Help w/ EMG to Passive--no GD to bridge?

Tall Steve · Post by **Tall Steve** » 22 Apr 2014, 22:36

Buddy wants his pups changed from EMG to passive. Got all the guts out of his guitar and noticed there's no GD wire to the bridge. Are we gonna have to send it to a tech to route one out?

phatt · Post by **phatt** » 23 Apr 2014, 11:51

Usually a drilled hole from under bridge angled across to closest cavity is all that is required, assuming you have a drill?
Phil.

Tall Steve · Post by **Tall Steve** » 24 Apr 2014, 03:09

I have a drill, but it's not my guitar. I told the owner that's what would be required. It was a no-go. He wasn't too keen on putting a hole in his baby. Anyway, what is the reasoning behind leaving the bridge/strings ungrounded with active pickups? Does it prevent shock from the battery, or is it some other safety or noise concern?

bigorangefan79 · Post by **bigorangefan79** » 24 Apr 2014, 05:32

Passive pickups ground the strings in order to use the metal on the guitar and everything touching that metal (you) as part of the shielding. That is why hum increases when you are not touching the strings. You are no longer intercepting RFI and EMI. Active pickups are internally shielded and designed for very low noise, therefore the extra shielding is unnecessary. What type of guitar are you dealing with? Fender style guitars will not require any drilling to ground the strings.

Post by **The G** » 24 Apr 2014, 11:35

bigorangefan79 wrote:Passive pickups ground the strings in order to use the metal on the guitar and everything touching that metal (you) as part of the shielding. That is why hum increases when you are not touching the strings. You are no longer intercepting RFI and EMI.[...]

Actually, the hum decreases when you touch the strings or the bridge (if they're conneced to the ground) because you're an antenna. Touching the strings connects you-the-antenna to the ground and thus all the signals (actually, noise) you're providing as an antenna go to the ground.

Tall Steve · Post by **Tall Steve** » 24 Apr 2014, 14:22

Thanks guys! The guitar is an Ibanez shredder Paul with a locking bridge/stoptail. Owner says the EMGs keep it from being as versatile as he'd like. He wanted me to swap them for some legit, USA Seymours that currently live in a Washburn he bought for cheap on eBay. He probably paid the same for the whole guitar as the previous owner paid for the pups alone. Anyway, once I mentioned the drill, dude told me to wire everything back the way it was. Thanks again for your help! Seems I've got some soldering to do...

CHEEZOR · Post by **CHEEZOR** » 24 Apr 2014, 18:21

I have done this before in an LTD Les Paul shaped guitar. It was a pretty straight forward process if you have a drill bit that is long enough. I was in the same boat with EMGs and I wanted to put some passive pickups in. I think it sucks that the manufacturer doesn't drill the hole just in case you want to swap pickups, but that's another story. I would strongly recommend that your friend has someone drill that hole. It makes the guitar MUCH more versatile with the ability to change to the other 99% of (passive) pickups out there. I love the EMG active pickups, but I don't want all my guitars to have them. Tell your friend to stop being such a pansy about it and drill the hole. After all, its only a piece of wood.

Tall Steve · Post by **Tall Steve** » 25 Apr 2014, 04:11

But it's such a pretty piece of wood...

Out of curiosity though, where did you start your drill, and what did you use for ground? This guitar is an Ibanez a la LTD.

bigorangefan79 · Post by **bigorangefan79** » 25 Apr 2014, 04:30

ggedamed wrote:
bigorangefan79 wrote:Passive pickups ground the strings in order to use the metal on the guitar and everything touching that metal (you) as part of the shielding. That is why hum increases when you are not touching the strings. You are no longer intercepting RFI and EMI.[...]
Actually, the hum decreases when you touch the strings or the bridge (if they're conneced to the ground) because you're an antenna. Touching the strings connects you-the-antenna to the ground and thus all the signals (actually, noise) you're providing as an antenna go to the ground.

That's what I said. The "signals (actually, noise)" is called RFI and EMI. And the human body when touching the grounded metal is functioning as shielding shunting that interference to ground.

bigorangefan79 · Post by **bigorangefan79** » 25 Apr 2014, 04:45

Tall Steve wrote:But it's such a pretty piece of wood...

