Super n00b question on grounds

[alphadog808]

Hey guys,
   I'm new to the scene and wondered something about pedal grounding.  I only realized now  that if I hook up a ground to the sleeve lug of the input or output jack the whole enclosure becomes a ground as the jack sleeve touches the enclosure.  With that being said, why do most schematics have both input and output sleeves grounded via wire? 

It would seem once you ground one jack, the other jack(due to the enclosure) gets grounded as well, so there's no need to run that second ground. See pic below.

BTW, I understand that this is all moot if your enclosure isn't metal. 

I just wonder about stuff like ground loops as this is my 5th pedal and they all whine/d.  I'm beginning to wonder if something I do in my wiring set up is causing this.  Currently I tap the ground wire from the 9v connector and feed it to a small piece of vero that has a bunch of wires connected to it; essentially giving me multiple ground wires that I can run to the jacks, lugs, etc.  I think this ok, but I wasn't sure.  I figured if the enclosure is grounded, I can eliminate the ground going to the other jack.

[JustinFun]

The trouble is that jack sockets can easily become loose - if you're relying on the enclosure for your output lack ground then you're risking a live band situation where the whole guitar signal fails whether in bypass or 'effect on' mode. Result = your name is mud on the local music scene.

For me, that outweighs any ground loop considerations. Personally I star ground to the enclosure and use plastic jacks for in and out. Don't know if that's the best approach - there are others here much better qualified to comment - but it works for me.

[Liquitone]

It took me a while to figure this out as well, but the ground between the two sleeves is indeed grounded through the enclose and the wire isn't needed.
I believe a wire there could even cause ground-loops. I do wonder about that putting all your grounds only to the dc jack, you can still just use the ground lugs on your jacks to connect all the grounds of your circuit.
I never had any problems with jacks coming loose and causing grounding issues.  I use Neutrik open jacks, which are pretty reliable.

[alphadog808]

Great, thanks guys! 

[GGBB]

As Kay said, jacks coming loose is rarely a problem.  Even if they do, the likelihood of completely losing contact is very small as for this to happen the jack would have to be either suspended in mid air within the enclosure hole, or resting only on the finished surface of the pedal and not touching any part of the bare enclosure.  The force of gravity on the cable usually prevents that.  If you are worried about this, scrape/sand/file away the paint from the edges of the hole - particularly the bottom part where gravity pulls the jack down.  And even if one does come loose, it's a quick easy fix.

[mremic01]

I only ground the input jack via wire and let the output jack get grounded through contact with the enclosure. I've never had any reliability issues because of this, and one less wire keeps the insides that much tidier. No matter how loose a jack is, it always seems to be making contact with the enclosure somewhere. I'm much more concerned about the tip part of the jack grounding out on the enclosure or on a pot case.

I'm not sure why all your pedals whine. When I started out, I ran a ground wire to both jacks and none of my early build had that issue. If you're not already doing so, it's a good idea to run a jumper from the effect input lug of the 3PDT to a lug that is grounded when the effect is bypassed. Sometimes not grounding the input can cause oscillation that bleeds into your dry signal when the effect is off. If you're using vero or perf, you might want to run a hobby knife between your traces/leads to make sure there are no solder bridges and get some of the flux off.

[alphadog808]

I only ground the input jack via wire and let the output jack get grounded through contact with the enclosure. I've never had any reliability issues because of this, and one less wire keeps the insides that much tidier. No matter how loose a jack is, it always seems to be making contact with the enclosure somewhere. I'm much more concerned about the tip part of the jack grounding out on the enclosure or on a pot case.

I'm not sure why all your pedals whine. When I started out, I ran a ground wire to both jacks and none of my early build had that issue. If you're not already doing so, it's a good idea to run a jumper from the effect input lug of the 3PDT to a lug that is grounded when the effect is bypassed. Sometimes not grounding the input can cause oscillation that bleeds into your dry signal when the effect is off. If you're using vero or perf, you might want to run a hobby knife between your traces/leads to make sure there are no solder bridges and get some of the flux off.

I'm actually using the 2pdt wiring as seen above, so my input should be grounded when it's off.  I actually run a hacksaw between the traces, it helps when you accidentally get a good sized glob on there...  Yah, I'm not sure why all my pedals exhibit this behavior.  I've used 9v batteries to test to make sure it's not my power supply either, so maybe it's just the room that I'm in(unlikely).  I'm thinking I'm doing something or not doing something that makes this happen.

What really blows my mind is the pedals will whine without something plugged in as well.  I've been able to get around it by making a pulldown resistor on the board(from 2.2k to 100k), but it would be nice to have a normal build, ya know?

[R.G.]

