TDA2003 Amplifier

[Nigel Goodwin]

Have you tried it?, MOST audio amplifiers connect the speaker to ground, and they all motorboat with supply decoupling and impedance problems. I've seen far more grounded speaker systems motorboat that +ve speaker systems, although that's only because of the much larger number of grounded speakers!.

 

[audioguru]

Many cheap audio amps with the speaker grounded motorboat because they become relaxation oscillators:
1) They draw current from the supply to charge the output cap into the speaker.
2) The supply voltage drops so much that the amp doesn't work anymore, stopping the current and the supply voltage begins to rise.
3) When the supply voltage rises high enough then the amp begins the cycle over again. :lol:

 

[m_sh84]

can any one explain this for me plzzz

heloooo evryone
can anyone tell me how did he choose these valuse for the capcitors and resistors ? and why these values how can i controlr the amplifiction ?

thanks in advance

 

[audioguru]

Re: can any one explain this for me plzzz

heloooo evryone
can anyone tell me how did he choose these valuse for the capacitors and resistors ? and why these values how can i controlr the amplifiction ?

Usually there are complete circuit designs and even a pcb layout in the datasheet for an audio amplifier IC.
Coupling capacitors cutoff low frequencies so first select a wanted frequency then determine the source and load impedances for the capacitor. Then a simple standard formula is used to pick the capacitor's value.
Resistor values are copied from the circuit shown on the datasheet or can be calculated with a simple standard formula.
A volume control is usually used at the input of an audio amplifier to adjust its gain. A simple standard formula is used to change the max gain.

 

[gimmychen]

BTW,how to minimize the power up "pop"

Is this done this way to minimize the pop when the power is switched on?

I use 2 tda2003 for Car audio,for minimize the "pop", we add a mos(2n7002)to pulldown the input of TDA2003,but still about 200mV Vp-p "POP" on the output,any one can help us?many thanks!

 

[mneary]

You need something that is already turned ON before the TDA2003 receives power. The 2N7002 needs 3V or more on the gate to conduct. Consider a junction FET.