24V DC amp powered by PC's USB Hub?

[rbtqt]

Hi all,

 

Not sure where to put this question but here goes.

 

I want to power my 24V DC stereo amp using my PC's USB ports using a step-up converter. Just wondering if there's any danger to my PC if I do this?

 

Thank you in advance for the responses!

[mariushm]

Yeah, there's a small danger you'll damage your usb ports.

 

The voltage on USB ports is too low at 5v to realistically boost to 24v with good efficiency. You also have too little current available.

 

Expect a maximum of 2A of current on one USB port (or 2A shared between two usb ports on the IO shield) ... that's 5v x 2A = 10 watts.

 

If you're boosting to 24v, you're probably gonna do it at around 85% efficiency at best, so only around 8.5 watts will end up to your amplifier. At 24v , that's 8.5w / 24v = 0.35A.

 

So you'll basically get maybe 2-3 watts on each channel, if your amplifier is stereo.

 

If it's a headphones amplifier that needs 24v but only needs a couple watts, then it's doable, but debatable if it's a good idea, because switching regular may introduce extra noise in the amplifier so you'd get less quality in your headphones.

 

[rbtqt]

1 hour ago, mariushm said:

Yeah, there's a small danger you'll damage your usb ports.

 

The voltage on USB ports is too low at 5v to realistically boost to 24v with good efficiency. You also have too little current available.

 

Expect a maximum of 2A of current on one USB port (or 2A shared between two usb ports on the IO shield) ... that's 5v x 2A = 10 watts.

 

If you're boosting to 24v, you're probably gonna do it at around 85% efficiency at best, so only around 8.5 watts will end up to your amplifier. At 24v , that's 8.5w / 24v = 0.35A.

 

So you'll basically get maybe 2-3 watts on each channel, if your amplifier is stereo.

 

If it's a headphones amplifier that needs 24v but only needs a couple watts, then it's doable, but debatable if it's a good idea, because switching regular may introduce extra noise in the amplifier so you'd get less quality in your headphones.

 

Oooh. Thanks for the input! Very enlightening. So glad I joined this forum

[RTX 3090]

I doubt a USB port will provide enough current. for a 50W AMP, you will need minium of 24V 2A, which is equal to 5V 10A, factor in inefficiencies, probably 12-13A, but this all depends on how much power your speaker uses, some decent speakers only use 3W, some subwoofers need 50-100W. If you attatch a picture of your speaker and amp, we can work the exact current out

 

eit : your motherboard will (hopefully) have over current protection, shutting down the entire system, or just the 5V lanes if it is over current. Also you can consider just taking power from the 12V molex connector, it can deliver much more power, and not as much of a different voltage, just 12-24V, some amps even support 12v natively

[VoidX]

@mariushm is right, it won't work. If you make a Type-C inverter that fully supports PD (expensive and complicated), that is an option, just not very viable.

 

@RTX 3090 is right, the 12V is a way. I actually power my dorm's audio from a cheap amp connected to a random PSU. The issue is that the output power will drastically drop on 12V, I'm getting 20 Watts with some skipping, when the amp could support 50.

 

Just by a cheap 24V supply, they're like $20.