Car Subwoofer Driver Diagram
Saturday, October 17, 2009
Car Subwoofer Driver Diagram- Circuit description:
The stereo signals coming from the line outputs of the car radio amplifier are mixed at the input and, after the Level Control, the signal enters the buffer IC1A 
and can be phase reversed by means of SW1. This control can be useful to allow the subwoofer to be in phase with the loudspeakers of the existing car radio.
Then, a 12dB/octave variable frequency Low Pass filter built around IC1B, Q1 and related components follows, allowing to adjust precisely the low pass frequency from 70 to 150Hz.
Q2, R17 and C9 form a simple dc voltage stabilizer for the input and filter circuitry, useful to avoid positive rail interaction from the power amplifier to low level sections.
Notes:
- IC2 must be mounted on a suitable finned heatsink
- Due to the long time constant set by R17 and C9 in the dc voltage stabilizer, the whole amplifier will become fully operative about 15 - 30 sec. after switch-on.
Technical data:
- Output power (1KHz sinewave):
- 22W RMS into 4 Ohms at 14.4V supply
- Sensitivity:
- 250mV input for full output
- Frequency response:
- 20Hz to 70Hz -3dB with the cursor of P2 fully rotated towards R12
- 20Hz to 150Hz -3dB with the cursor of P2 fully rotated towards R11
- Total harmonic distortion:
- 17W RMS: 0.5% 22W RMS: 10%
