Got damn buzz! Please help!!

[DWBass]

Electrical wiring can come into play as well. Many times an outlet is connected to several other outlets/sources and not stand alone circuits. Something in the chain is causing the noise. Also, if you are in the studio, the monitor can be a huge factor. I've yet to hear any bass with single coil pickups be totally silent. Even Fender Noiseless pickups are not totally silent. I know, I've had a set at one time. Actually horrible pickups, IMHO.

[dmusic148]

Originally Posted by VBassRookie

You very much can have a ground loop. Here is a link diagramming the issue. With an explanation of the ground loop issue:
http://www.talkbass.com/wiki/index.p...Signature_Bass
y

If you understood what a ground loop actually is, you would understand that this is nonsense.

[Winston Wolf]

Are the pickups in your 97 MIM Jazz Bass the same size, or is the bridge pickup larger than the neck pickup? Apparently Fender used neck pickups in both the neck and bridge positions in some of the MIM Jazz Basses from that era. They are wound the same so they are not noise canceling when both pickups are on (or when used solo). Just something else to consider when dealing with noise on this era MIM Jazz Basses and buying replacement pickups for them.

[warnergt]

Originally Posted by dmusic148

If you understood what a ground loop actually is, you would understand that this is nonsense.

If you understood what a ground loop actually is, you would
explain why you believe he is wrong instead of posting this
unhelpful, condescending comment.

[SGD Lutherie]

Originally Posted by VBassRookie

You very much can have a ground loop. Here is a link diagramming the issue. With an explanation of the ground loop issue:
http://www.talkbass.com/wiki/index.p...Signature_Bass

No, you can't. A ground loop is when you have two points in the circuit with a different ground potential, and they are connected together. That causes current to flow in the shared grounds, which causes hum. This is common in something like a tube amp where you have high voltages and different impedances. Or the common cause of a ground loop is two different AC powered devices connected together.

In a bass you have one ground reference, at the output jack. Nothing in the bass can be at a different potential. Even taking wire resistance into consideration, they are all too short to matter. Ad parallel ground paths will reduce the resistance further.

the link you referenced is nonsense. Notice that in that bass all the pots are sitting on aluminum foil. So removing the connecting ground wires does nothing.

To understand what star grounding is, and when you need to use it, read this article:

http://www.geofex.com/Article_Folder...nd/stargnd.htm

"The point of star grounding is to keep signal circuits with NO common mode noise rejection (that is, all the normally used tube gain stages) from picking up current-induced noise from other currents running through a shared ground. Obviously, the most critical stage is an input stage, and the closer you go to the output stage, the bigger the signal level and the less the milli- and micro-volt signals in the shared ground will be."

In a bass there are no currents running through shared grounds. If you do some searches on TalkBass and other places, people who do the GuitarNuts star grounding thing often have more noise after the mod than they started with.

[-=DanAtkinson=-]

Thanks to SGD for saying what I was too lazy to type.

[SGD Lutherie]

Originally Posted by -=DanAtkinson=-

Thanks to SGD for saying what I was too lazy to type.

I type that explanation so many times, I should save that as a text clipping!

[warnergt]

Originally Posted by SGD Lutherie

In a bass you have one ground reference, at the output jack. Nothing in the bass can be at a different potential.

Based on this statement, I can connect the ground wire from
my pickups to my grounded bridge because, as you claim,
all grounds are the same within a bass.

I think most of us would agree that connecting the pickup
through the bridge is a bad idea.

Originally Posted by SGD Lutherie

To understand what star grounding is, and when you need to use it, read this article:

http://www.geofex.com/Article_Folder...nd/stargnd.htm

"The point of star grounding is to keep signal circuits with NO common mode noise rejection (that is, all the normally used tube gain stages) from picking up current-induced noise from other currents running through a shared ground. Obviously, the most critical stage is an input stage, and the closer you go to the output stage, the bigger the signal level and the less the milli- and micro-volt signals in the shared ground will be."

That is correct.

Originally Posted by SGD Lutherie

In a bass there are no currents running through shared grounds..

