Help! Need usb powered Amp.

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I need a stereo amp that can be used to drive two small speakers. I haven't found the speakers yet either. I know you need more info to help but I guess the only way to give more info is to explain the project.

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The pictures above are of a portable Xbox I am building for personal use and to sale. The pictures above is in its design phase and when finished the panels will be cnc cut out of aluminum. I currently have a headphone jack connected to the points on the motherboard that feed the A/V port but the board doesn't put out enough to get much volume from 40mm headphones. I want an amp that can drive the best headphones you can buy and small speakers but not at the same time. I can wire it so that it is either powered by the power coming from the wall outlet or usb, whichever is needed.

Any help would be much appreciated.

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well the xbox powerbrick has 12 v rail,
so tda 8560 comes into my mind.
exactly ment for 12v, and will deliver more than enough power to drive even big speakers.
parts count is minimum.
at low volume setting quality is pretty decent.

i think its the best solution for you.
it supports down to 2 ohms.
 
it is, 5v and MAX 500mA, with many USB connections only 100mA

you'll have a hard time doing a proper headphone amp, let alone one that 'can drive the best headphones you can buy' making such a statement i'm not sure you know what that means. the only way to do the headamp would be to use a switching convertor to spin you the negative rail, which kinda rules it out for very high quality and doesnt buy you any more power, just more voltage.

a speaker amp is simply impossible with these constraints. I get the feeling you have gotten ahead of yourself without doing early research properly...
 
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Ma bad I knew that was too strong of a statement. I really don't need to drive super high end headphones. I basically just want to drive some small external laptop style speakers and if I can do that then I can drive any headphone I would be using. I'm not that knowledgeable about audio but I'd like to learn. I bought a set of laptop speakers powered by usb that will work for this build but most consumer speakers like that are also fed the signal by usb and passed thorough a dac. I cannot find anymore that accept the analog signal from the headphone jack which is what I need because the Xbox does not produce a digital audio signal through usb.

I am basically trying to get the monitor to be a monitor with built in speakers. I did not buy a monitor with built in speakers because the ones I looked at had bad reviews for the sound. So what I need to find is either some short and wide or small round speakers that will produce acceptable sound and an amp to drive them that can be wired either by usb power from a usb charger port on the surge protector I installed in the case or another power source from within the case.

I found a 2x2w sure electronics amp but Idk if it's any good and I would rather use one with a nonvolatile chip (I think I used the correct term, I want volume to stay at previous setting). I am confident enough to attempt building one but I need to know which chips to buy for amp and push button volume control, schematics, and place to buy.

If you think the problem with monitors with built in audio is the speakers and not the amp I would even buy that and change the speakers out if that would be a suggested solution.

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why don't you just proble the +12 line of the powersupply and use the tda8560 chip i mentioned?
it can drive more or lass any headphone /speaker.
volume controll can be a simple pot, the amplifier in its basic form is like 10 components at maximum. Allmost as easy as it can be.
 
looks like
DyadUSB is based on the AS2002, highly power efficient, switching, stereo audio power amplifier from Audium Semiconductor,
is using the 5V from the USB to create a +-9Vdc supply to drive a bridged amplifier (4 channels for stereo). That would expalin the preference for 16ohms to 8ohms speaker recommendation.

But
2x 13W peak power output (8ohms)
may really be 6.5W into 8ohms.
 
looks like is using the 5V from the USB to create a +-9Vdc supply to drive a bridged amplifier (4 channels for stereo). That would expalin the preference for 16ohms to 8ohms speaker recommendation.

But may really be 6.5W into 8ohms.

i'm sorry, but how on earth does a convertor make 6.5W out of a 2.5W supply? they should patent that quickly!! surely you can only increase the voltage at the loss of current, overall power should remain the same minus losses from the convertor
 
The pdf states that average music power is many times lower than maximum output power.
I happen agree with this statement.
If they designed for an average to peak ratio of 20dB (130mWpeak from a 13Wpeak) amplifier and used a very efficient DC to DC converter to create the supply rails and used a very efficient switching amplifier then it is very possible that the 500mApeak supply @ 5V could maintain the average levels required and capacitor storage can then supply the peak power for the high current transients.

The pdf does state
DyadUSB is a USB powered stereo audio amplifier module; designed to be embedded in to USB speaker systems.
and that implies they are designing to suit the limitations imposed by the USB power.
 
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