I only ground the input jack via wire and let the output jack get grounded through contact with the enclosure. I've never had any reliability issues because of this, and one less wire keeps the insides that much tidier. No matter how loose a jack is, it always seems to be making contact with the enclosure somewhere.

What happens when the pedal is some years old and the metal oxidizes?

I tend to err on the side of works-semi-forever, or at least try to.

The real story is that the enclosure should be connected to signal ground by exactly one wire, not two or more. This can be the bushing of one jack, but should not be two jacks. In a perfect world, only one jack would have a non-isolated bushing, and the rest would be isolated. However, pedals are so small and so low-power that pedal builders get away with things that would be disaster in bigger and more complex systems.

So - grounding one jack to the enclosure and the others from the enclosure works mostly. Loose nuts on the bushings can lead to scratchy intermittents as the pedals age. Paint and the enclosure metal, painting, and the lack thereof can make differences as well. None of this matters a whole lot if the pedal is new, or if you remember it years from now when you get into funny ground problems and have to clean things up.

[LucifersTrip]

Currently I tap the ground wire from the 9v connector and feed it to a small piece of vero that has a bunch of wires connected to it; essentially giving me multiple ground wires that I can run to the jacks, lugs, etc.  I think this ok, but I wasn't sure. 

I always thought that the left method was preferred, but I don't know the terminology or the technical benefits

[thelonious]

I always thought that the left method was preferred, but I don't know the terminology or the technical benefits

At least in amp world, the left method is called buss ground and the right is called star ground. Each has its (passionate) adherents. With buss ground, it's more important to place current-heavy things (like main filter cap) toward 'C' and sensitive things that don't involve much current (like signal grounds) toward 'A'. But I pretty much learned everything I know about that from reading amp dudes like Merlin and Randall Aiken, so in pedal world there might be other schools of thought.

Star grounding (right side) has worked great for me in both pedals and amps, but it does take more wire. Plus, it's one thing to star ground a point-to-point or turretboard amp, and quite another to create a PCB layout that uses star ground. 

[alphadog808]

Can someone clear up this grounding question for me?

 So I'm working on a pinnacle and in my attempts to stop the squeal when the boost is on, I've been doing some research and reading to see how people got around their problems.  Unfortunately, it seemed most people ended up living with it.

That being said, I did run across a poster on another forum who was mentioning that the pinnacle vero from here actually doesn't need to have vol1, contour3, and Gain1 on board.  He said I should be able to simply ground those lugs to the casing of the pot(assuming the pot is grounded).

I do see that those 3 lugs DO go to ground, so it makes sense to me, I think...

If that solution will work(even if doesn't stop the squeal), why does the vero not just have the user simply send those lugs to ground?  I'd think it'd be less work and less wires, and hopefully less noise.  

Just wondering if this might be a nice shortcut in wiring up veros...

[mremic01]

The layout is just how the guy who created it wanted to wire it. If you want to connect those lugs to ground somewhere else, it should be ok. If I can get a neater wire run by deviating from a layout in an instance like that, I usually go for it. If your enclosure is metal, and the pot casings have good contact with it, you could easily ground the lugs on the casing. It's technically less reliable, as the casings themselves are not soldered to something that's grounded and rely on physical contact, but in practice I don't think I've ever had a pot not make a solidly reliable connection to ground. This is how I wire my guitars. All the pot casing are grounded by contact with the shielding that lines the control cavity, then I run a clipped component lead from the lug to the back of the pot. I don't like to bend the lug to touch the casing like I see manufacturers do. 

[thelonious]

Or you can connect Vol1, Contour3, and Gain1 lugs to each other with short wires and then just run one wire to the board. I think that would be easier and more reliable than grounding to pot cases... but then I find it a big pain to get the back of the pot hot enough to get a reliable solder joint on it. Cold joints happen all the time on those.

[alphadog808]

Thanks guys, good to know that at least electrically I'm not doing something wrong.  As I just started doing this, I was trying to follow the instructions to a, "T".   It's actually really cool to see that these setups allow you to be creative to get cleaner wiring, etc. 

Note, I have the vol pot going to a ground wire and the rest of pots connected to the vol pot.  DMM shows good connection and after sanding the back of the pot, that solder just gels on that casing! 

[mremic01]

When I solder to the pot casing, I sand it and then clean it off with acetone. I use a binder clip to hold the component lead down flat on the casing when I solder. Once the joint is cool, it's usually much neater looking than the typical solder blobs you see inside most control cavities.

[thelonious]

When I solder to the pot casing, I sand it and then clean it off with acetone. I use a binder clip to hold the component lead down flat on the casing when I solder. Once the joint is cool, it's usually much neater looking than the typical solder blobs you see inside most control cavities.

I am going to try this for sure! Good advice.

[tubegeek]

Flux.