF 50V Electrolytic Capacitor
U1,U2  741 Op Amp
U3  ICL8063 Audio Amp Transister Driver thingy
Q1  2N3055 NPN Power Transistor
Q2  2N3791 PNP Power Transistor
BR1  250 V 6 Amp Bridge Rectifier
T1  50V Center Tapped 5 Amp Transformer
S1  SPST 3 Amp Switch
S2  DPDT Switch
F1  2 Amp Fuse
SPKR1  8 Ohm 50W Speaker
MISC  Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2

60W Subwoofer Amplifier Circuit

The output power: 40 w 8 ohm and 60 w 4 ohm load. Preamplifier is used in the same 60 v rails as the power amplifier gain blocks can implement two transistors can provide about 20 v RMS output. This provides a very high input overload. List at least the recommended value is C8. 3300μf capacitor or two 2200μf capacitors connected in parallel would be a better choice. Darlington transistor types of alternative has MJ11014 (Q3) and MJ11013 (Q4) or TIP142 (Q3) and TIP147 (Q4). T1 transformer can be also a 24 24 v or 25 25 v type (ie. 48 v or 50 v center tapped). SW1 switch insert low-cut feature when open. In all cases, Darlington transistors are used as the output device is essential that the transistor (Q2) pass in close thermal contact with the sensor output transistors as possible.

R1__________________6K8    1W Resistor
R2,R4_____________470R   1/4W Resistors
R3__________________2K   1/2W Trimmer Cermet
R5,R6_______________4K7  1/2W Resistors
R7________________220R   1/2W Resistor
R8__________________2K2  1/2W Resistor
R9_________________50K   1/2W Trimmer Cermet
R10________________68K   1/4W Resistor
R11,R12______________R47   4W Wirewound Resistors

C1,C2,C4,C5________47μF   63V Electrolytic Capacitors
C3________________100μF   25V Electrolytic Capacitor
C6_________________33pF   63V Ceramic Capacitor
C7_______________1000μF   50V Electrolytic Capacitor
C8_______________2200μF   63V Electrolytic Capacitor (See Notes)

D1_________________LED    Any type and color
D2________Diode bridge   200V 6A

Q1,Q2____________BD139    80V 1.5A NPN Transistors
Q3_____________MJ11016   120V 30A NPN Darlington Transistor (See Notes)
Q4_____________MJ11015   120V 30A PNP Darlington Transistor (See Notes)

SW1_______________SPST Mains switch

F1__________________4A Fuse with socket

T1________________220V Primary, 48-50V Secondary 75 to 150VA Mains transformer

PL1_______________Male Mains plug

SPKR______________One or more speakers wired in series or in parallel
                  Total resulting impedance: 8 or 4 Ohm
                  Minimum power handling: 75W

Subwoofer Amplifier 100W

R1 - 6K
R2 - 6K
R3 - 130K
R4 - 22K
R5 - 15K
R6 - 3.2K
R7 - 300 Ohms
R8 - 30 Ohms
R9, - R10 3 K
C1, - C2 0.1uF, electrolyte
C3,- C5,C6 10uF, electrolyte
C4 - 1uF, electrolyte
Q1 - 2N222A
Q2 - TIP41
Q3 - TIP41
Q4 - TIP147, PNP
D1, - D2 1N4007
Dual Supply -  +/-30V

Car Subwoofer

Transistor subwoofer circuit diagram 300W

more info sound.westhost.com/project68.htm

Subwoofer Amplifier 100W

General Description

The TDA7293 is a monolithic integrated circuit in Multiwatt15 package, intended for use as audio class AB amplifier in Hi-Fi field applications, such as home stereo, self powered loudspeakers and Topclass TV. Thanks to the wide voltage range and to the high output current capability it is able to supply the highest power into both 4-Ω and 8-Ω loads.The built-in muting function with turn-on delay simplifies the remote operation avoiding on-off switching noises. Parallel mode is possible by connecting several devices and using pin11. High output power can be delivered to very low impedance loads, so   optimizing the thermal dissipation of the system.

Features:

• Multipower BCD technology
• Very high operating voltage range (±50 V)
• DMOS power stage
• High output power (100 W into 8 Ω 
• THD =10%, with VS = ±40 V)
• Muting and stand-by functions
• No switch on/off noise
• Very low distortion
• Very low noise
• Short-circuit protected (with no input signal applied)
• Thermal shutdown
• Clip detector
• Modularity (several devices can easily be connected in parallel to drive very low impedances)

Circuit diagram