This is incorrect. There are currents running everywhere
inside everything. Electromagnetic and magnetic waves are
inducing currents in anything and everything that will
conduct current. The point of proper grounding, which
includes star grounding, is to reduce or eliminate the
contributions of these unwanted signals to your desired signal.

No two different ground points are at the same potential ever.
This is a reality that engineers must understand for low noise
design. And this is why low noise design strives for single-
point grounds (as in a star ground topology).

It is possible that your bass doesn't use a star ground
topology and it sounds fine. That can happen. Your noise
levels may be low enough that it doesn't matter that much
but the reality is that single point grounds reduce undesirable
signals.

Here is an article from the IEEE that covers it pretty well:
Grounding Demystified

[SGD Lutherie]

Originally Posted by warnergt

Based on this statement, I can connect the ground wire from
my pickups to my grounded bridge because, as you claim,
all grounds are the same within a bass.

I think most of us would agree that connecting the pickup
through the bridge is a bad idea.

The bridge is not ground. The bridge is connected to ground.

Why would you think the bridge is ground? The bridge and strings are grounded as to ground you. That cuts down on noise that your body picks up.

On an electric bass ground is at the output jack. Ground loops need to have two different grounds, and your bass only has one.

I understand grounds. I have a background in electronics and worked for a large defense contractor back in the 70s. The stuff in the article you posted does not pertain to an electric bass. It may pertain to your amp, but think about this; your amp most likely does NOT use star grounding. Even if it's a tube amp. Are you hearing any hum? That's because there's more than one way to fix that problem. Also note that no guitar manufacturer uses start grounding. That's because it's not needed.

Fender's problem is that they use conductive paint that is often not grounded, and they often have other shields that are not grounded. It's just cheap and shoddy work. None of my basses hum or buzz, and none use star grounding. They aren't even shielded. Only the pickups are.

Also, the noise people keep talking about that this is supposed to solve is that high pitched buzz that is the results of electrical field noise, not ground loops. Ground loop noise is generally 60Hz (in the US) hum from power mains. That's the stuff that hum canceling pickups get rid of.

Yes, there are currents flowing in all conductors on your bass, including eddy currents caused by the magnets in the pickups (providing the pickups have metal parts). But none of that will cause ground loop noise in your bass. And it certainly wont cause the high pitched electrical field buzz. That's an external noise source that is being picked up by the metal parts on the bass.

[warnergt]

Originally Posted by -=DanAtkinson=-

Ground loops are a common myth in guitar wiring, or at least they are in internal wiring of the guitar. They can occur between amps and pedals, but not inside the guitar, no matter how many redundant ground paths you have.

Read here for more info, and for an explanation on the pointlessness of star grounding:

http://searcystringworks.blogspot.co...ding-myth.html

I read that article. I find it contradictory.

He says, "Because every component in a guitar or bass is grounded at the output jack it was already "Star Grounded" when you bought it."

And he goes on to say, "[Star grounding is] a total waste of time and should be avoided. Am I being unclear?"

If it can't be avoided, how can he instruct us avoid it?
Also, he has given no reason to support his demand to
avoid it. Why should we avoid it? If it makes no difference,
as he claims, there is no reason to avoid it. If some people
say it works and he says it does nothing, I see no reason not
to employ it. Why take chances?

He also seems to believe that all grounds in a bass are
equal. This is simply not true and goes back to the example
that you don't want to ground your pickup at the bridge.

One other point. He says, "Ground loops are real and they can be noisy little buggers that occur when you can trace a loop in the ground connections between separate pieces of AC powered equipment in your signal chain."

DC powered car stereos have ground loop problems all the
time. Perhaps his weren't the best choice of words and he
merely meant separate pieces of "grounded" equipment. My
point is that AC power is not a necessary condition for ground loops.

[warnergt]

Originally Posted by SGD Lutherie

The bridge is not ground. The bridge is connected to ground.

So, now you admit that all grounds are not equal.

Originally Posted by SGD Lutherie

The bridge is not ground. The bridge is connected to ground.

Exactly. The same thing can be said for every other
grounded point in your bass that is not at your single point
ground.

Originally Posted by SGD Lutherie

Why would you think the bridge is ground?

