Got damn buzz! Please help!!

[SGD Lutherie]

Originally Posted by warnergt

The fact is that the star ground topology in a guitar reduces
susceptibility to noise.

Based on what evidence? You have offered no proof at all.

If you are going to make a statement and say it's a fact, show some scientific proof that star grounding reduces noise in guitars or basses.

Otherwise you are just talking. Now it's time to back it up. We will wait.

Also, shielding has nothing to do with star grounding.

(sorry had to come back just for this).

[warnergt]

Originally Posted by dmusic148

...noise will follow the path of least resistance, which is to ground. It all ends up at the third lug of your power cord, which is what the - terminal of your guitar cable is attached to. Ground. Down the drain it goes, unless something is faulty. It doesn't go round in circles. It goes to ground.

By the way, why must noise go to ground? Do you believe
that there is some reason that induced signals only go to
ground? If I connected a battery between my shield and
bridge, how much of that current would flow down my
guitar cable to ground?

Please enlighten us.
I can't wait to hear your answer.

[warnergt]

Originally Posted by SGD Lutherie

Based on what evidence? You have offered no proof at all.

I gave an example.
Google for "single point grounding."
Here, I'll do the work for you. Click below:
single point grounding

There are articles all over the Internet which unanimously
agree in the benefits of single point grounding for reducing noise.
Given this information, try to understand what the value of
single point grounding is.

Originally Posted by SGD Lutherie

Also, shielding has nothing to do with star grounding.

I never said it did. I brought that up as a counter-argument
to dmusic148's claim that there were no noise currents in
guitars. Shields block electromagnetic signals from inducing
noise currents. If noise currents didn't exist within guitars
(as dmusic148 claimed), shielding would be unnecessary.

[dmusic148]

Originally Posted by warnergt

By the way, why must noise go to ground? Do you believe
that there is some reason that induced signals only go to
ground? If I connected a battery between my shield and
bridge, how much of that current would flow down my
guitar cable to ground?

Please enlighten us.
I can't wait to hear your answer.

You know the answer-it's a short circuit. Current will flow in this circuit because there is a source with a clear +/-. No contradiction. Also no noise potential, as it's DC anyway.
Now, if I connected the battery + to the bridge, and battery - to my house AC ground, what would happen?
This is a much more realistic example.

[bumperbass]

If you think this article is correct and what it says really makes a difference, you don't understand. I'm sorry to say, warnergt, you're misled.

http://alexplorer.net/guitar/basics/grounding.html

It wouldn't matter if there was an extra 10 wires in there going to every single ground and back again. It wouldn't matter.

dmusic148, you will never win an argument with someone who is misled or doesn't understand. Give up like I am right NOW. See ya!

[SGD Lutherie]

Originally Posted by warnergt

I gave an example.
Google for "single point grounding."
Here, I'll do the work for you. Click below:
single point grounding

I'm not asking you to point to an unrelated article on the web. I'm asking you to prove that star grounding reduces noise in an electric bass. I mean in real life. Not on paper, and not in Spice or some other model.

Set up a controlled experiment and take measurements. Then post the results. That's how science works. Stop taking someone else's word for it, especially when you are taking that word out of context.

A bass only has a single ground point at the output jack. Every ground point in the bass is therefore at the same ground potential. You seem to be not understanding that. There are multiple components in the bass which must ground to that point. It doesn't matter how they do it, as there is a ground plane set up in the control cavity. Look at the photo of the Gibson Les Paul I posted.

Here's another example: carbon shielding paint. For shielding, it has a fairly high resistance. Yet, it works and does not generate any weird currents. For the noise hitting that paint, it's the path of least resistance to ground, even if it is a couple of ohms. The common return path the paint is connected serves as an adequate zero-voltage reference level.

Star grounding is for when there are powered circuits that use grounds as part of their circuit. As in a tube amp. You have multiple power supplies going on. You have the filament voltage, and the plate voltage, etc. And they all dump into ground. That's where the different currents on a SHARED ground come into play. To a 300v circuit, the 15v circuit is a lower potential.

