Shielding isues with wooden box

[shawsofhell]

I currently have my effects all set up in a rack and then they are remotley triggered via a switching system I designed that allows me to assign patches to pedals.

I am currently converting this to a system where the switching and effects will be in a box at my feet which will look a lot like one of Pete Cornish's designs.

My question is how does he stop his designs becoming noisey when he uses a wooden box to house everything? Is there any type of shielding I could get (eg paint, foil) to put in such a box?

Thanks guys

[d95err]

Corhish alleggedly uses a "secret" shielding trick. Most likely it's some kind of shielding paint.

[darron]

magnetic paint, or aluminum tape are reported to work. i've never done it though. make sure there's a good continuity between all the shielding though otherwise it would be useless having it there.

[bancika]

there are several methods, arranged by price:
1) shielding paint
2) using self adhesive copper tape with conductive adhesive (available at stewmac.com), very nice but not cheap
2) using self adhesive aluminum tape
3) make DIY adhesive tape of aluminum foil and paper. I did this in my wooden enclosure and works like a charm.
You need piece of paper (A4 or similar), regular aluminum tape used in kitchen (here it costs about 1.5$ for 30m x 30cm roll). Cut aluminum to be little larger than paper, cover whole paper with glue and put aluminum on top. When it's set just cut excess aluminum and that's it. Use glue to fix it to wood. The only drawback is that you need to make it one piece (which shouldn't be a problem) because it's not too easy to make nice contact between two pieces. Do not cut out holes for jacks (cut others), just pierce it and squeeze jack in. When you screw jack tight it will make nice contact with aluminum shield. Of couse you need about 1-2mm wider holes for jacks then usual.
Cheers

[Mark Hammer]

I have two older Luxman stereo amps from back in the day when components were made in wooden cabinets rather than injection-molded plastic monstrosities.  In both instances the wooden half of the chassis is lined with an adhesive backed type of thick aluminum foil, with a screw providing the means for connecting a ground wire to that lining.  Works fine.

[shawsofhell]

Sweet thanks guys I'll have a look around for the paint or adhesive.

I post some picks of the project when I'm finished with some pcbs as well so others can get an idea of how to do something similar.

The specs will be:
8 effects all controlled by true bypass relays
1 external loop controlled by true bypass relay
cntrl outputs for switching amp channels
10 programs consisting of 8 patches per program for a possible 80 different combinations
manual mode for switching on effects individually
all controlled with a AVR micro

[Alex C]

Here's a thread with some discussion of Cornish boards:
http://www.diystompboxes.com/smfforum/index.php?topic=40418.0

and a link to a Cornish page on the making of Dave Gilmour's pedalboard:
http://petecornish.co.uk/bop.html

[darron]

I have two older Luxman stereo amps from back in the day when components were made in wooden cabinets rather than injection-molded plastic monstrosities.  In both instances the wooden half of the chassis is lined with an adhesive backed type of thick aluminum foil, with a screw providing the means for connecting a ground wire to that lining.  Works fine.

sounds like the underneath of many scratchplates/pickguards, or the back covers of guitars. have you ever noticed how often the foil isn't hooked up to ground? sometimes they are connected by a pot, but for things like the back panel they often aren't. hmm...

[GibsonGM]

My old '69 Melody Maker has a foil-backed plate...the electronics sit in a copper 'tub', if you can believe that! It has tabs that line up with the screw holes, and when you screw the plate to the body, voila, it makes contact.  Neat setup.

I use regular old aluminum foil for shielding...just glue it in with white glue.  You have to coat the inside of the box well, press the stuff in and smooth it, and be careful when putting your stuff in there so you don't pop a hole into it!   If you need more than 1 piece, you have to figure out a way to make them contact each other electrically...a PITA.  And....watch out that the wire terminals of pots don't contact the shielding - I wrap them with electrical tape so they don't ground out on it!   

[John Lyons]

Here's how I do it. There are some photos etc here: http://www.mrdwab.com/john/shielding.html

John

[R.G.]

Gosh, did anyone ever get a can of spray-on pressure sensitive adhesive and spray one side of a sheet of kitchen aluminum foil?

Wouldn't that make thick aluminum tape 12" wide?

[Barcode80]

the best diy shielding i have ever done was just some 3M spray adhesive and aluminum foil, with a screw in the wood to ground to. works like a charm!

[bancika]

Gosh, did anyone ever get a can of spray-on pressure sensitive adhesive and spray one side of a sheet of kitchen aluminum foil?

Wouldn't that make thick aluminum tape 12" wide?

I don't know about USA but here in Serbia aluminum foil is very thin which makes it virtually impossible to work with (cut, bend and glue). That's why I glue it to paper first and then use it...it's much better that way, and very cheap

[Joe Viau]

I remember on Lane Poor's web site that he had a tutorial on using brass foil.  It was adhesive backed and it was a lot of work, but the end result was great.  He was talking about shielding a control cavity but you can apply the same principles to a stompbox.  The Wayback Machine has the text, but no pictures:

http://web.archive.org/web/19990427135215/www.lanepoor.com/shield1.html

Couldn't you use sheet brass for a large enclosure?

[Rafa]

Aluminium foil from the kitchen has anybody tried??
Cheers
Rafa

[Gilles C]

I remember on Lane Poor's web site that he had a tutorial on using brass foil.  It was adhesive backed and it was a lot of work, but the end result was great.  He was talking about shielding a control cavity but you can apply the same principles to a stompbox.  The Wayback Machine has the text, but no pictures:

http://web.archive.org/web/19990427135215/www.lanepoor.com/shield1.html

Couldn't you use sheet brass for a large enclosure?

I began to use brass from a roll of brass (10 or 12" wide) maybe 10 years ago to shied the inside of the cavity and the back of the pickguard of my homemade Strat. And I then used it for the inside of some wood boxes I made for a couple of effects.

Like this one



It works very well. I used double side tape for that one, but I used contact glue for my guitar. And you can solder a ground wire very easily on that brass.

Gilles

[Barcode80]

rafa, i used regular old kitchen aluminum foil and the 3m adhesive when i shielded my guitar cavity. as long as you don't beat he crap out of it while you are applying it and make sure you apply it very smoothly, it looks and works magnificently. i've never had the problems of working with such a thin material that others seem to have had.

[idlechatterbox]

[Joe Viau]

That's great! All the foil reminds me of something from an old "Lost in Space" set!

[Joe Viau]

Oh, and Gilles, thanks for the reply and the picture.  I was distracted by a bright, shiny object (sic).