Enclosure

[lynessmy]

What is the actual reason to mount pedal in conductive enclosure?

What if a conductive box with arcylic base?
or maybe 2 retangle aluminium plated with 4 pcb spacer (no side) at each corner, would it do the job?

Harmonns is difficult to find here or extreamly expensive if any...so i'm looking for a cheap and an easy to work on (less metal work) alternative.
I saw aluminium stud enclosure on GEOFx, any other suggestion?

[widdly]

The conduction provides shielding from noise. 

You can use a plastic box and glue tin foil all around on the inside.

[axg20202]

Correct. Although to provide good shielding, the enclosure usually needs to be grounded. As long as the sleeve of one of the sockets contacts the conductive part of the enclosure, you should be fine.

[smnm]

OKW distribute Teko boxes from Italy worldwide - they are folded aluminium, so not as sturdy as cast boxes, but good for the price
see http://www.okwenclosures.com/contact/okw-global.htm

here's the range from the UK site
http://www.teko.co.uk/enclosures/alu-boxes.htm

They send free samples too if you want to check them out

There was another thread like this recenty and the consensus, surprisingly, was that sturdy plastic boxes are ok, shielding isn't such a big deal.
see http://www.diystompboxes.com/smfforum/index.php?topic=57812.0

[soggybag]

I read somewhere that the enclosure should either be grounded at a single point or not grounded at all. I don't remember there being being advantage to grounding the enclosure. why would that help?

Grounding at a single point would solve potential ground loop problems.

Not being grounded would also solve ground loop problems.

I would guess that a metal enclosure would act as an antenna picking up stray RF. Having an enclosure that was not connected to your signal ground would keep this out of your circuit.

[Beros]

I read somewhere that the enclosure should either be grounded at a single point or not grounded at all. I don't remember there being being advantage to grounding the enclosure. why would that help?

Grounding at a single point would solve potential ground loop problems.

Not being grounded would also solve ground loop problems.

I would guess that a metal enclosure would act as an antenna picking up stray RF. Having an enclosure that was not connected to your signal ground would keep this out of your circuit.

Well if you connect the enclosure to ground then the enclosure will work as a Faraday Cage and take all radio signals, electrical fields and that stuff and ground it so it shuts up.

Link: http://en.wikipedia.org/wiki/Faradays_cage

[Mark Hammer]

MANY commercial pedals are housed in plastic boxes and work just fine.  Metal chassis provide a certain "sonic insurance", but I put a lot of my pedals in plastic boxes and suffer no ill effects, noise-wise.  In my case, much of the interference comes from the fluorescent lights overhead, so I stick a piece of copper shim on the underside of the top half of the box, where my pots and switches can use it as a ground connection.  Here's an example:

The key factor to consider is how much gain there is in the circuit.  If it is fairly high gain, then more shielding is called for (as well as short leads) because you don't want to be amplifying nearby transformer hum 200x.  If the gain is reasonable or low, then minimal shielding may be necessary.  For instance, if it's a phaser, you have more to worry about from the FETs or LFO than you do from using a plastic box.

The other nice thing is that a plastic box lets you have positive OR negative ground in any box you want since the jack (even phone jacks used for power connections) isn't automatically tied to negative ground.  You can use one PS for your chorus AND your Fuzz Face.

People worry about plastic boxes not being as sturdy, but they can be VERY sturdy.  Just make a point of placing any stompswitches in a location where there will be less give to the box (i.e., closer to the edge).

[SGdan]

I want to try one of those cheap electric boxes that ive seen on here.  they look like theyre easy to work with.

[soulsonic]

I want to try one of those cheap electric boxes that ive seen on here.  they look like theyre easy to work with.

They're not. The stupid knockouts cause tons of headache. You end up having to do so much work to get them usable, it hardly seems worth it in the end. And the steel is very tough to drill. I got used to drilling being such a pain with the steel boxes, but then I was using some hammond type aluminum ones recently, and it was soooo much easier it almost felt like using plastic.

Plastic boxes are okay to fool around with when you're building something to experiment with, but I wouldn't be comfortable with most plastic boxes fpr any kind of serious professional use. There are some that are heavy duty enough to probably be okay, but they'd still have to be treated in some way for shielding. Mark's idea of using a piece of copper works good, but I'm really interested in experimenting with conductive paint - it looks very interesting, and I'd like to try it out inside some of my guitars too.

Shielding is absolutely essential. Grounding the shield is also absolutely essential. It's such an easy and effective thing to do, I don't see any reason why anyone would even consider not having at least some kind of shield.

[Pushtone]

That's brilliant how the pots ground your copper shield Mark.

No soldering and easy to take apart. Love it.

That looks so smart construction wise.

You've inspired me to make this next year my "plastic box" phase.

I'm so tired of shelling out the 15.00 for the alloy.

[Processaurus]

I read somewhere that the enclosure should either be grounded at a single point or not grounded at all. I don't remember there being being advantage to grounding the enclosure. why would that help?

Grounding at a single point would solve potential ground loop problems.

Not being grounded would also solve ground loop problems.

I would guess that a metal enclosure would act as an antenna picking up stray RF. Having an enclosure that was not connected to your signal ground would keep this out of your circuit.

Not grounding the enclosure makes it an antenna, it would actually be worse, noise and hum-wise, than having no enclosure.  As for the idea that grounding it at one point is a good idea goes along with the concept of star grounding, so that you don't have current running from a heavy current part of a circuit upstream from a sensitive part of the circuit.  However an enclosure, like a ground plane, has such a low resistance from any point to another, that it won't offer any resistance to things putting current on it from different points, especially tiny stompbox currents.

[Mark Hammer]

Conductive paint has its limitations.  Certainly you can't solder to it, which is one of the things I like about the copper shim I use.  It's a trivial matter to run a ground wire to the copper.  The other thing is that the paint seriously stinks and is the sort of thing you should really only do in a well ventilated area....which kind of eliminates winter building for some of us.  Finally, I don't know about you, but I'm never sure if the paint is thick enough to provide continuity.

I have a nice pair of Luxman stereo amps at home.  Not top of the line, but well-made and respected nonethless, and both have wooden chassis with some foil stuck to the inside as their shielding.  When you consider how much gain is required to turn a phono cartridge signal into some thing big enough to move a speaker, if foil provides enough shielding to do the job and keep noise out, then it's more than good enough for the inside of your pedals.

Companies like Rocktek use a metal insert that provides a shield for the copper side of the board.  My MXR Commande Series flanger is in a plastic box that is pretty much unshielded, and it's quite quiet.

[Dragonfly]

I want to try one of those cheap electric boxes that ive seen on here.  they look like theyre easy to work with.

They're not. The stupid knockouts cause tons of headache. You end up having to do so much work to get them usable, it hardly seems worth it in the end. And the steel is very tough to drill. I got used to drilling being such a pain with the steel boxes, but then I was using some hammond type aluminum ones recently, and it was soooo much easier it almost felt like using plastic.

The key to using them is to use the "cover" as the top of your stompbox, and drill into that. No knockouts there.

Still a pain in the ass though, especially when you can by a Hammond at Fry's for under $10, or one of the Taiwanese "Hammond style" enclosures for $4-$7