Monday, September 14, 2020


12V Subwoofer amplifier

Hello friends, in this post I will make an amplifier kit, using the TDA8954TH class-d amplifier chip that I have previously made, but in this post, I will make a complete amplifier with a subwoofer preamp and also a DC to DC converter circuit, where is the power This amplifier can be supplied using a 12VDC voltage or using a battery, or a 12V battery. The purpose of which is applied to car audio such as monoblock car amplifiers, but this amplifier is also multifunctional, can be used for home audio, the output can be flat, or stereo.

The following is the circuit of the TDA8954 power amplifier along with the converter and subwoofer preamp. 

Downloadable schematic .PDF 

The DC to DC converter circuit, the PWM IC uses TL494, the mosfet uses 6 N-channel Mosfets. For the transformer can use ferrite EE or Toroid. with the number of turns as shown. The primary wire size must be larger than the secondary by a 3: 1 ratio.

12VDC CT for opamp circuit or subwoofer preamp. and this 5V to supply to pin MODE TDA8954.

Then I took the protection from the diagnostic output of TDA8954. so when the amplifier has a problem, the diagnostic pin will send a command to the protection section to turn off the PWM converter for 100mS and will activate again when the amplifier is normal, and this is not in lock mode, except for OVER TEMPERATURE. in case of overheating, the converter will shut off completely until the kit is switched on again and is cool. Over-temperature around 120 degrees Celsius.

I added a series of subwoofer filter circuits, it could also be flat, by changing this jumper pin. or it can also be used for stereo, but only for flat if there is a stereo, no a subwoofer. Subwoofer filter especially for BTL. There is also a subwoofer frequency setting, subsonic filter, bass boost, and gain.

The TDA8954TH circuit is still the same as before, but what is different is the LPF part, I use a single core, diameter 3.3cm. The performance of this amplifier is around 420W according to the datasheet, for a load of 8 Ohms in BTL mode, and 4 ohms in stereo mode. For BTL it is not recommended for speakers below 8 Ohm because later it will be easy to Over Current, it can cause the sound to be broken because when the overcurrent amplifier is restarted, it will dive for 100mS and it is sustainable. So adjust the load to a maximum of 8 ohms for BTL.

And I have designed the following PCB, with a double layer path, as usual, this PCB can be downloaded at the link at the end of the Gerber format post, along with the component list files, schematics, and CPL files.


Step-up transformer, I use a ferrite core ee42, with the number of primary turns 5 + 5 turns. secondary 13 + 13 convolution. the secondary voltage is around 32VDC CT. This is for the 5VDC aux, the number of turns 3, and this for the 12VDC CT aux opamp the number of turns 6 + 6 turns.

For the LPF inductor, the amplifier can use an MS13060 core or you can also use a 77071A7 series core with the same outer diameter of about 3.3cm. because this amplifier is BTL or STEREO so it requires two inductors, but I only use a single core with 2 inductor turns, the way it is twisted is made in the same direction, the number of turns using 1mm wire produces an inductance value of around 22uH x 2.

Download Schematic, BoM, PCB Layout Gerber, CPL Files:


Extract file before using

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