Tuning Instability solution GCS-1 and maybe other tuneamatics

[rpjazzguitar]

In case this is helpful.

Some time back I posted about some tuning instability in my GCS-1. I've been having to retune, slightly, after a song or two. In contrast, my Yamaha Pacifica 012 stays in tune all day.

I finally had a luthier look at it, John Jordan in Concord CA, who I recommend highly.

John wiggled the bridge. He held it at each end. Then he simultaneously pushed one end toward the endpin and the other towards the nut, then the reverse. The bridge moved a surprising amount. John identified this as the likely source of tuning instability. He pointed out that the bridge on the Yamaha, a completely different design, won't budge at all.

The GCS-1 bridge, like a Gibson tuneamatic, slides onto the two posts, but the holes are, apparently, a tiny bit too big. The fact that it slides on and off so easily may mean that there's going to be a problem - the fit needs to be tight. As you move the strings when you play, there is force applied to the bridge. It moves a bit and then doesn't end up in the exact same place where it was when you last tuned up.

He said the pro solution is a bridge that locks onto the posts with a screw. He said there is a product called TonePro which does that. The screw goes through the side of the bridge and pushes against the post.

I don't know if the TonePro bridge would fit the GCS-1 posts. Are these things standardized? Also, presumably, it would require slotting the saddles to get the right string spacing, which I think would require some skill I don't have.

John mentioned that people with the right tools could tap the existing bridge to add the necessary screws.

I asked if I could just shim it. John seemed skeptical, but suggested that I could try plumber's tape.

But, I didn't have any on hand and was impatient. Impatience is not a virtue in most things and not this either, so I don't recommend what I actually did, even though it worked.

Loosen the strings enough, or remove them, and the bridge slides up, right off the posts. I then took tiny squares of duct tape and put them like little hats on the posts - and slid the bridge over them - pretty tight fit. Now, the bridge wiggles hardly at all and the guitar is staying in tune much better. You can see a tiny circle of the duct tape on top of the posts, but it's close to the bridge color and doesn't bother me. It could probably be cut out with a small, sharp blade.

John said that it's a common problem and that even Gibsons can have it.

He also raised the stopbar tailpiece, thereby reducing the break angle. I think that allows the strings to slide more easily over the saddles which may help with the feel of the action and tuning stability, but I'm not sure about that.

Anyway, I thought I'd mention it because it's no-cost and completely and easily reversible. Oh, and it solved the problem.

[sgosnell]

Actual duct tape should work okay. I wouldn't try gaffer's tape, which is often called duct tape but is different. Duct tape is aluminum, hard and stiff. It's designed to seal ducts, not to just hold stuff together.

[rpjazzguitar]

Actual duct tape should work okay. I wouldn't try gaffer's tape, which is often called duct tape but is different. Duct tape is aluminum, hard and stiff. It's designed to seal ducts, not to just hold stuff together.

What would the problem be with gaffer's tape, which I think is what I actually used?

[sgosnell]

It's soft and the adhesive is loose and sticky, and can ooze out and be a problem. It might work for you, but IMO actual duct tape would work better. Its available at home improvement stores, not too expensive. But if you don't have some already, buying one of the huge rolls they come in might not be worth the expense. I generally have some. It also works as shielding for solid-body cavities. Whatever works is good enough though.

[deacon Mark]

I would just replace the whole bridge and saddle be done with it.