Bass Has Weird Noise Issue

[Old Garage-Bander]

It is my understanding with proper shielding, this interference/noise shouldn’t be audible. I suppose some people with just live with it, but it bothers me that my two cheap Ibanez basses are dead silent and my high-end warrior bass has an annoying (but subtle) noise if it isn’t being grounded by my hands to the strings. Just seems wrong to me. Lol

There is no way to fully shield the electronics in a bass. There are always going to be "leaks" somewhere. Some of those leaks can even act as an antenna unto itself. (Slot antenna).

Different electronics is also going to react to interference in different ways. Your Warrior likely has different electronics than what was designed for your two Ibanez basses. It's not about good or bad design, but about different design.

Radio frequency energy and interfering signals can be a PhD level of study where someone can devote their whole life to the subject and still not figure it all out. It also is not very intuitive as to what's going on. You can't just look at it and see a problem that jives with our normal everyday experiences.

Unless you want to do a noise audit of your space, and power down any offending equipment (if possible) while playing, you might just have to live with little bit of noise. Most of us do to a certain extent. And the more electronic stuff that pervades our lives, the more we will be affected by this.

 

[Lostgallifreyan]

There is no path to ground when I am standing on a rubber mat, yet the noise disappears when I touch anything on the bass that is grounded. Clearly I am not providing a path to ground, but the bass is.

A rubber mat may couple a noise signal by acting like the dielectric of a capacitor. Two feet (human, not units of distance) separated from the ground by an insulator can amount to a fairly large capacitance, and combined with a high resistance if a ground isn't right, that capacitance may have a strong effect. DC will be blocked, but AC noise won't be.

The real problem is in assuming the bass is grounded. ANY of these effects are usually enough to prove it's not because the purpose of a good ground is to make them insignificant.

Given that a bass or guitar usually feeds a preamp input that has a very high resistance, because it expects that the volume control in the guitar itself has a high resistance, a proper signal can get through even if the ground is poor, so even if the guitar plays ok it can still mean the ground isn't as good as it should be. In practise it rarely is. It may just be that in this case something is unusually poorly connected, but I can't see it in front of me so I can't track it down.

I have solved this condition in one bass though, it turned out to be a very poorly fitting bridge on a bass I bought, it was resting on the insulation of a ground wire, hence making poor contact with the metal strands...

 

[uOpt]

Yeah, nothing here has anything to do with either:
- the floor you are standing on (that's not the "ground" we are talking about here)
- the ground/earth wire in a 3-prong AC power connection. The shielding and everything else works the same way even when you go through a 2-prong adapter

 

[BlueTalon]

The whole point of shielding (grounded shielding) is to intercept/shunt RF/EM energy so that it doesn't adversely affect the signal. Since it's impossible to completely surround the pickup(s) with shielding, it's impossible to create the Faraday cage that would fully protect the signal chain. Nevertheless, we can still do a very effective job with it. But it all has to be connected, and that fully connected shielding has to be grounded to the signal ground. A shielded but ungrounded pickup route will act like a radar dish, exactly the opposite of what we want. A shielded and grounded pickup route will act more like a baseball backstop. (Not a perfect analogy, but close enough for the purpose.)

On a properly shielded/grounded bass, assuming there are no other faults in the circuit, touching the strings should have no effect. There should be no pops, and no difference in noise. But it's not bulletproof. Sometimes the environment is such that you just can't eliminate the noise -- but that would hold true for every bass. For example, if I play while sitting next to my computer, my bass is going to pick up noise from that no matter how well it's been shielded. So to become silent, I either have to move my computer or move myself.

Hum canceling pickups are the other part of the equation, but that's a personal choice thing. Some people are willing to put up with the possibility of extra noise for perceived benefit regarding tone. I am not among them.

 

[Turnaround]

A rubber mat may couple a noise signal by acting like the dielectric of a capacitor. Two feet (human, not units of distance) separated from the ground by an insulator can amount to a fairly large capacitance, and combined with a high resistance if a ground isn't right, that capacitance may have a strong effect. DC will be blocked, but AC noise won't be.

