How flat is your flattop's top?

[sean79]

One of the things I would like to do is lower the action on my acoustic guitar (an early 90s Korean made Ibanez). I've done some searching here and elsewhere on how to approach it, but I've run into a concern.

My nut relief seems to be okay. The neck relief is acceptable. I thought the next step might be to remove the saddle and sand some off the bottom. However, the saddle doesn't stick up out of the bridge very much. I guess I was worried about string break angle over the saddle, so I did some more searching.

Something I read somewhere suggested that a flattop's top could lift and bulge away from the bracing - causing too-high action. I'm not sure that's what's going on here. From what I can tell (after sticking my hand through the soundhole), the top bracing seems to be intact. However, when I place a ruler across the guitar's top - right behind the bridge - it does not lay flat. The center of the guitar seems to be about 1/8 inch higher than the sides.

I read that many "flattop" guitars are built with arched top bracing, but I didn't find anything saying how much arch is built into these "flat" tops. Does 1/8 of an inch seem reasonable, or is this indicative of a problem?

How much arch do you guys have in your flattops?

All I really want to do is lower my action, but I don't want to screw with it if I have other problems. Thanks.

[westex93]

To quote Norman Blake: "Never trust a guitar that doesn't have a belly." Most guitars, unless they're built like a tank, will develop a belly behind the bridge. Again, this applies more to lightly built guitars.

Now, your Korean Ibanez would not typically fall into that category, IMO, and would be a much heavier built guitar. The first step, which you have done, is to check for any loose braces, etc. If the soundbox is structurally OK and the guitar is properly humidified (it is properly humidifed, right?) but the action is still too high, then you may be getting into neck reset territory. You've already said that the saddle is sitting pretty low. Thing is, I don't know that the value of that Ibanez would honestly warrant the expense of a neck reset unless the guitar has some sentimental value or something. Maybe you have an especially good one, I dunno.

A couple more questions. How long have you had the guitar? Did the problem just show up? Was it a sudden change? Does the guitar have a solid top?

These things are just hard to evaluate over the 'net without having the guitar on the bench, though.

[westex93]

One more thing. Going back to the jist of the question, re: lowering the action, what are your specs right now and what are you trying to achieve? How did you measure your nut action? Neck relief? 12th fret action? Are you pretty close to what you're trying to achieve and just wanting to dial it in more or are you a mile off?

Best bet is likely to have a local setup and repair guy take a look at it.

But, once again back to your other question, a belly bulge in itself it not directly a concern. But it may be. Or not. Maybe.

[sean79]

Thanks, Wes. I've owned the guitar since new - maybe sixteen years or so - but I haven't played it all that much. The action has always been a little high - it's not a new thing.

I can't give you measurements for action/relief. I used to try to measure stuff like that on my electrics, now I just usually eyeball it. Checked the nut relief by fretting at the second fret and checking the space between the strings and the first fret. Checked neck relief by fretting the first and last frets and checking the spacing at the ninth (I could probably straighten it some and take a little relief out of it). The overall action around the 12th is definitely higher than on my electrics (and a lot higher than at the lower frets), but I didn't measure it.

I'm pretty sure it has a laminate top, sides, and back. It probably is built pretty stout. There's no real sentimental value attached to this thing, so dumping a bunch of money into it doesn't make any sense.

I wish I had some measurements to give you. I'm not really a mile off from where I want to be, but I wish it played a little more like my electrics. Switching to lighter strings might help playability some, too. Our local music store doesn't have much of a selection in acoustic string gauges.

The saddle has never been lowered - maybe I could take a smidge off the bottom of it and straighten that neck out a little? Should I try one at a time?

Thanks, again, for the help.

[Tim Bowen]

Definitely pursue the technical suggestions here, which are quite good.

Mine is a tangent. With the exception of straight up bluegrass stylists, every working acoustic-electric player I know that has done this for ten plus years has low action that buzzes like crazy as played acoustically, but translates buzz-free as amplified. This may or may not address your concerns on a peripheral level, but if so, take note. If you don't believe me, ask Tommy Emmanuel. By his own admission, his guitars sound horrible acoustically, and buzz like there's no tomorrow. You can set up an acoustic guitar to be acoustic, or you can set it up to be acoustic-electric.

