class d usb powered amp?

[pekar]

I'm wondering if there's anything available that would run at USB (3.5-5.5V)
voltages?
As much as I love the 12 volt class d amplifiers, the ubiquity of USB
powered devices has me wanting to make even smaller systems.

Thanks,
Pekar

[richie00boy]

You can run from 5V - look at walkmans etc. You just need to rearrange the output stage to work at low voltage. The issue is the available current from USB is probably not enough to drive speakers safely.

[pekar]

I would use an onboard battery as well.

[OzMikeH]

USB power is often particularly noisy as well. Low voltage, mediocre current and the need for additional filtering would not make it worthwhile to me.

You could use USB with a step-up converter to charge a very small 12V battery when the amplifier is not in use.

[Saturnus]

The USB specification says 5 V and 500 mA max. So that'll only allow you to draw 2.5 W total for the amp. That's not an awful lot of power but it could be done.

[soongsc]

I actually have a USB class d dongle. A sample from a local company. They also displayed a board with 3 channel capability as far as I can recall.

[pekar]

Very interesting, the dongle is essentially what I'm after.
One configuration I've envisioned is a dongle that contained a sound card and a small amp as well that you could connect any speakers to.
I'm after cable reduction more than awesome sound.
I'd like to reduce the number of cables I have to plug into my laptop when I'm at my desk. The more externals that use USB the better, as I could plug them all into a hub and only have to connect one USB and power.