Out of curiosity though, where did you start your drill, and what did you use for ground? This guitar is an Ibanez a la LTD.

Most LP style guitars run the ground wire from the bridge post hole closest to the electronics cavity. Getting the threaded insert out of the body can be tricky if it's a really tight fit. If the threaded metal insert pulls out of the body, just mask the body around the hole, be careful not to let the bit touch the paint, and drill toward the cavity. Once you are through, just run a wire from the post hole to the cavity. make sure the wire is stripped back and touching the metal insert when you put it back in. Then solder the other end to the back of a pot. Get your meter out and check for continuity between the bridge and ground then put it back together.

CHEEZOR · Post by **CHEEZOR** » 25 Apr 2014, 17:19

bigorangefan79 wrote:Most LP style guitars run the ground wire from the bridge post hole closest to the electronics cavity. Getting the threaded insert out of the body can be tricky if it's a really tight fit. If the threaded metal insert pulls out of the body, just mask the body around the hole, be careful not to let the bit touch the paint, and drill toward the cavity. Once you are through, just run a wire from the post hole to the cavity. make sure the wire is stripped back and touching the metal insert when you put it back in. Then solder the other end to the back of a pot. Get your meter out and check for continuity between the bridge and ground then put it back together.

This all sounds right. I just wanted to add a couple things. Mine was a Les Paul body shape, so I had to remove the jack plate and unsolder the jack or unscrew it from the jack plate and pull it through the jack hole. Clear the area of wires (you can tape them out of the way). Now that you have the jack's hole showing, you have a clear shot to the bottom bridge post if you use a drill bit that is about a foot long. You'll need to remove the bridge post and the bridge post insert. The bridge post should unscrew easily and then you can remove the insert easily by putting something small in the insert. I used a screw, but anything the right size should work. The insert should be a cylinder shape with no bottom. So once you have an object in there all you need to do is screw in the bridge piece and it will pull the insert out.

If you don't understand what I'm talking about here are some videos that show a couple different ways of removing the inserts:

I'm sure both methods will work equally well. Just take your pick.

Once you have the insert out, then its just a matter of drilling from the jack cavity all the way to the bridge post hole. I put masking tape on the guitar top to line up drill bit so I could see if I was crooked. There are probably better ways. Mine worked out fine. But take your time with this part and get it right the first time. Mark the distance on the drill bit with some masking tape or something so you know when you should have hit the post hole or not. Basically, so you don't keep drilling if you missed the mark.

Let me know if you have any other questions.

Tall Steve · Post by **Tall Steve** » 25 Apr 2014, 18:49

Brilliant, CHEEZOR, thanks!

Post by **The G** » 26 Apr 2014, 12:33

bigorangefan79 wrote:
ggedamed wrote:
bigorangefan79 wrote:Passive pickups ground the strings in order to use the metal on the guitar and everything touching that metal (you) as part of the shielding. That is why hum increases when you are not touching the strings. You are no longer intercepting RFI and EMI.[...]
Actually, the hum decreases when you touch the strings or the bridge (if they're conneced to the ground) because you're an antenna. Touching the strings connects you-the-antenna to the ground and thus all the signals (actually, noise) you're providing as an antenna go to the ground.
That's what I said. The "signals (actually, noise)" is called RFI and EMI. And the human body when touching the grounded metal is functioning as shielding shunting that interference to ground.

Sorry, man, that's what I wanted to set right: the human body is an antenna. It is not the shield and it will never be.
If you're grounded, all the noise you're catching as an antenna is shunted to ground. If you're not grounded, the noise may find a way to the guitar's circuit.
When you move your finger close to a pickup, without touching it, the noise increases. You're the source. If you were a shield, the noise would not change, touching or no touching, because the strings are already grounded.

I'm trying to rephrase it better: the interference that is shunted to ground when touching the strings is indeed EMI, but is collected by the guitarist's body and passed to the guitar electrical circuit.

LATER EDIT
Just to have the definition here (Wikipedia):

Electromagnetic interference (or EMI, also called radio-frequency interference or RFI when in radio frequency) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.

RFI is a subset of EMI.