Hollow vs Semi-Hollow and humidity

[JohnW63]

I have been wondering if a semi hollow guitar would be less likely to have the top move, due to changes in humidity or if I forget to soak the sponge in water ?

 

[txbumper57]

The semi Hollow would be less likely to move. The semi hollow actually has a block that connects the top and back of the guitar down the center of it. The pickups, Bridge, and sometimes the tailpiece all mount to the block through the outside of the guitar. The center block can be from 4-8 inches wide give or take. The hollow areas are from the outer edges of the center block to the outside edge of the guitar. So you basically have a solid body where the bridge and pickups mount. You still have to worry about proper neck angle with a semi hollow but you wont have to worry about the top sinking under the bridge. The center block also makes them far more resistant to feedback as well.:single_eye:

 

[GAD]

Unless it's a high-end carved archtop, the front/back are laminate (think plywood), and humidity really isn't a problem.

I used to obsess over humidity on all my semi-hollow and hollow-body guitars, but they're all laminates. Now I only obsess over my acoustics in regards to humidity.

 

[JohnW63]

GAD,

My NS X-175B moves a good amount. Besides changing the tuning, ( flat or sharp depending on which direction it is going ), I think it changes the string height enough to give me a fret buzz on about the 6th or 7th fret. We have storm clouds around, right now, and it's 35% RH. Normally, it's in the low 20s or even lower. My digital meter goes to "LL" when it drops to something below 20RH. I call it "Ludicrously Low".

 

[GAD]

GAD,

My NS X-175B moves a good amount. Besides changing the tuning, ( flat or sharp depending on which direction it is going ), I think it changes the string height enough to give me a fret buzz on about the 6th or 7th fret. We have storm clouds around, right now, and it's 35% RH. Normally, it's in the low 20s or even lower. My digital meter goes to "LL" when it drops to something below 20RH. I call it "Ludicrously Low".

You sure that's the top and not the neck? I see neck movement in some guitars (particularly ones with one-piece necks) during humidity changes - even solid bodies. FWIW humidity here often ranges between 10% and 90% based on conditions thru-out the year. I've owned a variety of semi and fully-hollow guitars and I've never seen movement that I could not immediately attribute to the neck.

Now, having written that, laminate is still wood, and the wood inside the guitar isn't protected like the finished outside is, so I'm sure humidity can affect it. I'm just saying I've never seen it first hand. I've also never owned an X175B, so there could be something about them that makes them more susceptible than the Starfires and Gretsches I've owned.

I should also state that I always store my guitars in the case and I do treat the fretboards with bore oil, both of which may have some impact as well.

 

[JohnW63]

Given my F47R top moves in the humidity, as measured with a straight edge, I assumed ( I know ) that the archtop would also move under the same conditions. I may take the 175 to a repair guy and have him check that 6th or 7th fret for being down on the fret board correctly.