A bass has none of that. The pickups are generating a meager current, and any RF noise that hits shields is shunted to ground. It does NOT produce a current on the ground plane.

If it did, then 50 years ago the same people who started star grounding amps would have done the same with guitars. I think Leo Fender and the rest were smart enough to know that. They didn't use star grounding because it's unnecessary.

I think the problem here is you understand a bit about this, but not enough to see where you are in error.

Since you like to point to the internet, lets take a hop over to Wikipedia. While it sucks of most things, the technical articles are usually quite good.

http://en.wikipedia.org/wiki/Ground_loop_(electricity)

A ground loop in a system which connects circuits designed to be at the same potential but which are actually at different potentials can be hazardous, or cause problems with the electrical system, because the electrical potential and soil resistance at different points on the surface of the earth can vary.

Notice it says "connects circuits designed to be at the same potential". There is only one circuit in the bass.

Further (emphasis added):

If two pieces of audio equipment are plugged into different power outlets, there will often be a difference in their respective ground potentials. If a signal is passed from one to the other via an audio connection with the ground wire intact, this potential difference causes a spurious current through the cables, creating an audible buzz at the AC mains base frequency (50 or 60 Hz) and the harmonics thereof (120 Hz, 240 Hz, and so on), called mains hum.

There's your ground loop. TWO pieces of AC powered gear, plugged into two different power outlets, and then connected together (i.e. THE LOOP) causes current to flow FROM ONE AC OUTLET TO THE OTHER via the circuit grounds. Humming at the main's frequency. Go back and see I said the same thing earlier in this thread.

If you read further in the Wiki article you will see that ground loops and star topology all have to do with noise from the power supply that powers the circuit. Basses have no such AC power supply in them. Batteries don't generate hum either.

We only have ONE circuit ground on a bass. The wires in the at circuit are just like the ground plane on a circuit board:

http://en.wikipedia.org/wiki/Ground_plane

In electrical engineering, a ground plane is an electrically conductive surface, usually connected to electrical ground.

A ground plane on a printed circuit board (PCB) is a large area or layer of copper foil connected to the circuit's ground point, usually one terminal of the power supply. It serves as the return path for current from many different components.

In a bass we have many different components connecting to a single ground plane which is generally made up of the shielding, which includes the potentiometer cans (backs).

These are tied together to form the ground plane, which then has a single connection to the circuit's ground, at the output jack. This then connects to the amp's power supply ground via your patch cord. Just as on a circuit board, there is a length of copper (wires) carrying the ground.

[warnergt]

Originally Posted by dmusic148

You know the answer-it's a short circuit. Current will flow in this circuit because there is a source with a clear +/-. No contradiction. Also no noise potential, as it's DC anyway.
Now, if I connected the battery + to the bridge, and battery - to my house AC ground, what would happen?
This is a much more realistic example.

You didn't answer the main question: why must a noise signal run to ground?
Why prevents a noise current from being induced between
the shield and the bridge? What if I have a wireless bass?
Where does the noise current go? Is the bass suddenly
immune to noise?

[SGD Lutherie]

Originally Posted by warnergt

You didn't answer the main question: why must a noise signal run to ground?
Why prevents a noise current from being induced between
the shield and the bridge? What if I have a wireless bass?
Where does the noise current go? Is the bass suddenly
immune to noise?

Why to you keep pressing return? The text will auto wrap.

What makes you think a noise current is produced between the shield and the bridge? It doesn't and you haven't proven otherwise.

Where do you get these ideas?

You don't understand what happens when you use a wireless system? The wireless circuit has its own ground reference. So does your cell phone. So does an automobile. None of them are connected to earth ground.

You really don't understand how that works?

[michaelandrew]

Um, yes, well, okay, I recently installed a new pre-amp (Audere Classic 4-band) and shielded the control and pick-up cavities in a Yamaha 765a (active) bass (there's a pair of threads about it here from a few days ago). I used conductive adhesive copper shielding foil for the cavity shields. The pots are grounded by contact with the copper foil (you can't solder to the pots Audere uses).

