Powered electronics need bridge ground?

[DaveCustomMade]

I got the 3.4 A/P preamp (Bartolini) and had someone at the local music store hook it up. However, he was uncertain if the ground wire was needed [attached under the bridge]. The instructions didn't call for it, however, he hooked a wire up anyway, and it is currently unattached, but can be if it is needed.

So the question is, for this preamp, do I need to have the wire going under the bridge, or is it best to NOT have it?

Thanks!

[Clark Dark]

in my experience only the active EMG's didn't require the ground wire to be connected..and it's expressly written in the installation instructions for EMG active pup's

[line6man]

This guy at the music store is completely incompetent if he did not know whether the bridge should get grounded or not.

There are only a couple of situations (at least that I know of) in which a bridge would be left un-grounded:

1. Some active pickups do not require a bridge ground, though it certainly does not hurt to ground it anyways. (You have passive pickups btw.)
2. Sometimes when you have single string bridges or wooden bridges that are difficult or impossible to ground, the ground wire may be left unconnected.
3. I've heard of one or two guys that chose not to ground their bridges because they were terrified of being exposed to dangerous voltages if their amp malfunctioned or were connected on a different phase from their other gear or something of the sort.

[mongo2]

IME, Bartolini passive pickups do not require the bridge to be grounded for noise-free operation.

[line6man]

Originally Posted by mongo2

IME, Bartolini passive pickups do not require the bridge to be grounded for noise-free operation.

There is no reason not to ground anyways.

[seanm]

Originally Posted by line6man

There is no reason not to ground anyways.

Are you sure about that? If the active circuit is not designed to handle the surge from a possible static discharge from your body, you could possibly blow something.

That said, you will usually get away with it.

[line6man]

Originally Posted by seanm

Are you sure about that? If the active circuit is not designed to handle the surge from a possible static discharge from your body, you could possibly blow something.

That said, you will usually get away with it.

Um, no offense but that is one of the dumbest things I have ever heard.

That is exactly the reason you have ground points to begin with.

The actual definition of a ground from wikipedia:

Electrical circuits may be connected to ground (earth) for several reasons. In mains powered equipment, exposed metal parts are connected to ground to prevent contact with a dangerous voltage if electrical insulation fails. A connection to ground limits the voltage built up between power circuits and the earth, protecting circuit insulation from damage due to excessive voltage. Connections to ground limits the build-up of static electricity when handling flammable products or when repairing electronic devices. In some telegraph and power transmission circuits, the earth itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor.

For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability in order to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard.

The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in vehicles such as ships, aircraft, and spacecraft may be spoken of as having a "ground" connection without any actual connection to the Earth.

[seanm]

Originally Posted by line6man

Um, no offense but that is one of the dumbest things I have ever heard.

That is exactly the reason you have ground points to begin with.

The actual definition of a ground from wikipedia:

Electrical circuits may be connected to ground (earth) for several reasons. In mains powered equipment, exposed metal parts are connected to ground to prevent contact with a dangerous voltage if electrical insulation fails. A connection to ground limits the voltage built up between power circuits and the earth, protecting circuit insulation from damage due to excessive voltage. Connections to ground limits the build-up of static electricity when handling flammable products or when repairing electronic devices. In some telegraph and power transmission circuits, the earth itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor.

For measurement purposes, the Earth serves as a (reasonably) constant potential reference against which other potentials can be measured. An electrical ground system should have an appropriate current-carrying capability in order to serve as an adequate zero-voltage reference level. In electronic circuit theory, a "ground" is usually idealized as an infinite source or sink for charge, which can absorb an unlimited amount of current without changing its potential. Where a ground connection has a significant resistance, the approximation of zero potential is no longer valid. Stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard.

The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in vehicles such as ships, aircraft, and spacecraft may be spoken of as having a "ground" connection without any actual connection to the Earth.

Sorry. I work with hardware guys and they specifically warned me against this. I will let them know they are wrong

[walterw]

Originally Posted by seanm

Are you sure about that? If the active circuit is not designed to handle the surge from a possible static discharge from your body, you could possibly blow something.

sorry, i'm with line6man on that one, that's just silly. a system that can't handle getting touched by a human being has no business inside an instrument.

now if you're super paranoid about yourself getting shocked when touching say, your strings and a microphone (the only reason EMG says not to ground the strings), you can use a big capacitor, like 1 or 2 uF, 4-500 volts, in-line to ground as a blocker to allow the hum to get bled off while blocking any DC.

