Replies to This Discussion

Permalink Reply by Leroy Beal on May 31, 2010 at 4:30pm

This is how.

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php...

Permalink Reply by Travis Gaines on June 1, 2010 at 1:53am

Do you have to use a metal bridge? If you don't I assume you just ground the pot to itself and the pup. I am a wiring noob. I do know how to solder though.

Permalink Reply by Leroy Beal on June 1, 2010 at 4:42am

Travis Gaines said:

Do you have to use a metal bridge? If you don't I assume you just ground the pot to itself and the pup. I am a wiring noob. I do know how to solder though.

You don't need to use a metal bridge if you can ground the wires somehow. A grounded metal string anchor or tailpiece would work. Without proper grounding you will probably be disappointed with the results.

Good luck.

Permalink Reply by Travis Gaines on June 1, 2010 at 1:43pm

last question: If I use a nail or a bolt for my bridge, I can just run a wire to that and use it as a ground?

Permalink Reply by Murray on June 1, 2010 at 2:57pm

Travis - short answer...'yes'.

Long answer follows...sorry, it's my nature...if only I could take that tendency and apply it to solos!!!

Basically the wiring to the amp needs signal and ground. Any other exposed metal parts usually get grounded also so they don't end up at some other signal level...two unpleasant signal levels we want to avoid are hum/noise and shock hazard. If they are NOT grounded, they can couple hum to single coil pups which seem to invite every opportunity for hum and noise.

I guess a metal bridge (or nut) is really essential for a magnetic pickup...or you would have difficulty grounding the strings. Completely isolating the strings electrically might seem like a guaranteed way to prevent them from ever becoming a shock hazard, but 1) you can't guarantee that, so it's safer to keep them grounded, and 2) the stringy li'l critters and your body act like antennas delivering signals to the pickup.

If metal items ARE grounded, it's a good idea to make sure all metal items are grounded together so you can't have two metal parts at different voltages, like metal strings one of your hands touches and a pot shaft with Telecaster-type metal knob in the other hand. The idea behind a 'star' ground is the shape...all separate metal items ideally have their own ground wires that all meet at a single point. Think 'star' as in the asterisk * above the '8' key on your keyboard, not like the star that has all its lines crossing at different in space...and not like making you a star and not like seeing stars...you've got a wiring problem if you see stars when you touch the metal parts!
OK, too much info, right? Of course a shock hazard doesn't automatically exist for no good reason at all...it happens because of bad wiring practices outside the instrument and risk of exposure depends on wiring practices inside the instrument.

NOT using a star ground (it's not always practical) doesn't guarantee you will have hum, but it's the best way to minimize problems. If it's never made a difference in your experience, just be happy.

Permalink Reply by Leroy Beal on June 2, 2010 at 3:57am

Travis Gaines said:

last question: If I use a nail or a bolt for my bridge, I can just run a wire to that and use it as a ground?

Yes.

This photo shows a ground wire coming up to the Allthread bridge on one of my lap steel guitars.

A grounded/shielded electronics compartment is highly recommended.

Like Murry said, a star ground is a good idea. I use it because it makes wiring a lot easier.

Permalink Reply by Travis Gaines on June 2, 2010 at 9:46am

Thanks for all the input. I have a metal bracket from a car seat and a metal tube I was going to use for the bridge. I will just run a ground wire to the bridge base through the lid. I will try and get the compartment shielded at some point. This is my first foray into an electric cbg, and only my third build. It seems I still have much to learn.