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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage

Post Subject: Shakey DIY BasicsPosted by Paul S on: 11/26/2011

How do I hate DIY? Let me count the ways...

Is there some reason you cannot make through-holes to facilitate soldering leads to your copper sheet? Use a hot iron (800 F) and plenty of aggressive flux to pre-tin the holes... Stand parts on short leads or use little blobs of removeable Si caulk (like GE marine grade). Do not let parts (other than ground leads...) touch that copper sheet... Cross various wires at right angles, as much as possible... Solder relevant parts directly to each other and to tube pins whenever possible. I don't remember from the pictures if your box has a steel bottom under the copper "ground plane", but it should. I also don't remember how you mounted the tube sockets; but it has to involve some parts floating well away from your copper sheet, in any case (not that this in itself should be a problem...).

Again, no way to over-stress this: Divorce all shielding - including the 6-sided box - from the copper sheet/ground plane... Drain the only the shields (including the boxes), to a (grounded) water pipe if you have to, anything with lower resistance than a "field discharge" via the circuit ground/house neutral...

I have used plenty of low-level gain stages without hum, despite parts that float well away from the "ground plane" (in my case, IC board or ground bus). A decent steel box with proper grounding, and covering un-used inputs and outputs, should be proof against external problems. AGAIN, physically and electrically isolate the copper sheets from the boxes! The sorts of problems you are talking about rather suggest an inside job...

Consider a DACT or Tent PS...

Best regards,
Paul S

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