TI TPA3100D2, Amazing Class D Amp

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I have been playing around with the Sure TPA3110 and TPA3122. Great little amps with a few simple mods they sound quite wonderful. :D

Here are the last 2 just completed. Comments would be most welcome ;)
 

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I was afraid someone would ask why I made the mods I did. :eek: Don't really know what I am doing here - it's a lot of guessing and experimenting for me although I do read all the forums that I can and slowly, slowly I'm learning. :)

wushulin- I tried a few different caps on the 3110 and these just seemed to sound the best.

keith- the mods on the 3110 are just the 2 film caps (Elna 2.2). On the 3122D2 I changed all the rail caps to 470uf 35V and the input caps to two 2.2 and one 1.0 Elna film caps.

Please suggest better improvements that I could try for future builds :)
 
I tried several different mods to the boards- especially the 3122. By replacing some caps then others until I found what sounded the best to me. On the first 3122 I tried I put some big caps on the rails and instantly blew the chip. I guess that comes with not really knowing what your doing :( The nice thing about mucking about with these things is that the are so cheep to by if you screw it up it's not such a big deal :)
 
after much thinking (wow smokey?) and playing with mine, I think I need to try a beefier supply than the 8 AA's I'm using now.

Also the great sound (when it's not making me angry, lol) may be due to the output not going through output coils, but then it should use only a few inchs of twisted spkr wire, unlike my 6' of parallel junk.

Isn't a 3122 basicaslly half of a 3110 ?
based on page 6 (on texas instruments data), you can't bridge a bridge amp............
http://www.ti.com/lit/ds/symlink/tpa3110d2.pdf

at 12v and 8ohms, I should be able to get 7 watts, and 4 ohms I should get 11.
(page 9 of the above pdf).
I ain't getting 11w, no way, no how, even 4.5 watts (we are not driving a resistor here folks).

I think 8 AA's can put out what, an amp? And that's not enough for 11 watts into 4ohms.....
12v into 4ohm = 3amps, 8v (subtract for .707) into 4ohms still would be 2amps (that 8 AA's can't deliver).

Am I off base ?
I am pretty new at this class D stuff..........

Norman
 
The TPA3110D2 is just screaming out for input transformers. Both + & - inputs for each channel are biased at +3V, so an input transformer could be connected directly without any coupling caps. You also don't need to trade off LF extension against charging time to keep pops away. I suspect that the transformer would also reduce any RFI interference on the input signal by acting as a low pass filter (very relevant if you use an SMPS in the same chassis). I've ordered two boards and have plenty of 600:600 transformers that will do for testing the theory :)
 
The TPA3110D2 is just screaming out for input transformers?

I guess things depend on your design, when you say this part needs a I/P transformer. I believe that it is an unnecessary expense.
I have been using this part capacitor coupled, SE, for 2 years now and it is a very well behaved part.
I would not be hooking up my best speakers to it until I was sure that this part would not fry them or had annoying pops.
These pops you speak of, could be coming from ckts up the signal chain and the transformer will do nothing to prevent it.
I use the enable pin as well, since I shut it down when I am powered from USB.
I have tried transformer and SM external supplies and have no issues.
I use a 1uF/50V/X7R/1210 coupling cap. You could get silly and use a film cap but it I doubt that you would hear the diff in a listening test or with the analyzers.
 
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