Promotion Items

the KILN @Indiegogo
4hr Courses

Dear Friends, Guitaring Passionately has began its inaugural acoustic guitar making process in early 2017. Do stay tuned to the progress thru instagram and Facebook.

Check out our Price Busters

Learn practical guitar maintenance skills in our 4hr Courses. Brochure Download here

Monday, June 26, 2017

Guitar Myths #002 - Are acoustic guitars' tops really flat?

Flat acoustic guitar top… really?

Once again urban myths strike again.

After making the big decision to part with one's hard earned money, a guitar was purchased. It was all perfect… was it? Playing the brand new guitar in private, admiring its beauty, savoring its tone… suddenly a slight bulge about the guitar bridges' area was sighted. Perplexed by it, immediately turning to internet to seek for an explanation.

Most people fear the unknown. Needless to say, many guitar owners assumed the worse. As such, it triggered their paranoia quests for solutions to this mysterious phenomenon. So the million dollars question; Are acoustic guitar tops really flat? If it isn't, so the guitar is not in perfect condition, right?

Total String Tension

First let's take a look at how much force is acting on a 6-string acoustic guitar's top board when all six strings are fully tuned to standard tuning. In D'Addario's website, the force in both pounds and kg for each string is listed. Below is an excerpt from D'Addario's EXP PB 12/53 string's technical specifications. 12/53 gauge is chosen because of its commonality.

Taken from:

There is no rocket science in determining the total force acting on a guitar top board. Just add them up.

In KG; (E)10.6 + (B)10.57 + (G)12.9 + (D)13.03 + (A)12.74 + (E)11.05 = 70.89kg or 156.29lbs

How much does a regular dude weigh?

Thickness of Top Board

Next, we shall consider the typical thickness of acoustic guitars' top boards. There are actually many considerations in determining the thickness of an acoustic guitar's top board. It isn't practical to go at length about it herein for obvious reason. Lets' take the word of a guru, Ervin Somogyi as a good guide. He mentioned in one of his many articles the preferred top board thickness is 3/32" or 2.34mm in thickness. You can read his full article here:

We are going to rewind a little to figure out the reasons for guitar owners to assume that acoustic guitars' tops are flat.

Points of sale; firstly there is virtually no good reason for buying a guitar except for professional guitarists. We buy guitars on impulse, simple as that. Under impulse, no amount of intellect can help a guitar fanatic to discern facts from fiction. A guitar sales guy would say whatever the potential buyer wishes to hear. That includes generating an impression upon the potential buyer that the guitars in the shop are in perfect conditions. It isn't too hard to connect the dots right?

Acoustic guitars' top boards appear to be flat to our naked eyes. Most guitar buyers wouldn't question validity of this point. So it is not difficult for the sale guy to complete the sales with the buyer thinking and agreeing that the purchased guitar is in perfect condition which includes a perfectly flat top board.

Limited knowledge; while many guitar owners are passionate about playing guitars, however that has little to do with the motivation to learn adequately about guitar's construction. Flat Top guitar, this common jargon has convinced guitar owners that acoustic guitars' top boards are indeed flat or they must be flat. It is indeed factual that acoustic guitars' top boards are flat during the construction phase. All that will change when a constructed acoustic guitar gets into the quality control (QC) section. The freshly constructed guitar with a perfectly flatted top bulges immediately when the QC dude loads strings on it, for the purpose of inspection and setting up.

It isn't the end.

If this guitar gets shipped to regions with high humidity climate, the guitar continues to absorb moisture of the surroundings. Thus the bugle increases.

Answer to the million dollars question;

Lets' take a look at this picture.

Taken from:

So does that answer the question? Just do an image search with this phrase "bulge guitar top" on any search engine to enlighten your mind.

Summing UP

Bulged top board is not a defect. It is an inevitable usage outcome of ALL acoustic guitars. It is perfectly normal for acoustic guitars to have a bulged top when in normal use.

Earlier we have found out the total six string force, that is 70.89kg or 156.29lbs as well the typical thickness of acoustic guitars' top boards, that is 3/32" or 2.34mm. It is also a common knowledge that wood would compress or flex under force loading.

If we put these facts together, it is not hard to understand that acoustic guitars will bulge under normal usage.

When a force of 70.89kg is allowed to perpetually act on a piece of wood of 2.34mm thickness, how would this piece of wood remain unchanged structurally?

In addition, when an acoustic guitar has absorbed excessive moisture from its surrounding, it will also contribute to the bulge.

In closing, I would submit to all readers of this blog post that top board bulging in acoustic are caused by these factors,

1. String tension
2. Thin top board
3. Wood's natural compressible and flexible properties
4. Absorption of moisture

Don't loose sleep over your bulged acoustic guitars. They are in PERFECT conditions!

No comments:

Post a Comment