Is There A "Best" Grounding Method?

[frankie5fingers]

Ground loop(s), using the enclosure (only), local ground plane, separate DC and audio grounds... Lots of discussions.  As a relative newb, I've used the tip and sleeve connections and star grounding.  Is there something that definitively reduces hum/noise more effectively than another?  Of course, that brings up another question...is there any value to shielding the enclosure or is that just belt and suspenders?  Thanks.

[alanp]

Grounding is a massive issue in some amplifiers(check out the Larry Grounding thread on Metroamp), but I can't say I've seen any debate on the topic in pedal forums.

[frankie5fingers]

I haven't either; but clearly there are a couple of ways to accomplish it.  I'm curious whether one method produces any less noise, or is more "reliable" or any advantage for that matter, over another.  Then of course, there's the idea of shielding and whether it has any advantages.  There isn't a lot of noise anyway, especially with the ability to tweak components to reduce certain types, but I was reading something from Lyle Caldwell regarding his method of grounding and it just got me thinking.  I'm not looking for a debate, just curious.  Thanks

[stecykmi]

I would say that it's not so important for most effects. in general, it's more of an issue for stuff with an on-board power supply.

[PerS]

Hi

This is an interesting question that I like to learn more about. So I give my comment just to keep discussion going... free to comment and criticize...

A year ago I re built my pedal board. I did it because I had problem with both hum and noise At the same time I also built three pedals – one looper, one FatPants and one "transformer". I think the two crucial parts was the looper and the "transformer", but they become a bit of the lead star how I will build my pedal in the future, if you guys not tell me otherwise.

In my post – http://www.madbeanpedals.com/forum/index.php?topic=4476.0, I show the looper inside, this:



I think this was important for the grounding om my board. It is the connection point between two loops and connect in and out. The shielded wire is not because it is necessary, its for grounding. I had them before and it had a good shield. All ground wires are connected to the horizontal wire just underneath the purple and the green at the bottom end. Another important part is that the box is only grounded in one place, the in jack on the left through the spring washer, that gives a real good connection. All the other jacks are insulated and are only connected in one point.

The other important part was to kill the suspected ground loop between my pedal board and my rack with POD, amp and mixer. I got my hands on a Lehle transformer and used it. From start I was going to build a small op amp driver in front of it. When I tried it it worked great in passive mode. I also added a direct out and can switch the output phasing.


   
Really neat little box, always in.

As I was on the go I also built a FatPants booster, really good pedal use it both to push my amp and pedals and to boost soloing. A must have pedal.





Here you can also see the same construction as for the looper, one grounding point to the chassis, the other is insulated. The grounding point for all internal parts is the little black wire below the foot switch. Connects the ground from power supply jack, from the in and out and the grounding from the FatPants.

Don't know it its a coincidence of my rearrangement or if this was a key to killed more or less all noise and hum in my setup. I think/whant to belive that the main parts is the grounding inside the looper and my Lehle-transformer. The FatPants was just for fun...;-).

//Per

[vvangelovski]

With most input/output jacks I've seen used in diy pedals, whichever method you use will end up with the metal enclosure being "grounded" when there's a cable connected to the input jack. Effectively the battery negative pole, supply negative pole, instrument cable sleeves, circuit ground and metal enclosure being at the same electrical potential - same point in the circuit. If you test for shorts between any of these points you'll see they are in fact shorted. Sorry for my lousy english.

As for the need for metal enclosures. You need some kind of shielding especially with the dirtbox circuits. This doesn't necesserally mean you need a metal enclosure, it could be a wooden or plastic box, but shielded inside (or outside) with a foil of some conductive material. A metal enclosure or shielding foil in a non-metal enclosure acts as a Faraday cage. This stops electromagnetic interference from getting inside the box and being picked up and amplified by a high gain circuit. I've had distortion circuits pick up my heartbeat, even radio transmissions from halfay around the world when testing them outside an enclosure, but they've worked without any noise inside the enclosure.

[frankie5fingers]

Thanks for your thoughts on this.  I like the idea of something (other than the jack to metal connection) secured to the enclosure.  What about additional shielding?  I once painted a FF enclosure with shielding paint and tried the circuit first in a bare metal box while the other box dried... a couple of hours between listens at most.  Frankly, I didn't hear any difference.  What's the conventional wisdom on shielding?  Thanks

[stecykmi]

conventional wisdom on shielding is to do it! ideally so that it completely surrounds the circuit. unsurprisingly, guitars can benefit a lot from shielding the control cavity too.

[vvangelovski]

A metal box is already shielded, especially an aluminium box. No need to do much else to it. If the circuit inside picks up noise it's most likely coming from the power supply or the guitar.