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Audio Amplifier heads-up

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Feb 25, 2013 11:52 am Post subject: Audio Amplifier heads-up

I've been working with some interesting

audio amplifier modules with very attractive

pricing and performance numbers for the bux.



They're generally described as 5v powered and

will often cite the ability to run off the USB

port of a computer.



http://tinyurl.com/ag3dey2



http://tinyurl.com/bdkt495



http://tinyurl.com/a7gdp3h



These are 'class D' audio amplifiers (switch mode

power supplies that audio rate modulation

response). I've found that they generally perform

as advertised.



I've found that they're sensitive to the output

impedance of the power supply with respect to

internally generated white nose. Further, they're

not two whippy when it comes to rejection of noise

on the 5v line. Noises on a USB supply port

can vary widely from one computer to the next with

lap-tops being the least likely to offer adequately

conditioned power for these devices.



Further, loud passages in program material will drive

the amplifiers into unstable operation that cause

one to grate their teeth. I've found that a LARGE

capacitor (like 10,000 uF) really tames them down

. . . alternatively, an array of ni-mh cells floated

across the power line work just as well . . . and

makes the amplifier portable.



Just a heads up. Class D is one 'wave of the future'

for not-quite hi-fi audio applications. The prices

and performance are attractive . . . but there

are integration issues the user should be aware of.



If you are already, or plan to fiddle with

these critters, I'd be pleased to compare notes

either here on the List or privately.

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Feb 25, 2013 12:50 pm Post subject: Audio Amplifier heads-up

I've been working with some interesting

 audio amplifier modules with attractive

 pricing and performance numbers for the bux.



 [img]cid:7.1.0.9.0.20130225143836.010c1030(at)aeroelectric.com.0[/img] 



 They're generally described as 5v powered and

 will often cite the ability to run off the USB

 port of a computer.



  http://tinyurl.com/ag3dey2



  http://tinyurl.com/bdkt495



  http://tinyurl.com/a7gdp3h



 These are 'class D' audio amplifiers (switch mode

 power supplies modulated at audio rates).

 I've found that they generally perform as

 advertised. Very efficient. I'm presently

 listening to some ambient music at pleasant

 levels where the two speakers draw an average

 of 20 milliamps total at 4v (80 mW power input

 to the system).



 I've found that they're sensitive to the output

 impedance of the power supply with respect to

 internally generated white nose. Further, they're

 not too whippy when it comes to rejection of noise

 on the 5v line. Noises on a USB supply port

 can vary widely from one computer to the next with

 lap-tops being the least likely to offer adequately

 conditioned power for these devices.



 Further, loud passages in program material will drive

 the amplifiers into unstable operation that gives one

 pause for the gnashing of teeth. I've found that a LARGE

 capacitor (like 10,000 uF) really tames them down

 . . . alternatively, an array of ni-mh cells floated

 across the power line work just as well . . . and

 makes the amplifier portable.



 Just a heads-up. Class D is one 'wave of the future'

 for not-quite hi-fi audio applications. The prices

 and performance are attractive . . . but there

 are integration issues the user should be aware of.



 If plan to or already are fiddling with

 these critters, I'd be pleased to compare notes

 either here on the List or privately.



 

   Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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enginerdy(at)gmail.com
Guest

Posted: Mon Feb 25, 2013 1:51 pm Post subject: Audio Amplifier heads-up

Have you taken a look at the output RFI? Or is it reasonably well filtered in your test PCB? With the highly susceptible nature of some flying widgets, I'm curious what your take is.



Daniel





On Feb 25, 2013, at 2:46 PM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

[quote]  I've been working with some interesting

 audio amplifier modules with attractive

 pricing and performance numbers for the bux.



 <fd7795a.jpg> 



 They're generally described as 5v powered and

 will often cite the ability to run off the USB

 port of a computer.



  http://tinyurl.com/ag3dey2



  http://tinyurl.com/bdkt495



  http://tinyurl.com/a7gdp3h



 These are 'class D' audio amplifiers (switch mode

 power supplies modulated at audio rates).

 I've found that they generally perform as

 advertised. Very efficient. I'm presently

 listening to some ambient music at pleasant

 levels where the two speakers draw an average

 of 20 milliamps total at 4v (80 mW power input

 to the system).



 I've found that they're sensitive to the output

 impedance of the power supply with respect to

 internally generated white nose. Further, they're

 not too whippy when it comes to rejection of noise

 on the 5v line. Noises on a USB supply port

 can vary widely from one computer to the next with

 lap-tops being the least likely to offer adequately

 conditioned power for these devices.



 Further, loud passages in program material will drive

 the amplifiers into unstable operation that gives one

 pause for the gnashing of teeth. I've found that a LARGE

 capacitor (like 10,000 uF) really tames them down

 . . . alternatively, an array of ni-mh cells floated

 across the power line work just as well . . . and

 makes the amplifier portable.



 Just a heads-up. Class D is one 'wave of the future'

 for not-quite hi-fi audio applications. The prices

 and performance are attractive . . . but there

 are integration issues the user should be aware of.



 If plan to or already are fiddling with

 these critters, I'd be pleased to compare notes

 either here on the List or privately.



 

   Bob . . .   

[b]

- The Matronics AeroElectric-List Email Forum -

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ceengland7(at)gmail.com
Guest

Posted: Mon Feb 25, 2013 2:03 pm Post subject: Audio Amplifier heads-up

- The Matronics AeroElectric-List Email Forum -

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Feb 25, 2013 6:01 pm Post subject: Audio Amplifier heads-up

At 03:42 PM 2/25/2013, you wrote:

  	  Quote: 	
		  Have you taken a look at the output RFI? Or is it reasonably well filtered in your test PCB? With the highly susceptible nature of some flying widgets, I'm curious what your take is. 	


   Not yet. The current application is terrestrial.

   I will explore that characteristic in due course.



 

 

   Bob . . .    [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

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