is lm3886 good for 50W sub?

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JAZZ2250 said:
Is it specifically designed for subwoofer amplifier or for general use? I tried LM3875 with XO frequency of ~100 Hz and I had whole lotta distortion. So, I switched to OPA549 and OPA541 using the following circuit. Any comparison of these two circuits available?

http://home.attbi.com/~greggbaker/invertedLM3875.gif


Hello jazz2250 - so witch one did You use - opa549 or 541 and did You use the same values for resistors, caps etc or modified sth??

Thx for replies!!
Greets.
 
PaulHilgeman said:
Can you just parallell them and make sure that they have the same input signal?

-Paul


At the very least, you'll need to load each module's output with well matched resistors so that they share the load relatively evenly 0R1 on each output should get you somewhere in the ballpark. You'll probably also need to give each module a servo to ensure that the DC output for each module is kept close to that of the other modules so that current doesn't flow between them and cause unneccessary heat generation. All of that can be achieved with very little circuitry and can be built to have minimal impact on sound quality.
 
mad_z said:

Hello jazz2250 - so witch one did You use - opa549 or 541 and did You use the same values for resistors, caps etc or modified sth??
Thx for replies!!
Greets.

I tried both. Well... I'm still trying both and have not decided which one to go.
I used 22k instead of 10k in order to reduce gain. My subwoofer has 50W maximum, so I didn't want to have too much gain.
Power supply capacitors I used are 10,000 uF on each side. They are mounted on the testboard of mine, so I didn't have a chance to try capacitors of other values. Actually, I'm not sure how much capacitance I should use in the final design.
I didn't use .22 Ohm resistor at the output. I think it'll make the sound muddy. Well...it's a personal taste. You can do some experiment with that resistor.
I didn't use 1 uF capacitor across the +/- power supply rail because amplifier module was very close from the power supply capacitors. In the final design, I might need to use 0.1 uF film capacitors from each side of power supply rail to ground.
Only one bridge rectifier was used instead of two as is in the figure.
Input capacitor is currently non-polar electrolytic, but I will replace it with a film capacitor.
I hope this helps.

A picture of my crude testboard is at the following link (post #18). Don't laugh, please. :)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=11931&perpage=15&pagenumber=2
 
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