A is the one I would use.

Thats great you are getting this thing going RDV!  I can't wait to see some pics of it all together.

AC doesn't have negative and positive.

I used an old CB base station enclosure for my LM3886 amp :-)

Funky heatsink, where did you get it?  How did it go together for you?  Pretty easy?

Looks great so far, I can't wait to see it finished and see how you like it.

I'm confused I guess.  If it is 24v+24v then it will put out too much power (24x1.4 = 33.6v), but if its 17v+17v @ 1amp, the voltage would be fine and the amperage too small.

Its possible to hit 30w RMS with these chips, but only at their very max limit.  You will want a 18v+18v with 100VA or better transformer.  18v+18v will give you a solid 25w of output.  If you are curious, you should really look at the datasheet.  It's in the wiki on the contents page.

WOW!  Looks great!  So did you build that all yourself?  Is it a kit?

Tranformers are always AC out.

It seems the preamp is good, so don't totally start from scratch.  Just do a new PS and power amp section, those are the easiest to build anyway!

Actually, DC makes very little noise compared to AC where it shouldn't be.

Insulation thingies?  I would say try changing your diodes.  If its not that, there is a good chance its a poorly made/old/worn out transformer.  Have you tried checking the voltage on the transformer with a good digital multimeter?  If it fluxes, even 0.01volts, thats a bad sign.

The diodes would be fine.  On that same note, 4700uF caps should be fine.  If you are worried about it at all, you can parallel caps of the same value with them like you asked.  It won't hurt, and it *might* help.

I would consider larger filter caps on your PS section.  Some amps just come with crappy small ones, I know you already replaced them, but if it was me, I would try replacing them with ones double in value or so.  How many amps is it?  I'm assuming the 212 means 2 x 12 speakers not the wattage.  If it is upwards of 100w RMS, I would consider two 10,000uF caps on the PS section along with new diodes.  Also, it might be a poor ground somewhere in the amp, double check that all connections are good, no cold solders etc.  Also see if there are any wires for sound (input etc) going near the PS, that will make it hum like a bumble bee.  Some amps just have poor design out of the factory, not sure if this is one of them.

I would assume that the red dot side is primary...but its not a good idea to assume when you are dealing with more than 9volts lol.  RDV, chris?