I also used a "star ground", of sorts, but not because of any concern about either "mythical", or real, ground loops; I just found it easier to solder the pick-up cavity, bridge, and pre-amp ground wires together and use a short "pig-tail" wire connection to the sleeve ground on the output jack.

As a practical matter, I have to agree with SGD Lutherie. Not that anything warnergt has said is strictly wrong - I'm an EE as well - it's just that the theory bears the usual relation to the practice - i.e. little or none to speak of.

If you use an ordinary DVM to measure the DC resistance between the sleeve ground on the output jack and any other point in the circuitry that's supposed to be grounded then, provided it's less than a few milliOhms, there won't be any trouble from ground loops, mythical or otherwise, in the bass.

You may, however, get noise (buzz, hiss, hum, local radio stations, etc.) from other sources, so this could continue to be a useful discussion, IMO, to try to get some kind of coherent, practical, understanding of electrical noise reduction in bass guitars.

(Now watch me get it from both sides )

[SGD Lutherie]

Originally Posted by michaelandrew

If you use an ordinary DVM to measure the DC resistance between the sleeve ground on the output jack and any other point in the circuitry that's supposed to be grounded then, provided it's less than a few milliOhms, there won't be any trouble from ground loops, mythical or otherwise, in the bass.

There you go. And that's something anyone can do. I'm also suggesting him to take a reading and see if there's any current flowing between say the bridge ground and the shielding, but I guess that's too much to ask for. Then, if you detect any current you have to show that it causes noise that you can actually hear.

There's the kicker... even if the grounds in the bass cause some kind of noise, which I doubt, the noise from single coil pickups, or even the unshielded wire from the pickups will swamp that other noise out of existence.

The same argument goes for the capacitance of the hookup wires from the pickups, etc. Once you factor in your patch cord, that's a moot point.

Regarding noise; at one time I had one of my Ricks totally shielded with copper foil. Both pickups were shielded and hum canceling, and wire from the pickups was coax. I did not have the bridge grounded, and the bass was dead quiet, even around light dimmers. Clearly no star grounding was used, since all the pots were sitting on copper foil. Dead quiet.

So it can be done. Currently my pickups use a Faraday cage style of shielding.

[millsbass5]

Just don't do anything stupid like this guy, okay? Seriously, it'll be alright.



http://www.youtube.com/watch?v=hrZLc9lqQM0

[SGD Lutherie]

Originally Posted by millsbass5

Just don't do anything stupid like this guy, okay? Seriously, it'll be alright.



http://www.youtube.com/watch?v=hrZLc9lqQM0

YouTube has convinced me that this is true:

Human Beings Are Getting Dumber, Says Study

These days being dumb doesn't kill you, like it did in the past.

[michaelandrew]

I do have a related question or two: There is some electrical noise - hiss/buzz, not hum - when the pick-up balance control is in either the "all neck/bass" or "all bridge/treble" extreme position. The folks at Yamaha say the pick-ups are humbuckers and they are shown as such on the schematic (two coils with opposite electrical polarity).

So why the noise when the balance is cranked either way?

I can't see what's in the "soap-bar" pickups, so I don't know the magnet position(s). Is it possible that it's a "phantom" coil configuration and could that cause noise when only one pickup is used?

[michaelandrew]

Originally Posted by millsbass5

Just don't do anything stupid like this guy, okay? Seriously, it'll be alright.



http://www.youtube.com/watch?v=hrZLc9lqQM0

Must be all this talk about "pot"s and "buzz"es

[millsbass5]

Originally Posted by SGD Lutherie

YouTube has convinced me that this is true:

Human Beings Are Getting Dumber, Says Study





These days being dumb doesn't kill you, like it did in the past.

Which makes it even funnier. And, the guy calling 911 was a cop!!! Which, BTW, makes me think it was the reason why he was a dumb-ass about the whole situation.....

