Hi,
Speaker connect to TDA2003 Amplifier shall be connect to output (pin 4) and refer to ground.
What happend for abnormal design, where the speaker is refer to +12V?


I have test it, it work well.
But I would like to know if I will get into problem after a long run for this abnormal circuit?
( I connect to +12V is for compatible on existing speaker setup which prefer not to change.)

Thank you,

 

i don't think it will cause problems ..
since it is dc decoupled/ ac coupled . only difference shld be that when viewed thru oscilloscope , the waveforms are 180 degree out of phase.

 

It makes NO difference if you connect the speaker to positive or negative (signal wise they are both identical) - BUT you MUST reverse the direction of the speaker coupling capacitor C14, as it's then connected the wrong way round!.

BTW, there's nothing 'abnormal' connecting a speaker this way, it's fairly common practice!.

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is there any preferance/ advantage when connecting like this?..or is it done when the layout matters ?

 

The usual advantage (although it doesn't apply in the case of this IC) is that it can save you a boot-strap capacitor, the speaker coupling capacitor can be used to boot-strap the top output transistor, saving a seperate capacitor. You used to see it done a lot in low priced record players and radios.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

The TDA2003 is designed for high output current. An 8 ohm speaker doesn't need much current.
With the 12V supply, an 8 ohm speaker gets only 2W at an awful-sounding 10% distorted overdrive. At clipping it will be only about 1.5W.
Into a 1.6 ohm load (five paralleled 8 ohm speakers), the total power with 10% distortion is 8W.

Attached Images

tda2003.png (21.4 KB, 838 views)

__________________
Uncle $crooge

 

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

__________________
Ron

 

No, just to save a boot-strap capacitor (on amps that use them), there's no advantage on the TDA2003 circuit.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Thank you, will reverse polarity of C14.
How about C15 & R12, just leave it as it or refer to +12V?

 

You can minimize the turn-on pop of a single supply amp like this one if you allow the input capacitor to charge slower than the feedback capacitor but only if the load is cap-coupled to ground.
I think this amp would have a terrible BANG when it is turned-on.

__________________
Uncle $crooge

 

Is that pop caused due to initial charging of the i/p cap?, or does other capacitor in the ckt take its part ?

 

Since the input cap is discharged before the amp is turned on, when you turn it on then the input cap keeps the input voltage low until it charges, therefore the amp's output voltage is also low charging the big output cap suddenly through the speaker.
The pop will be much less if the speaker was connected to ground.

__________________
Uncle $crooge

 

It doesn't really matter!.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

I believe that we are assuming here that +12V is well-regulated and ripple-free. Any noise on +12V will show up across the speaker.

__________________
Ron

 

Certainly!
And if the supply has some internal resistance then the amp will make motorboating sounds like crazy due to positive feedback.

__________________
Uncle $crooge