I didn't say it; you did. You said, "Nothing in the bass can be at a different potential."

Originally Posted by SGD Lutherie

On an electric bass ground is at the output jack. Ground loops need to have two different grounds, and your bass only has one.

You're contradicting yourself. A second ago, you told me that
the grounded bridge is not ground. Now, you tell me there
is only one ground.

If there is only one ground, shouldn't all ground connections
go directly to it?

Originally Posted by SGD Lutherie

I understand grounds. I have a background in electronics and worked for a large defense contractor back in the 70s.

I've been an electrical engineer for almost 30 years and have
been electronics since the mid-70's including working for
a large defense contractor. Does it really matter?

I'm more than willing to compare credentials and background
but this proves nothing and gets us nowhere.

Originally Posted by SGD Lutherie

The stuff in the article you posted does not pertain to an electric bass.

Absolutely false.

Originally Posted by SGD Lutherie

...your amp most likely does NOT use star grounding.

They may not call it "star grounding" but a good amp designed
for low noise will employ single point grounding techniques
or differential signals to avoid ground loop problems.

Originally Posted by SGD Lutherie

Also, the noise people keep talking about that this is supposed to solve is that high pitched buzz that is the results of electrical field noise, not ground loops. Ground loop noise is generally 60Hz (in the US) hum from power mains. That's the stuff that hum canceling pickups get rid of.

Avoiding ground loops can reduce or eliminate the contribution
of this noise.

Originally Posted by SGD Lutherie

Yes, there are currents flowing in all conductors on your bass, including eddy currents caused by the magnets in the pickups (providing the pickups have metal parts). But none of that will cause ground loop noise in your bass. And it certainly wont cause the high pitched electrical field buzz. That's an external noise source that is being picked up by the metal parts on the bass.

Magnets don't cause eddy currents; alternating magnetic
fields cause eddy currents.

Proper circuit design can allow induced noise to cancel out.
Ground loops impede this cancelling effect.

[SGD Lutherie]

Originally Posted by warnergt

So, now you admit that all grounds are not equal.

No, I said nothing of the kind. I said the strings are not ground. You didn't explain why you think it is.

The strings connect to ground. If you connect to the same ground wire that leads to the bridge, the other end of which is connected to ground, then that's a perfectly good ground.

I don't know how your instruments are wired, but my string ground is connected to the back of a pot. That same pot has a wire going to the other pots, and the output jack. All these points are at the same ground potential. That ground is established at the first ground outside of your bass, which is probably the amp. If you have a second ground in that path, such as from an AC powered pedal, or DI, you might very well get a ground loop going, and have to lift that ground. That's why they make ground lift switches on DIs.

That should be a clue to you right there; ground loop = two grounded systems connected together. Each one has its own ground connection, very often to a different ground circuit.

Your bass has a single ground point at the output jack. Nothing is grounded until you plug in your bass to the grounded amp.

Exactly. The same thing can be said for every other
grounded point in your bass that is not at your single point
ground.

No. Every part of the bass that is connected to ground, is connected to ground.

Please demonstrate how the back of one pot is not at the same ground potential as another. Do you really think that a inch or two or wire will change that? It wont. You also can't measure any resistance in a short length of wire.

I didn't say it; you did. You said, "Nothing in the bass can be at a different potential."

And it's not. Prove it is.

You're contradicting yourself.

I'm not. You either don't understand what I'm saying, or you just want to twist it around to make me sound like I am.

You started this post with a really dumb remark. You stated that the bridge/strings were ground. I'm sorry, but that kind of negates the rest of your argument.

If you want to demonstrate how two points several inches away from each other in the bass are at a different ground potential, then be my guest. Show us some real measurements, not conjecture.

Then give us a demonstration on how you can produce a ground loop. And I don't mean electrical field hash, I mean a real ground loop. One that produces a low frequency hum. You should also be able to measure that current flowing in the ground wire.

[wvbass]

This is the most enjoyable thread I have seen in a while. On one side, we have someone who is completely wrong, and being very stubborn about it. On the other side, we have someone calmly and accurately explaining the same thing over and over, and it landing on deaf ears.

