Emerald X-20 Opus

[Redduc]

My Emerald X-20 has developed a belly bulge of about .25”, the result being a higher than ideal action. Has anyone else had this problem? I bought this guitar used and I believe it had this condition when I bought it, I just thought the action was a bit high as the preference of the previous owner. I never put a straight edge on the face of the guitar. In fact I only just found out that the face was flat when built.

Is there any knowledge of a way to return this to its original form or closer to it than it is?

Ian

[BlueStarfish]

You'll probably get the best advice if you directly contact Emerald.

That said, you should be aware that the tops on Emerald guitars have a very different design than the tops on pretty much every other guitar I've ever seen. From the factory and by design, the Emerald tops are concave (that is to say, bellied in), whereas every other guitar I've ever seen is convex (that is to say, domed out). This results in about 1/8" or so more height between the top and the strings at the saddle than you are probably accustomed to. It's certainly possible your guitar has a defect, but it's also possible it's just a high (and easily fixable) action, or maybe too much neck relief, on a guitar that is otherwise in perfect shape.

Without seeing some pictures and measurements on your guitar, I can't say what's up with it. But I'll give you the measurement on my X20 so you can compare it. Mine measures just shy of 0.500" from top to string at the saddle. Whereas my McPherson Sable (with a more typical convex top contour) measures just a smidge over 0.375" for the same measurement. The actions on both of those guitars are comfy at about 0.093" at the 12th fret for the 6th string.

[mountainmaster]

My X20 also has a bulge of several millimeters (measured behind the saddle). Convex that is. The action is fine and has not changed over time. So I believe the bulge must have been there from the beginning.
This guitar is a nylon string. It has never had to endure any high tension from steel strings which could have caused a straight top to bulge.

It would be strange for a carbon fiber guitar to develop a bulge over time. My main reason for switching to CF was to never have to deal with something like that ever again. And so far it has worked out well.

[DDW]

There are reports of this happening to some of the early Ekoa guitars from Blackbird. Carbon structures can move around over time depending on how stressed they are. Being a new material for guitar construction (compared to wood) I think builders are still learning.

[Redduc]

I am speaking with the factory, I believe it will be mentioned to Alistair next week. The guitar is 5 years old so well beyond any warranty, and I’m really not sure there is any corrective path given the material and construction.

The action is just a little high at 0.11”/0.08”, which is why I just played it and didn’t bother too much, but I enjoy the guitar so much I thought I’d see if I could fine tune the action, and that’s when I discovered the bulge.

The first fret action is spot on and the relief is 0.006”, so I’m sure the issue isn’t there. I’d post a picture of the bulge, but I don’t seem able to figure out how. The center of the face, just behind the bridge is about 0.25” higher than the outside edges. Definitively a convex face.

Assuming the bulge doesn’t continue to grow, the fix is to make an adjustment at the saddle, which will be quite simple.

If the guitar was newer and the carbon potentially not post-cured, there might be a way to clamp the belly flat and run a high-ish temp post cure cycle. It’s a high risk proposition, with a very low chance of a result, particularly as I don’t know the resin system or cure cycles and Emerald keep the materials and process closely held.

I’ll see if Alistair has any suggestions, but I think a saddle adjustment is coming.

Ian

[Redduc]

This might link to a couple of photos.

https://www.dropbox.com/scl/fo/ho8fb...o6vi1lnbq&dl=0

Ian

[mountainmaster]

I checked my steel string X30 and it has a bulge just as high as yours.

The action was quite high when I received the guitar new from Emerald. I immediately lowered the saddle to my preferred height. This is what I always do with new acoustic guitars so it did not set off any alarms.

The action has not increased since then, which leads me to belief that like the top of my X20 it must have been convex from the start.

You may want to simply lower the saddle and be done with it.

[mountainmaster]

And for good measure I also checked my X7 which also has the bulge. It is somewhat lower but clearly visible. So by now I am convinced that this is totally normal for Emerald guitars.

[Redduc]

Originally Posted by mountainmaster

And for good measure I also checked my X7 which also has the bulge. It is somewhat lower but clearly visible. So by now I am convinced that this is totally normal for Emerald guitars.

It has been confirmed by Emerald the my X20 should have a flat face, at least it would have started out that way.

Adjusting the saddle will be no problem, my concern is that the face may continue to move, but I think I can help prevent that by backing off the string tension when it goes in to the case.

Once the action is lowered, just a little bit, it will play beautifully, feel great in my lap, and sound fantastic! This guitar is really growing on me every day!

Thank for sharing all your thoughts and experience.

Ian