[sean79]

Thanks, Tim. I didn't know that. Right now, this thing is a flat-out acoustic guitar, but I have been thinking about electrifying it. Really appreciate the info.

[westex93]

Originally Posted by sean79

Switching to lighter strings might help playability some, too.

The saddle has never been lowered - maybe I could take a smidge off the bottom of it and straighten that neck out a little? Should I try one at a time?

Get the neck where you want it before you touch anything else. Attempt to dial in the neck relief with the truss rod. Just go slow and careful - truss rods CAN break, so when in doubt, stop. Once the neck is dialed in, then you may be able to lower the saddle some. Sounds like you don't have much to work with there, the way you described the saddle. If you do attempt this, the normal method is to pull the saddle and sand from the bottom on, say, a piece of 220 or 320 grit or so stuck to a flat surface. Go slow. It's easier to take material off than put it back on.

My basic setup method goes something like - neck relief, nut action, saddle height and intonation. In that order.

And, sure, switching to lights should help your action, but you may lose some tone and volume in the trade-off. All you can do is try it and see if the trade-off is worth it to you.

On a more expensive guitar, I would still investigate a neck reset based on your description, but a couple of tweaks may get your action down closer to where you want it.

[Buckocaster51]

find yourself straightedge about 24" long

put it on the fingerboard

let us know where the bottom edge of the straightedge hits the bridge.

Frank Ford's most excellent site, frets.com, is the absolutely GO TO place for all questions concerning acoustics.

It's the cat's pajamas!

[sean79]

Originally Posted by Buckocaster51

find yourself straightedge about 24" long

let us know where the bottom edge of the straightedge hits the bridge.

Well, the only straightedge I could find (without leaving the room) is just under nineteen inches. It smacks into the rosewood bridge about 1/32 below the top surface - at least in the middle of the fretboard it's like that.

Do any of you guys know where I left my allen wrenches?

[teleamp]

Originally Posted by sean79

... It smacks into the rosewood bridge about 1/32 below the top surface - at least in the middle of the fretboard it's like that. ...

Neck reset.

[westex93]

Yep, that's definite neck reset territory. But since we've already determined the guitar is probably not worth the investment of a neck reset, I'd go back to the above recommendations if the action is problematic for you. You may not get it where you want it but there may be room for improvement and some small gains may be made. Be aware, though, that when you go to lower the saddle height (after the neck is dialed in, remember?) that a too-low break angle can possibly result in some buzz, too.

[Buckocaster51]

An adventurous person can lower the bridge.

I've done it with a belt sander.

Then you may have to, or may not have to, deepen the saddle slot and, of course adjust the saddle.

But you may not be adventurous.

Have fun whatever you decide to do.

[sean79]

Thanks again to all who have responded.

Wes, I just tweaked the truss rod some - trying to get this neck dialed in. It doesn't appear to have removed much of the relief, but I think I'll let it sit for now and check it tomorrow. Do I really need to let it sit, or should I see most of the impact right away? How much of a turn do you put in an acoustic guitar's truss rod at one time?

Originally Posted by Buckocaster51

An adventurous person can lower the bridge.

Did you just remove the bridge, sand the bridge, and clamp and glue the bridge back in place?

[westex93]

Without having the guitar in hand, best advice I can give is just take it slow on the truss rod and play it safe. Small moves. I can't tell you how much, it's more of a feel thing. Just don't go crazy and strip or break a rod. I know I didn't specifically say so before, but release the tension off the strings before tweaking the rod, then tune 'er back up to check.

[sean79]

Originally Posted by westex93

I know I didn't specifically say so before, but release the tension off the strings before tweaking the rod, then tune 'er back up to check.

Got it.

When I tune it back up, will I see the change already? Or, do I need to let it sit for a while? I only turned it about 1/4 turn - no real noticeable change.

[rangercaster]

if the above doesn't work, i would also attempt to humidify the crap out of it ...