The real problem is in assuming the bass is grounded. ANY of these effects are usually enough to prove it's not because the purpose of a good ground is to make them insignificant.

Given that a bass or guitar usually feeds a preamp input that has a very high resistance, because it expects that the volume control in the guitar itself has a high resistance, a proper signal can get through even if the ground is poor, so even if the guitar plays ok it can still mean the ground isn't as good as it should be. In practise it rarely is. It may just be that in this case something is unusually poorly connected, but I can't see it in front of me so I can't track it down.

I have solved this condition in one bass though, it turned out to be a very poorly fitting bridge on a bass I bought, it was resting on the insulation of a ground wire, hence making poor contact with the metal strands...

The point is that you are not grounding the bass when touching it. It is already grounded - if it wasn't connected to the ground of the amp it wouldn't work, there would be no circuit. When you touch the strings (assuming the ground wire to the bridge is good) you are connecting yourself to the same ground plane as the amp and the bass i.e. you are grounding you, not grounding the bass. You can accomplish the same thing by touching a ground point on the amp without touching the strings - the noise will be dissipated. The point is that you all share the same ground plane - the amp, the bass, the player.

 

[Lostgallifreyan]

The point is that you are not grounding the bass when touching it. It is already grounded - if it wasn't connected to the ground of the amp it wouldn't work, there would be no circuit. When you touch the strings (assuming the ground wire to the bridge is good) you are connecting yourself to the same ground plane as the amp and the bass i.e. you are grounding you, not grounding the bass. You can accomplish the same thing by touching a ground point on the amp without touching the strings - the noise will be dissipated. The point is that you all share the same ground plane - the amp, the bass, the player.

Ideally, yes, but it's rarely ideal. I don't mean blurring the issue here, I literally mean that grounds are relative (hence the relation to the RF 'counterpoise'). Imagine that Monty Python thing, where the middle class guy can look up or down the the guy on each side of him.. As to which way the mid 'ground' might be 'looking', there is still some AC potential difference. If it were not so, there'd be no current, and no noise would result.

One big clue that some capacitative coupling exists in any situation is when that noise sounds filtered, buzzy, usually lacking in bass end. And if that exists, then the most certain deduction is that the resistance somewhere is higher than it should be, and making a high-pass filter with that capacitance. If the relative grounds were all strongly tied, the noise would be reduced to the point where only localised and strongly directional noise is likely to dominate. (As Bluetalon says, can't shield everything perfectly..)

Also, consider the amp input resistance, very high, because a guitar might have a high output resistance (in the case of passive volume pots at 250K or more). What that means is the guitar can still work even if some ground in its main signal path is several tens of kilohms. That might also be more than enough for a potential difference in ground capable of driving noise. I suspect as little as 10 ohms difference might be enough, but it would depend on ambient strength. A continuity tester might think 10 ohms is 'continuity'. I don't know what people are using to test, but it's worth bearing this in mind..

 

[JBoogy]

A couple of videos I took to share with the Repair Shop. The first one is the Warrior bass making the noise. The second is an Ibanez bass not making the noise. Same cord, amp, room, power, everything. The bass is the only difference.

[Invalid or Expired Link Removed]
[Invalid or Expired Link Removed]

 

[Turnaround]

I don't mean blurring the issue here....

But you are blurring the issue. Practically speaking, when your body is in close proximity to the bass the noise is abated when your body is grounded to the same ground plane as the bass/amp. If your strings are grounded, you become grounded when you touch the strings. Or you can touch a ground point on the amp - same effect. You said it yourself .. "If the relative grounds were all strongly tied, the noise would be reduced to the point where only localised and strongly directional noise is likely to dominate."

 

[JBoogy]

I also did another round of trying the bass with my amp in different rooms and different cables, even tried at a friend's house. Same issue. So, I am definitely calling the repair shop to take it back up there. I took videos but I plan on taking my amp as well to "recreate" my rig at the shop and show them.

