Connect the IC tab to ground very well, use heavy gauge wire.
And see what the data sheet says about THD specifications, I have a feeling this chip is noisier than the 2030/40/50 series intended for home use.
And see what the data sheet says about THD specifications, I have a feeling this chip is noisier than the 2030/40/50 series intended for home use.
Hey!
Yes, This was very very interesting experience for sure. I learned about troubleshooting these types of circuits, and even got some further ideas on how to improve a next version of the PCB. Thanks a lot for sticking to this thread while we did all this work!
I do have one last experiment I want to try without the op-amp to see if the op-amp is needed in every situation or just in this one.
Will report back when i have conducted that, will need some changes here and there first though.
Further, I really think to have a op-amp to act as a buffer for a chip like this makes a lot of sense. Even if it looks like on paper that you "should" be able to use a mp3 player output directly in to it, I really think that this could been the root cause of this.
As it was first after we got the op-amp circuit right, that we really got to see a major difference in the 2nd harmonic. (after the breadboard ground issues that is 😀))
Curious, do you have any information on if these chips are usually fed through a buffer or even a small pre-amp when they are used in a car-stereo system for example? I have no information on that, but I guess for example there would be a FM-tuner chip - pre-amp/buffer - TDA chip, or a similar setup?
Then it would make even more sense that this was actually our problem all along.
Yes, This was very very interesting experience for sure. I learned about troubleshooting these types of circuits, and even got some further ideas on how to improve a next version of the PCB. Thanks a lot for sticking to this thread while we did all this work!
I do have one last experiment I want to try without the op-amp to see if the op-amp is needed in every situation or just in this one.
Will report back when i have conducted that, will need some changes here and there first though.
Further, I really think to have a op-amp to act as a buffer for a chip like this makes a lot of sense. Even if it looks like on paper that you "should" be able to use a mp3 player output directly in to it, I really think that this could been the root cause of this.
As it was first after we got the op-amp circuit right, that we really got to see a major difference in the 2nd harmonic. (after the breadboard ground issues that is 😀))
Curious, do you have any information on if these chips are usually fed through a buffer or even a small pre-amp when they are used in a car-stereo system for example? I have no information on that, but I guess for example there would be a FM-tuner chip - pre-amp/buffer - TDA chip, or a similar setup?
Then it would make even more sense that this was actually our problem all along.
Hey! I actually attempted this early in the project, no difference unfortunately. However, if this package was laying down, having the tab soldered to the ground plane would maybe be an idea. Im guessing these are normally mounted to a heat sink in the car stereo, which in turn is chassis ground maybe?
Hi! Good to know that we could make progress!
I don't have specific information about the need of pre-amp.
In general, we use pre-amps if the signal to be fed to the amplifier is not high enough to achive maximum power, if the amp input impedance is to low to the source or if we need some kind of equalization.
TDA2004 input impedance is 70kohms (high enough) and gain is enough so I was suprised that you had that issue.
It should work without any pre-amp.
For my desktop PC, I use a similar, but better, integrated amp (TDA7265) and I feed it directly with the PC output.
During our conversation, I also measured the THD of it using a smartphone, just to in case, and there was no distortion.
I didn't use a PCB and just connect components by soldering them to each other (very ugly!) - but I used the concept of star GND.
As you said, now you've got exposed to all kinds of problems and also some tricks to resolve them.
Keep trying different layouts.