Can you tell which is which? This thread reminds me of why Bill quit posting here.

[WoodyG3]

Originally Posted by wvbass

Can you tell which is which? This thread reminds me of why Bill quit posting here.

I don't know who is who, but it is entertaining.

[warnergt]

Originally Posted by SGD Lutherie

No, I said nothing of the kind. I said the strings are not ground. You didn't explain why you think it is.

How did this conversation switch to strings? You said, "In a
bass you have one ground reference, at the output jack.
Nothing in the bass can be at a different potential."
Do you deny saying this? Anybody can go back and see it.

So, if a grounded bridge is at ground potential, which you
insist that it is, I can tie my pickup to it as, if you are right,
it will be as good as any ground in the bass.

Originally Posted by SGD Lutherie

That should be a clue to you right there; ground loop = two grounded systems connected together.

This brings us to the other problem with the arguments
against star grounding. Star (single-point) grounding is not
only to fight common-mode currents; it also establishes a
good ground for your signals. I think most of us would agree
that a grounded bridge would not be an appropriate ground
for a pickup or other bass components (although you keep
giving mixed answers as to whether it is ground or not).

Originally Posted by SGD Lutherie

Your bass has a single ground point at the output jack. Nothing is grounded until you plug in your bass to the grounded amp.

You're getting off on a tangent here (and I would say grasping
for straws to get out of this argument). Every bass has a
reference point for all of the signals within. This is the
definition of a ground. See Wikipedia if you don't believe me.

When you plug in your bass, you are connecting your bass
ground to your amp ground.

Originally Posted by SGD Lutherie

Please demonstrate how the back of one pot is not at the same ground potential as another. Do you really think that a inch or two or wire will change that? It wont. You also can't measure any resistance in a short length of wire.

And it's not. Prove it is.

Unless your pots are perfect conductors connected with a
perfect conductor, there will be a voltage difference between
the two. As I already pointed out, there are induced noise
currents flowing everywhere within everything. Noisy guitars
(I'm sure you'll agree that they exist) are evidence of these
noise currents. Ohm's law (E = I * R) tells me that, if I have
current (I) and a non-zero resistance (R), I will have a
voltage (E). The conclusion is inescapable.

Furthermore, why are we restricting this debate to an inch or
two of wire between two pots? Let's go back to the more
intuitively obvious bridge connection. If you insist that there
is no potential difference, we should be able to connect the
pickup to the bridge. Is there anybody here who believes
that would be acceptable?

Originally Posted by SGD Lutherie

You started this post with a really dumb remark. You stated that the bridge/strings were ground. I'm sorry, but that kind of negates the rest of your argument.

I said no such thing. Please go back and reread. You are the
one who is insisting that there is no differences between
grounds in a bass. I pointed out that, if this were true, a
grounded bridge could serve as an adequate ground for any
component within the bass. I, of course, do not subscribe to
that notion.

Originally Posted by SGD Lutherie

If you want to demonstrate how two points several inches away from each other in the bass are at a different ground potential, then be my guest. Show us some real measurements, not conjecture.

Then give us a demonstration on how you can produce a ground loop. And I don't mean electrical field hash, I mean a real ground loop. One that produces a low frequency hum. You should also be able to measure that current flowing in the ground wire.

I already explained that noisy guitars are proof that stray
signals exist within guitars. Do you deny that noisy guitars
exist?

Also, the pickup to bridge connection example is not an
example of a ground loop; it is an example to demonstrate
a benefit of star grounding implementation -- one that
overcomes the essential fact that no two grounding points
are the same potential. The only way to overcome this
reality is to choose a single ground point.

[-=DanAtkinson=-]

Originally Posted by wvbass

This is the most enjoyable thread I have seen in a while. On one side, we have someone who is completely wrong, and being very stubborn about it. On the other side, we have someone calmly and accurately explaining the same thing over and over, and it landing on deaf ears.

Can you tell which is which? This thread reminds me of why Bill quit posting here.

It reminds me of why I quit posting here as well.

[SGD Lutherie]

Originally Posted by warnergt

How did this conversation switch to strings?

Seriously? Go back and take you time and READ what you wrote before. I'll help you.