 

[Lostgallifreyan]

I also did another round of trying the bass with my amp in different rooms and different cables, even tried at a friend's house. Same issue. So, I am definitely calling the repair shop to take it back up there. I took videos but I plan on taking my amp as well to "recreate" my rig at the shop and show them.

Worth the extra effort, so go for it. The fact that it was repeatable and consistent gives some chance the context can be replicated there. Just be prepared for any surprises.

If they are conscientious I doubt they'll mind. They'll probably like the effort to find out for sure. Better basis for trust in the end.

 

[Lostgallifreyan]

But you are blurring the issue. Practically speaking, when your body is in close proximity to the bass the noise is abated when your body is grounded to the same ground plane as the bass/amp. If your strings are grounded, you become grounded when you touch the strings. Or you can touch a ground point on the amp - same effect. You said it yourself .. "If the relative grounds were all strongly tied, the noise would be reduced to the point where only localised and strongly directional noise is likely to dominate."

I still don't buy it, but on the other hand I'm not saying you can't be right, and I didn't mind taking time to try to replicate this.

Two basses, Westone Thunder 1-A (Fender P-bass emulation with active electronics) and a Status Graphite, also active, pickup types unknown to me). Strings confirmed as grounded, resistance between them and audio jack ground being less than 0.5 ohm.

Two noise sources, Mackie HR-824 (mostly magnetic) and Casio projector on standby (mostly electrostatic), at very close range, about one foot, with pickups, source, and me, at approximately the points on an equilateral triangle. Each bass held so I could easily contact the strings while otherwise minimising movement with the main grip isolating me from the metal, touching only the wood.

Each time I got noise but touching the stings never changed anything. Grounding my body never changed anything. I could not replicate the problem, and I stand by my prediction that I could not do so without deliberately compromising the grounding somewhere inside the bass or the line connection to the preamp.

I won't experiment to that point. I like my basses as they are and want to keep them that way..

 

[Turnaround]

It's still a shielding problem. When you touch the strings or the amp chassis the noise is getting drained away from the bass.
Some basses are easier to shield than others. And you can't om

I still don't buy it, but on the other hand I'm not saying you can't be right, and I didn't mind taking time to try to replicate this.

Two basses, Westone Thunder 1-A (Fender P-bass emulation with active electronics) and a Status Graphite, also active, pickup types unknown to me). Strings confirmed as grounded, resistance between them and audio jack ground being less than 0.5 ohm.

Two noise sources, Mackie HR-824 (mostly magnetic) and Casio projector on standby (mostly electrostatic), at very close range, about one foot, with pickups, source, and me, at approximately the points on an equilateral triangle. Each bass held so I could easily contact the strings while otherwise minimising movement with the main grip isolating me from the metal, touching only the wood.

Each time I got noise but touching the stings never changed anything. Grounding my body never changed anything. I could not replicate the problem, and I stand by my prediction that I could not do so without deliberately compromising the grounding somewhere inside the bass or the line connection to the preamp.

I won't experiment to that point. I like my basses as they are and want to keep them that way..

Well of course - touching the strings doesn't take away all the noise, only that relating to your body. In your test any noise you got was not coming from your body - it was coming directly from the Mackie and/or the Casio (or possibly other sources nearby. THere's going to be some EMF entering the pickups directly - they're not shielded. And if you have hot pickups, as I believe the Warrior in question has, the problem can be more pronounced than with regularly wound pickups.

 

[uOpt]

A couple of videos I took to share with the Repair Shop. The first one is the Warrior bass making the noise. The second is an Ibanez bass not making the noise. Same cord, amp, room, power, everything. The bass is the only difference.

[Invalid or Expired Link Removed]
[Invalid or Expired Link Removed]

To be honest, the only unusual thing here is how well the Ibanez seems to be shielded from the factory. That buzz when letting go of the strings is the normal case.