[mongo2]

Originally Posted by line6man

There is no reason not to ground anyways.

Well, there is that whole saving your life in case of a fault in a piece of equipment or the house wiring that shocks your tookus into the next county when you touch the strings and kiss the mike at the same time thing that may come in handy.

[walterw]

Originally Posted by mongo2

Well, there is that whole saving your life in case of a ground fault in a piece of equipment that shocks your tookus into the next county when you touch the strings and kiss the mike at the same time thing that may come in handy.

you mean like I just described in the post before yours, along with the solution?

[mongo2]

Originally Posted by walterw

you mean like I just described in the post before yours, along with the solution?

Didn't read it. But yep, I installed my first snubbers in the early '70s. No bridge ground at all is easier when noise isn't an issue.

I find something inherently kludgy about a system that uses the operator's body as an EMI shield.

[ddnidd1]

Originally Posted by seanm

Are you sure about that? If the active circuit is not designed to handle the surge from a possible static discharge from your body, you could possibly blow something.

That said, you will usually get away with it.

Where does the static discharge go when you touch the metal knobs attached to the metal pots that are directly in the active circuit?

[line6man]

Originally Posted by ddnidd1

Where does the static discharge go when you touch the metal knobs attached to the metal pots that are directly in the active circuit?

It gets grounded.

The transistors in your preamp only "see" the input from the pickups.

You can apply a nearly infinite voltage and current load to ground without damage to any component of the preamp. THAT IS WHAT A GROUND IS FOR. Any kind of static charge wants to find the quickest path to the earth, which is why you have a ground in place.
Should there be any stray currents introduced into the circuit, they will find their way to ground, away from any components.

Think of the anti-static wristbands you wear when dealing with computers. If there is a static discharge from your body, it will make it's way to ground through the wristband before causing damage to any components.

Also think of lightening. When lightening strikes, it is "searching" for the quickest path to the earth, which is why is tends to strike metal objects. The current is diverted to the earth fastest through something that is grounded.

[SGD Lutherie]

Originally Posted by seanm

Are you sure about that? If the active circuit is not designed to handle the surge from a possible static discharge from your body, you could possibly blow something.

That said, you will usually get away with it.

If you had a static charge in your body, and your strings are grounded, it will discharge to ground, not the preamp.

The reason for string grounding is because the strings act as antennae and pick up noise.

It has nothing to do with the preamp.

.

[mongo2]

Originally Posted by SGD Lutherie

The reason for string grounding is because the strings act as antennae and pick up noise.

Where did you get that from?

[M0ses]

Originally Posted by SGD Lutherie

The reason for string grounding is because the strings act as antennae and pick up noise.

Or, perhaps, maybe the humming could be because the pickups (which just happen to be connected in some way to the output) are, umm, I don't know, picking up electrical interference??

The things some people get in their heads.

[ddnidd1]

Quote:
Originally Posted by ddnidd1 View Post
Where does the static discharge go when you touch the metal knobs attached to the metal pots that are directly in the active circuit?

Originally Posted by line6man

It gets grounded.

The transistors in your preamp only "see" the input from the pickups.

You can apply a nearly infinite voltage and current load to ground without damage to any component of the preamp. THAT IS WHAT A GROUND IS FOR. Any kind of static charge wants to find the quickest path to the earth, which is why you have a ground in place.
Should there be any stray currents introduced into the circuit, they will find their way to ground, away from any components.

Think of the anti-static wristbands you wear when dealing with computers. If there is a static discharge from your body, it will make it's way to ground through the wristband before causing damage to any components.

Also think of lightening. When lightening strikes, it is "searching" for the quickest path to the earth, which is why is tends to strike metal objects. The current is diverted to the earth fastest through something that is grounded.

I do understand the concept. My post at the top was just a snarky response to the idea that grounding the strings could damage the electronics.

[line6man]

Originally Posted by ddnidd1

Quote:
Originally Posted by ddnidd1 View Post
Where does the static discharge go when you touch the metal knobs attached to the metal pots that are directly in the active circuit?



I do understand the concept. My post at the top was just a snarky response to the idea that grounding the strings could damage the electronics.

Ah, ok.
Usually emoticons are used with posts like that, so we know when you're being sarcastic.

[DaveCustomMade]

Okay, so yesterday afternoon, I went ahead and contacted the ground wire underneath the bridge . . . . . which I believe has been discussed as "better to do", unless I miss it.

I do appreciate all the posts thus far. Any other bits of info is welcome.