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Class D Switching Power Amplifiers and Power D/A conversion

Will any of the D-amps run on 500ma?
Will any of the D-amps run on 500ma?
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Old 20th September 2016, 10:33 PM   #1
m0b1liz3 is offline m0b1liz3  Australia
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Default Will any of the D-amps run on 500ma?

I have a guitar pedal board power supply that has a 12v and 18v at 500ma. I was thinking I could put a low power Class D amp into a pedal if I could get it to run at 500mA instead of 2-5A.
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Old 20th September 2016, 10:48 PM   #2
easp is offline easp
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Maybe try a PAM8610, or a PAM8404/6 with a buck-converter? Boards are cheap on ebay, $1US, or less.
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Old 21st September 2016, 02:38 AM   #3
m0b1liz3 is offline m0b1liz3  Australia
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Never used a buck converter but like the idea. Question is if I can fit both into a pedal enclosure.
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Old 21st September 2016, 04:07 AM   #4
m0b1liz3 is offline m0b1liz3  Australia
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Is there a simple equation to figure out the voltage at 2A if I am using a buck converter with 18v 500mA input?

Also, are there other low power amp boards less prone to noise? I read a few threads about noise with PAM versions.
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Old 21st September 2016, 04:48 AM   #5
DownSouth is offline DownSouth  Mexico
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P = I X E
Power = current times voltage.

So 18v @ 500 ma = 9 watts.
so 9 = 2 times ? drum roll please 4.5 V Close to USB spec.

Buck converters are ~ 85% efficient so use 9 X.85 for watts out. 7.7 watts.

A class D audio amp is 80-90% efficient so you can get 5 watts of audio out which should be enough.
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Old 21st September 2016, 05:56 AM   #6
theAnonymous1 is offline theAnonymous1  United States
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Just get any board that can take 18V like TPA3116/8 and limit the gain. You should be able to get around 2W (1W per channel) with 8ohm speakers. That's enough for casual listening if the speakers have decent efficiency.

EDIT: It might be difficult to fit one of those boards in a pedal. Maybe this combo instead...

https://www.aliexpress.com/item/HT68...572143474.html
https://www.aliexpress.com/item/DC-D...636482278.html

Last edited by theAnonymous1; 21st September 2016 at 06:24 AM.
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Old 21st September 2016, 11:36 AM   #7
lutkeveld is offline lutkeveld
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Quote:
Originally Posted by theAnonymous1 View Post
Just get any board that can take 18V like TPA3116/8 and limit the gain
Or just use the Plimit function
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Old 21st September 2016, 10:15 PM   #8
Pafi is offline Pafi  Hungary
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500 mA of average current is enough for a very high volume with audio signal and a real speaker, if you somehow provide also the high peak currents. How? With a big capacitor, and maybe with a current limiter between PSU and cap if the PSU cannot handle overload properly. No need to limit voltage this way.
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