• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Ideas for ground plane/shielding?

hotbottle

Member
2008-03-16 6:31 am
I just wanted to kick around some ideas for construction of tube amp projects. I have nearly always used metal chassis/boxes, but I am thinking of other materials, like wood, but then, how would I shield the circuitry?

One idea I have seen used, is to line the wooden case with aluminium foil, all glued on. Works, but is messy and can be damaged if scraped. Metallised cardboard would be nice, but I don't know where to get any.

I once used aluminium seet metal to construct and inner metal half-shell, inside a nice looking plastic instrument case. That works but is a lot of effort.

What about conductive paint? I seem to recall it's fairly expensive. Any cheap alternatives?

How about blank one-sided copper-clad circuit board? You could easily punch holes through it for tube sockets, and you could solder tag strips etc, directly to it on the copper side, then do point to point wiring from the tube socket to the tagstrips. The circuit board would make a good ground plane / shield.
 
hotbottle said:
How about blank one-sided copper-clad circuit board? You could easily punch holes through it for tube sockets, and you could solder tag strips etc, directly to it on the copper side, then do point to point wiring from the tube socket to the tagstrips. The circuit board would make a good ground plane / shield.


This is exactly the idea I have been kicking around myself, and if you used double-sided boards you could use the sides on the inside of the amp for the ground plain and the sides on the outside would be shielding.

-Justin
 

hotbottle

Member
2008-03-16 6:31 am
Well, the aluminium chassis I have used don't do much magnetic shielding,and they work OK, so it probably isn't necessary.

I have been looking around, and although copper tape isn't so easy to get, I have found lot's of aluminium tape. It's used for insulation, lagging, ductwork, sheet metal repair etc. and comes in rolls with good width. I think it may be a good choice.