Help with TDA2003 amp

Tahmid · 13th July 2008, 02:01 PM

Hi,
I just made a TDA2003 amp for my PC. I set the gain resistors at 4.7 ohm and 220 ohm. When I plug in the audio source, there is too much distortion that the actual music can barely be heard. I am running it from a 12v 4a power source i built myself.
What could be the reason for the distortion? What can I do to remove it?

I thank you in advance for any help i can get.

poynton · 13th July 2008, 02:14 PM

post the circuit and values you are using.

Andy

Tahmid · 13th July 2008, 02:34 PM

Here it is.
Please help me in this regard.

poynton · 13th July 2008, 02:57 PM

why did you not use the circuit in the application notes?

http://pdf1.alldatasheet.com/datashe...S/TDA2003.html

Andy

lineup · 13th July 2008, 04:45 PM

Quote:

Originally posted by Tahmid
Here it is.
Please help me in this regard.

Remove the C3 0.22u capacitor form output to GND.
Replace C8 0.22u, now across speaker output,
with one Capacitor 100nF + 1 Ohm in series, across speaker output.
Like C5 + R3 in my attached example from TDA2003 datasheet.

Datasheet TDA2003:
http://www.st.com/stonline/products/...re/ds/1449.pdf

destroyer X · 14th July 2008, 12:46 AM

resistances.... and you have 220 and 4.7 ohms... this seems to me your gain will be 47.

Your PC output signal goes to 1 volt.... with your gain will distort...the maximum output power is obtained with 4 volts output (more or less)..... so....you have to multiply (gain) your PC signal by a ratio of four... and not 47.... your resistances must be 220 ohms and 56 ohms, or 220 ohms and 47 ohms.

This is your problem.... with 1 volt entering (alternated volts, audio volts) your circuit is trying to produce 47 volts...and this is not possible..so... too much gain means enormous distortion.

The problem is just this one...... i can be wrong about those resistances, but for sure the gain has some preset alike that one.

Search for datasheet and check your gain.... adjust it to 4 or 5....not more than that.

regards,

Carlos

wg_ski · 14th July 2008, 02:46 PM

TDA2002/2/4/5 have a really nasty habit of oscillating. Because the input is referenced to the same ground pin that carries high current, it's way too easy to have a bad layout. Not only do you need a star ground, but the resistance/inductance from the ground pin to the star ground needs to be minimized. If the chip gets hot just idling, then this is what's going on here. The output shunt cap does need a damping resistor, and it needs and ohm or two (not the usual 10 ohms). And be very careful where you "ground" it.

Tahmid · 14th July 2008, 05:21 PM

Thanks everyone,
I'll try your suggestions out and post the output.

13th July 2008, 02:01 PM	#1
Tahmid diyAudio Member Join Date: Jun 2008 Location: Dhaka	Help with TDA2003 amp Hi, I just made a TDA2003 amp for my PC. I set the gain resistors at 4.7 ohm and 220 ohm. When I plug in the audio source, there is too much distortion that the actual music can barely be heard. I am running it from a 12v 4a power source i built myself. What could be the reason for the distortion? What can I do to remove it? I thank you in advance for any help i can get. __________________ The tallest building in the world starts from the first brick. পৃথিবীর সর্বোচ্চ দালানও প্রথম ইট বসানো থেকেই তৈরি হয়েছে।

13th July 2008, 02:14 PM	#2
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	post the circuit and values you are using. Andy __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

13th July 2008, 02:57 PM	#4
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	why did you not use the circuit in the application notes? http://pdf1.alldatasheet.com/datashe...S/TDA2003.html Andy __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

14th July 2008, 12:46 AM	#6
destroyer X diyAudio Member Join Date: Feb 2004 Location: Recife - Brasil Northeast	The gain is too much high.... if i can remember the gain is the division of two resistances.... and you have 220 and 4.7 ohms... this seems to me your gain will be 47. Your PC output signal goes to 1 volt.... with your gain will distort...the maximum output power is obtained with 4 volts output (more or less)..... so....you have to multiply (gain) your PC signal by a ratio of four... and not 47.... your resistances must be 220 ohms and 56 ohms, or 220 ohms and 47 ohms. This is your problem.... with 1 volt entering (alternated volts, audio volts) your circuit is trying to produce 47 volts...and this is not possible..so... too much gain means enormous distortion. The problem is just this one...... i can be wrong about those resistances, but for sure the gain has some preset alike that one. Search for datasheet and check your gain.... adjust it to 4 or 5....not more than that. regards, Carlos __________________ Try to build an amplifier folks ... it is pure adrenaline!

14th July 2008, 05:21 PM	#8
Tahmid diyAudio Member Join Date: Jun 2008 Location: Dhaka	Thanks everyone, I'll try your suggestions out and post the output. __________________ The tallest building in the world starts from the first brick. পৃথিবীর সর্বোচ্চ দালানও প্রথম ইট বসানো থেকেই তৈরি হয়েছে।


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14th July 2008, 02:46 PM	#7
wg_ski diyAudio Member Join Date: Oct 2007	TDA2002/2/4/5 have a really nasty habit of oscillating. Because the input is referenced to the same ground pin that carries high current, it's way too easy to have a bad layout. Not only do you need a star ground, but the resistance/inductance from the ground pin to the star ground needs to be minimized. If the chip gets hot just idling, then this is what's going on here. The output shunt cap does need a damping resistor, and it needs and ohm or two (not the usual 10 ohms). And be very careful where you "ground" it.

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