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Originally Posted by steinba
How far apart will the cards have to be to avoid interference/noise?
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As far as you can. You are almost entirely worried about magnetic field. It is complex, but as a first approximation you are looking at 1/(distance squared) for reduction of effect - once you get out of the near field of the transformer. But in truth I have a STEPS in a case that spends most of its life almost touching the PPA's case. There is no discernible hum or interference. Opposite sides a conventional sized HiFi case is more than adequate for all but the most obsessive. Then you do separates anyway.
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Should I shield the cards from eachother with a metal plate? (Copper?) |
Little point. There may be the tiniest bit of radiated hash from the PS, but the pretty careful design of the STEPS makes this very low. You can't shield the magnetic field except with Mu Metal. This is painful, and usually not needed. Distance is your friend.
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How do I cope with the different "grounds"? |
Complex, in a way. There is no ground on the STEPS, except for the power ground (earth) connection to the Y cap. This goes straight to the IEC plug. There MUST be a chassis ground, that is a separate connection from the chassis, directly to the ground connection on the IEC plug.
Don't let anyone dissuade you from this. Connect the signal ground in one place only to the case. For a conventional PPA build this is the connection to a bolt on the back of the ALPS volume control. This works well. Ensure you use insulated input and output connectors.
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Will it suffice to use a power LED and switch on the PSU end only? |
Depends how many LEDs you would like on the front. But yes.
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And lastly: Any enclosure recommendations? |
Zillions. Have a look at the sticky thread at the top with pics of builds. There are lots of PPAs - mostly in Hammond cases - but this isn't what you want, but quite a few other ideas. The Parmetals cases seem to have a good following. But there are as many possibilities as your imagination and patience will take you. (Wallet can take a beating too.)