[sledge641]

i had a similar problem with my Ibanez bass, my amp is plugged into a power strip as well as pedal board i would lower the treble and it got better but still buzz, long story short it was my ceiling fan making the noise i left the light on but turned off the fan and that stopped the buzzing completely give it a shot.

[SGD Lutherie]

Originally Posted by michaelandrew

I do have a related question or two: There is some electrical noise - hiss/buzz, not hum - when the pick-up balance control is in either the "all neck/bass" or "all bridge/treble" extreme position. The folks at Yamaha say the pick-ups are humbuckers and they are shown as such on the schematic (two coils with opposite electrical polarity).

So why the noise when the balance is cranked either way?

I can't see what's in the "soap-bar" pickups, so I don't know the magnet position(s). Is it possible that it's a "phantom" coil configuration and could that cause noise when only one pickup is used?

Humbuckers only get rid of the hum part. The buzzing stuff is electrical field noise. There's probably something getting unbalanced when the blend control is at the extreme positions. I've never heard of that happening, but I'm not familiar with their circuit (I'm assuming it has a preamp?)

I've seen some issues with Yamaha electronics over the years.

[SGD Lutherie]

Originally Posted by sledge641

i had a similar problem with my Ibanez bass, my amp is plugged into a power strip as well as pedal board i would lower the treble and it got better but still buzz, long story short it was my ceiling fan making the noise i left the light on but turned off the fan and that stopped the buzzing completely give it a shot.

Yeah, the treble control will boost the high frequency noise and make it more obvious. Things like light dimmers and motor speed controls (very similar circuits) put out a lot of noise that's very hard to block.

[warnergt]

Originally Posted by SGD Lutherie

...A bass only has a single ground point at the output jack. Every ground point in the bass is therefore at the same ground potential.

If this were true, a single point ground would not be necessary.
I would never make this assumption in a low noise circuit
design. This is the fundamental difference between what you
believe and what I believe.

Unless you have a noiseless, currentless environment or unless
you are using zero ohm superconductors to carry your signals,
no two ground points are ever at the same potential.
A quick Google search shows that I am in good company with
this belief.

From: https://passlabs.com/articles/ground-loops
"The key points to understand are that there is no such thing
as a perfect ground and that no two ground points within any
system are ever exactly equipotential to one another."

From: http://www.canadiancontrols.com/docu...ol%2050532.pdf
"When carrying current, no two points on the conductor are
at the same potential."

From: http://www.ieeta.pt/~alex/docs/appli...20handbook.pdf
"No two ground points have exactly the same potential."

This one is from a physics department (what do they know?):
http://www.physics.utah.edu/~kai/3610/Lecture24.pdf
"No two ground points are at the same zero potential."

From: http://www.qsl.net/kd6pag/usenet/Grounding.html
"No two points on Earth have the same potential
when currents are flowing between them."

From an electronic design magazine:
http://www.highbeam.com/doc/1G1-14007387.html
"In practice, however, no two points on a circuit's ground
plane are exactly at the same potential, and they generally
exhibit a nonzero impedance between them."

http://www.steven-stanley-bayes.com/...Musicians.docx
"NO TWO GROUNDS HAVE THE SAME POTENTIAL ENERGY
UNLESS CONNECTED WITH A RESISTANCELESS FLOW PATH "

[warnergt]

Originally Posted by dmusic148

Sure. But if all the metal parts that are likely to pick it up are securely grounded to a ground plane of any shape or size, all of that noise will follow the path of least resistance, which is to ground. It all ends up at the third lug of your power cord, which is what the - terminal of your guitar cable is attached to. Ground. Down the drain it goes, unless something is faulty. It doesn't go round in circles. It goes to ground.

Hey dmusic148, I stumbled across a quote written just for you.
It comes in a section called "0.2 - MYTHS ABOUT EARTH
GROUNDING AND WIRES" from Jensen Transformsers in
http://www.jensen-transformers.com/a...%20seminar.pdf
"Many indulge in wishful thinking that noise currents can
somehow be skillfully directed to an earth ground, where
they will disappear forever!"