What is odd, though, is that the noise didn't improve when your tech added some shielding. It would be good to know what exactly that was (photo?).

 

[JBoogy]

I realized I hadn't updated this thread, so I wanted to jump back in and update everyone in case anyone was following it.

I took it back to the shop and they took another look at it. Another technician noticed almost immediately that there was a ground wire underneath the pots that was not connected. They re-connected it and presto, no more issues at all. Sounds great. And I am not crazy, they disconnected that wire. I thought when I first bought the bass it was fine, and it turns out they accidentally disconnected that wire dring their original electronics check and didn't reconnect. And then missed it again. So they bass was never at fault, just my local guys made a mistake and didn't catch it at first. Luckily I was persistent and they finally caught it! It now has the brand new preamp which I liked better anyways since it has a push/pull active/passive control on the volume knob and the original preamp didn't. So that is the conclusion.

 

[Old Garage-Bander]

According to the repair shop, they checked all the grounding and shielding and could not find any issues, but for good measure added extra shielding anyways in the electronics cavity. I have no reason to not trust them as they have done lots of work for me and my friends over the years and it's always been top-notch. They seemed perplexed at first too, spending weeks with it. Then after the new preamp was installed they said it was good now. I specifically asked about this exact issue when I picked it up and the technician said he played it for over 20 minutes straight plugged into several different amps and never had a single issue. So I really left assured it was fine now and was greatly surprised and disappointed to find it still did it. I don't know how to take a bass apart and check grounds and all so I mean I assume it is based on the technician's statements, but I am confused why they had no issue with it and I do.

Location, location, location.
You can play on all the amps in all the gin joints in all the world and not duplicate whatever is happening at the location where the noise/hum/whatever occurs.
You are using a different electrical outlet, in a location that had as different noise environment from that of your repair tech's shop.
You should verify a properly connected/operating wall outlet. If you have something wrong with your outlet or otherwise with the electrical service an electrician can bring things up to code. That however, is no guarantee that it will fix the problem you are experiencing. If you have other sources of noise in your location contributing to the problem, that requires a very systematic set of troubleshooting procedures. In some cases it requires having special types of test equipment. There are few, if any, people I know of who specialize in solving these types of problems as a career. And if you were to find someone to do this on a professional basis the cost would be prohibitive.

One thing you can try is to shut off, AND UNPLUG FROM THE WALL, everything in your location, except for your amp, and see if the noise goes away or is reduced. If not, there isn't much else you can do. If it improves, then you will need to power down each thing in your location, one at a time to see if you can isolate what may be mulltiple offending devices. But be sure to only unplug JUST ONE and see what happens, then plug it back in before going to the next. Once you've identified the individual noise souces, unplug them all. (Just turning off a power switch does not mean the noise source is eliminated. You have to unplug from the wall.
Now you need to decide what you can live with being off while playing and what you can't. And is whatever noise you are experirncing worth putting up with not having the other device operating.

 

[BlueTalon]

...

Pssst. Read the post directly above yours.

 

[Old Garage-Bander]

Pssst. Read the post directly above yours.

Thanks. Yeah I missed that.

 

[Old Garage-Bander]

I realized I hadn't updated this thread, so I wanted to jump back in and update everyone in case anyone was following it.

I took it back to the shop and they took another look at it. Another technician noticed almost immediately that there was a ground wire underneath the pots that was not connected. They re-connected it and presto, no more issues at all. Sounds great. And I am not crazy, they disconnected that wire. I thought when I first bought the bass it was fine, and it turns out they accidentally disconnected that wire dring their original electronics check and didn't reconnect. And then missed it again. So they bass was never at fault, just my local guys made a mistake and didn't catch it at first. Luckily I was persistent and they finally caught it! It now has the brand new preamp which I liked better anyways since it has a push/pull active/passive control on the volume knob and the original preamp didn't. So that is the conclusion.

Excellent! Glad to hear the news.
Call backs happen. Good techs will do what's needed to resolve them.
Sounds like your guys are keepers.