Long long ago,I was very interested electronic making.my first chip amp used TDA1521 from philips company ,I don't know they still sell this chip or not.I know they can deliver out about 12W/8ohm ,I made PCB myself,use knife cut,So difficult.when I heard the song from thus simple amp and simple sound box,I was indulged in joy over my success.I mad lots of amp use TDA1514,more powerful than TDA1521,excellent sound.due to this reason I think Philips AMP IC of the best choosen for fans at that time.
When NXP class D IC were selling,I buy some TDA8922 ,test it performance once and again,burn lots of times and success many times.I believe it at last.
TDA8920 not stable when was sold just Start,this condition changed late 2008 ,more and more type mass product by NXP.50W/ch to 100W/ch to 150w/ch to 210w/ch.
I never believe the value at 10% THD,useless for any AMP.Maybe used in Guitar effector!for professional AMP 1%THD is able to accept.for Hi_Fi AMP you only believe ≤0.5%THD value.
TDA8920BTH works at 0.5% THD,only supply ±20V dc,higher voltage on it will get more power,but more harmonic out at speaker binding.
Good PCB routing will get better sound and stable work,you'll find IC hot and bad PWM wave out if route error.
TDA8920 have good tone color,clear warm powerful，class T AMP have excellent treble,poor bass.
Many people like TRIPATH TA series AMP,some friends asked for me develop a Hi-FI product include USB DAC+class T amp+SMPS,I promise them ,I'll finish this work Feb. 2010.
If any friends like ,Please give me some good advice,I'll send 5PCS AMP as present to 5 friends when finish.Chinese New Year coming!Happy new year!
When NXP class D IC were selling,I buy some TDA8922 ,test it performance once and again,burn lots of times and success many times.I believe it at last.
TDA8920 not stable when was sold just Start,this condition changed late 2008 ,more and more type mass product by NXP.50W/ch to 100W/ch to 150w/ch to 210w/ch.
I never believe the value at 10% THD,useless for any AMP.Maybe used in Guitar effector!for professional AMP 1%THD is able to accept.for Hi_Fi AMP you only believe ≤0.5%THD value.
TDA8920BTH works at 0.5% THD,only supply ±20V dc,higher voltage on it will get more power,but more harmonic out at speaker binding.
Good PCB routing will get better sound and stable work,you'll find IC hot and bad PWM wave out if route error.
TDA8920 have good tone color,clear warm powerful，class T AMP have excellent treble,poor bass.
Many people like TRIPATH TA series AMP,some friends asked for me develop a Hi-FI product include USB DAC+class T amp+SMPS,I promise them ,I'll finish this work Feb. 2010.
If any friends like ,Please give me some good advice,I'll send 5PCS AMP as present to 5 friends when finish.Chinese New Year coming!Happy new year!
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From the spec sheet, these specific NXP Class D integrated amps don't seem to be designed for very high quality audio.
However, if you get clearly audible distortion at higher supply voltages, i suspect you are doing something wrong somewhere. According to spec they should perform free of obvious distortion (<0.5% THD) at ANY allowed supply voltage up to a specific output power, i'm looking at fig. 22 in the spec. If this is not so, you might have a thermal problem - make sure that the heat conduction to heatsink is excellent. Or there is a problem with output chokes - make sure they don't get too warm. Or there is some other instability, the mechanism of which i cannot possibly guess.
The 10% THD values only come about when the output amplitude is higher than the input voltage minus internal voltage drop. This is a conventional figure used by amp makers which allows them to exxagerate power ratings for a given voltage by 20%, but this has no effect on actual THD.
However, if you get clearly audible distortion at higher supply voltages, i suspect you are doing something wrong somewhere. According to spec they should perform free of obvious distortion (<0.5% THD) at ANY allowed supply voltage up to a specific output power, i'm looking at fig. 22 in the spec. If this is not so, you might have a thermal problem - make sure that the heat conduction to heatsink is excellent. Or there is a problem with output chokes - make sure they don't get too warm. Or there is some other instability, the mechanism of which i cannot possibly guess.
The 10% THD values only come about when the output amplitude is higher than the input voltage minus internal voltage drop. This is a conventional figure used by amp makers which allows them to exxagerate power ratings for a given voltage by 20%, but this has no effect on actual THD.
I can't believe up theory,TDA series from NXP run low frequency about 330Khz,But I compare other Self Oscillate Class D(like IR series ),feel good than other.Every success product will far away from truth if you only believe the data from lab .We should try it many time in reality world,and not believe anyone say it should how value!if you learn THD where come from ,when you know what it EMI,when you know dV/dT what means.We should talk about some data from ourselves test.
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