You said:


I replied:



So YOU brought up strings and the bridge. But yes, if you ran a ground wire under the bridge, and the bridge is grounded, you can ground your pickups to it.

Why couldn't you? Feel free to try it. But no one said to do that. The bridge is not what is used for connecting wires. The pot cans works well.

I will not engage you any further because you don't have a clue what you are talking about, and you have not answered the following questions:

1. Most amps do not use star grounding. Why don't they hum?

2. Printed circuit boards don't use star grounding, and many have multiple ground paths. Why don't they hum?

3. Why don't all guitar manufacturers use star grounding

It's not needed, that's why.

This one was good:

Unless your pots are perfect conductors connected with a
perfect conductor, there will be a voltage difference between
the two.

This is what happens when someone is quoting first year electronics stuff. In the real world it doesn't work like that. if it did, the pioneers of fed would have changed the way they wire stuff.

You make a solder connection. If it's a good connection, it's a good connection. Why do you think your star ground connection will be any better? It's the same solder connection.

But go ahead and demonstrate a ground loop in your bass. otherwise it's just talk.

And look at the way Fender does it. They mechanically attach the pots to a chrome plated control plate, and then don't even bother soldering ground wires. That's shoddy, but it has been working for the last 50 years. You certainly don't want to trust mechanical connections, or else we would be twisting wires together and not using solder. But it actually works most of the time. it's not that critical.

If you are building a point to point wired tube amp, use star grounding. Otherwise you don't need it.

Nice line breaks by the way.

[WoodyG3]

Is it me, or is someone being purposely obtuse?

The strings are in contact with the bridge. Get it?

Everyone is in agreement that for anything to be grounded it has to be in some way connected to the ground on the output jack. Get it?

I know nothing about ground loops and whether star grounding is a good or unnecessary thing, but someone's purposely missing the point of someone else's post, me thinks.

[warnergt]

Originally Posted by SGD Lutherie

Then give us a demonstration on how you can produce a ground loop. And I don't mean electrical field hash, I mean a real ground loop. One that produces a low frequency hum. You should also be able to measure that current flowing in the ground wire.

I thought about this challenge for a while and have decided
to take you up on it. By the way, ground loops can produce
more than just "low frequency hum." They are responsible
for all kinds of noise.

Some people claim that there can be no ground loops within a
passive guitar. I will show you right here, right now how that
claim is false.

First, let's look at a guitar employing a single-point (star) ground:



Note how the noise current is essentially shorted out by
employing the single point ground. It has no contribution to
our signal going to the amplifier. This is what we want.

Let's take a look at that guitar built by the guy who refuses
to use single-point (star) grounding:



Now, we have an interesting situation. The noise current (In)
is sharing a path (in red) with our signal. As this path has a
non-zero resistance (Rg), the noise current is creating a
noise voltage (Vg) along this path (Vg = In * Rg). This noise
voltage is in series with signal voltage (Vs). Thus, going to
our amplifier, we get signal plus noise (Vs + Vg).

By the way, suddenly we have a circuit that looks extremely
similar to the problematic circuit shown in that IEEE Ground Demystified
document that I recommended earlier (remember the one
you said "does not pertain to an electric bass"?). Let's take a
look at that.



Note that there is a noise voltage in series with the signal voltage.
This is the situation that the IEEE is telling us to avoid and
this is the situation that you get if you choose to ignore the
benefit of star-grounding.

By the way, I showed the shield and bridge acting as an antenna.
The reality is that every component in your guitar is acts as
an antenna in some way -- some obviously more than others.
I showed one noise source; there could be many. So, keeping
this in mind, there are two ways you can approach guitar building:

Guitar builder #1 says, "These noises are trivial. I know what
my customers will experience because I am psychic. I don't
need no stinkin' star grounds. Run the ground wires any old
way and be sure to avoid star grounds."

Guitar builder #2 says, "There are many noise sources. There
is no telling what environments my customers will be playing
in. I want to use best design practices such as single-point
grounds as recommended by the IEEE to minimize the effects
of these noise sources."

I know which builder I want building my guitar.

[-=DanAtkinson=-]