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Angaria  
#1 Posted : Thursday, May 24, 2007 8:23:44 PM(UTC)
Angaria

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I picked up two populated revC boards - but I haven't found explicit assembly instructions, so I was hoping someone could tell me how to complete the final hookup - please check out the pics.

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Suggestions for what transformer to use for this?
Haven't built an amp before, so just want to be cautious about this - is it safer to house this in a metal chassis as opposed to a wooden one? Thanks.
Brian Donegan  
#2 Posted : Friday, May 25, 2007 4:28:12 AM(UTC)
Brian Donegan

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Most important, before you power it up, even for a minute, make sure that the LM3886 chip is attached to a heatsink with thermal compound. If not, your RevC will have a short life.

You want a 24-25V dual secondary or 48-50V center tapped transformer. You can either use one per channel, or a single larger transformer shared by the two channels. If you want to keep it simple, just go with a single transformer. Here are a couple recommended models:

Avel Lindberg from Parts Express
Antek (check out the AN-4225)

For transformer hookup, you want to turn the two center d=secondary leads into a centertap. Fot the Avel, tie the Red and Orange leads together, for the Antek, tie the two middle (adjacent) blue and green leads together. In both cases, you will be left with three secondary connections. The center tap you just formed will be the power ground connection, and shoudl attach to your 'C' wire. The other two connect to your 'A' and 'B' wires.

Your 'D' wire is the speaker output (Green is +, Yellow is -). Connect these to your speaker connector and nothing else.

Your 'E' wire is your signal input (Blue is +, Yellow is -). Connect these to your RCA input connector and nothing else (Blue to center pin, Yellow to shell, and make sure the connector is isolated from the chassis).

Let us know where you are (country) so we can talk about mains power wiring (120 or 240V).

This shoudl get you going. Metal or wood are both fine. Metal will offer more protection from RF interference, but that may not be a problem. If wood is easier for you, I would use it. There are things you can do to shield it later if needed.
Angaria  
#3 Posted : Saturday, May 26, 2007 9:43:08 AM(UTC)
Angaria

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Hi Brian - thanks for your detailed response! I'm in the USA. I'll get started wiring this up.
Dougie085  
#4 Posted : Tuesday, January 22, 2008 1:38:46 PM(UTC)
Dougie085

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Is 30VAC too much? I have some large heatsinks I plan on using with them and the transformer I have is 30VAC 300VA.
Brian Donegan  
#5 Posted : Tuesday, January 22, 2008 2:07:31 PM(UTC)
Brian Donegan

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Dougie085 wrote:
Is 30VAC too much? I have some large heatsinks I plan on using with them and the transformer I have is 30VAC 300VA.


Yes, 30VAC is too high.
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