Power Supply for Class D: 12V AC

mulluysavage · 16th January 2011, 12:57 PM

Hi,

I am learning diy audio, and my current project is designing an amp for a friend and plan to use a pre-fab PC board that takes 12V AC and outputs 2 channels at 100W each. I am trying to find/make a decent power supply. Can anyone make any recommendations and/or direct me to readings on *AC* power supply design for audio?

mastodon · 17th January 2011, 11:09 AM

So, let me get this straight: input is 12VAC, and output is, what? 12VDC @ 100W?

DF96 · 17th January 2011, 12:04 PM

Does the PCB take 12V AC from a transformer? If so, you just need to safely wire a transformer. This would need quite a high current to supply two channels of 100W even for Class D: 20A in total? You would probably need a 400VA transformer.

100W seems a bit high for a first amp, unless you are just wiring together boards designed by other people. Even then it is risky - better to start at much lower power, especially if someone else is relying on you.

mulluysavage · 17th January 2011, 10:33 PM

Yes, board is pre-fab, 100W/channel, and they say it takes 12V AC in. Thanks for the tips about being responsible for another's amp, I want to make sure I do it 1. safely, and 2. so it sounds good. What about isolation? Clean sound?

mastodon · 18th January 2011, 09:54 AM

Quote:

You would probably need a 400VA transformer.

So that's essentially all you need. And some net entry, fusebox and any protection stuff you might fancy.

DF96 · 18th January 2011, 11:16 AM

You need to do some reading about mains safety in power supplies, as the mains side is the only thing you need to think about. Everything else is already decided by the amp modules you have chosen. Actually, not quite, you also need to learn about grounding.

Doing it this way you immediately have to do the two areas which can cause the most grief to newbies: safety and grounding. Not the place I would have started.

16th January 2011, 12:57 PM	#1
mulluysavage diyAudio Member Join Date: Oct 2010	Power Supply for Class D: 12V AC Hi, I am learning diy audio, and my current project is designing an amp for a friend and plan to use a pre-fab PC board that takes 12V AC and outputs 2 channels at 100W each. I am trying to find/make a decent power supply. Can anyone make any recommendations and/or direct me to readings on AC power supply design for audio?

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17th January 2011, 11:09 AM	#2
mastodon diyAudio Member Join Date: Jan 2011	So, let me get this straight: input is 12VAC, and output is, what? 12VDC @ 100W?

17th January 2011, 12:04 PM	#3
DF96 diyAudio Member Join Date: May 2007	Does the PCB take 12V AC from a transformer? If so, you just need to safely wire a transformer. This would need quite a high current to supply two channels of 100W even for Class D: 20A in total? You would probably need a 400VA transformer. 100W seems a bit high for a first amp, unless you are just wiring together boards designed by other people. Even then it is risky - better to start at much lower power, especially if someone else is relying on you.

17th January 2011, 10:33 PM	#4
mulluysavage diyAudio Member Join Date: Oct 2010	Yes, board is pre-fab, 100W/channel, and they say it takes 12V AC in. Thanks for the tips about being responsible for another's amp, I want to make sure I do it 1. safely, and 2. so it sounds good. What about isolation? Clean sound?

18th January 2011, 11:16 AM	#6
DF96 diyAudio Member Join Date: May 2007	You need to do some reading about mains safety in power supplies, as the mains side is the only thing you need to think about. Everything else is already decided by the amp modules you have chosen. Actually, not quite, you also need to learn about grounding. Doing it this way you immediately have to do the two areas which can cause the most grief to newbies: safety and grounding. Not the place I would have started.

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