USB to power an amp?

samsagaz · 30th July 2012, 10:07 PM

Is possible to make an audio amp using power from USB? how much will be max output? :/

Regards

samsagaz · 30th July 2012, 10:10 PM

I think that USB use 5v and max is 100mA right? its just 0.5 Watts :/

N-Brock · 30th July 2012, 10:17 PM

nope, standard is 500mA but some allow more, (USB 3.0) and some ports like on the macbook air allow less current draw.

Ouroboros · 3rd August 2012, 01:55 PM

If you use an efficient Class-D amplifier with NFB, and partner it with a switch-mode dc-dc converter that alters its output voltage in response to the envelope level of the signal, you can use the fact that speech and acoustic music has a high peak-to-mean ratio. The output power of the amp + dc-dc converter will have a much higher peak power capbability than the simple USB power source would imply. Obviously you also need a large reservoir capacitor value.

There was a company pushing this approach strongly on here last year.

30th July 2012, 10:07 PM	#1
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	USB to power an amp? Is possible to make an audio amp using power from USB? how much will be max output? :/ Regards

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
usb power supply for audio	tze-hao yen	Power Supplies	1	19th June 2012 09:47 AM
USB Power Isolator	johnmarkp	Digital Source	2	24th March 2012 05:03 AM
usb power noise filtering	bmx	Power Supplies	19	16th May 2010 07:00 PM
USB power	musicfan_cbs	Digital Line Level	1	30th March 2010 10:06 PM
USB powered NOS USB DAC with built-in headphone amp	dsavitsk	Digital Source	15	10th August 2006 06:11 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

30th July 2012, 10:10 PM	#2
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	I think that USB use 5v and max is 100mA right? its just 0.5 Watts :/

30th July 2012, 10:17 PM	#3
N-Brock diyAudio Member Join Date: Oct 2007 Location: Cambridge, MA Blog Entries: 4	nope, standard is 500mA but some allow more, (USB 3.0) and some ports like on the macbook air allow less current draw.

3rd August 2012, 01:55 PM	#4
Ouroboros diyAudio Member Join Date: Dec 2003 Location: Nottingham UK	If you use an efficient Class-D amplifier with NFB, and partner it with a switch-mode dc-dc converter that alters its output voltage in response to the envelope level of the signal, you can use the fact that speech and acoustic music has a high peak-to-mean ratio. The output power of the amp + dc-dc converter will have a much higher peak power capbability than the simple USB power source would imply. Obviously you also need a large reservoir capacitor value. There was a company pushing this approach strongly on here last year.