Belly-up vs belly-down bridges; the rationale?

[Gilliangirl]

Struma6 posted this in the lounge and I don't know the answer so thought maybe one of you would know?

[J-1854Me]

Struma6 posted this in the lounge and I don't know the answer so thought maybe one of you would know?

 

Karen,

 

I think the reason that Gibson used the reverse belly bridge was primarily to distinguish their design from that used by Martin, which is 'belly-down'. I believe that change came about in the late 30s or early 40s.

 

But nevermind, you still see both designs in use by Gibson even now, although the "traditional" look is the reverse belly.

 

Fred

[dhanners623]

I heard the same thing; it was done to distinguish Gibsons from Martins. I'm no expert, but I can't see any structural or tonal reasons for the reverse belly.

[Red 333]

The Gibson belly up bridge is meant to prevent the bridge from collapsing below the soundhole; the extra wood between the saddle and soundhole provides more surface over which to distribute the strings' pressure.

 

In theory, the Martin belly down bridge works the opposite way; the extra gluing surface provided by the belly prevents the bridge from lifting behind the pins. There may be some merit to this idea--for many years, Gibson used pearl dot-covered bolts at either end of the saddle near the pins to prevent the bridge from lifting there (today those pearl dots are merely ornamental).

 

That's the theory as I understand it, anyway. I don't know for sure if those explanations are true--I wasn't there when Gibson or Martin made the decision to go belly up or down.

 

Here's another thought: Martin began using their belly down bridge in 1930. Gibson didn't begin to use their belly up bridge for at least another two decades, so I'm not sure reversing the belly's direction just for sake of a visual differentiation is the explanation for Gibson's rationale, as the non-belly bridge Gibson was using would have been visually different already. That's just my opinion, though. I don't have any historical reference to back that up.

 

Interesting topic. I hope someone can shed some additional light on it.

 

Red 333

[E-minor7]

This area is about mass and the only rationale I can think of, is that the lower-b. bridge leans towards the top-zone above and between the lower bouts, which is where most of the sound is generated.

I'm almost convinced the difference is immeasurable. The aesthetics is an another thing. Always found the lower-b. bridge more streamlined and had to get used to 'the other way around'. As if it got a bit tight towards the s-hole. Anybody recognize this?

 

 

[BigKahune]

... Interesting topic. I hope someone can shed some additional light on it. ...

 

+1

 

JT might be able to shed light on this topic. Hope he checks in.

[Rambler]

The Fab Flats book says it s was done as a hedge against bellying--but that may be in reference to Gibson's rectangluasr bridge--not the Martin belly-down design.

[jt]

Gibson actually introduced the belly-dwon bridge before Martin did. Here's my circa 1928 L-1:

 

 

Then, as we all know, Gibson used the rectangular bridge through the 1930s (plus the mustache bridge on the SJ-100, SJ-200, and J-55). In 1943, a very Martin-like belly down bridge (though more beautifully carved, imho) appeared on the SJs (and on at least one J-45s). Here's a first batch, FON 910, rosewood SJ:

 

 

Gibson clearly knew how to make a nice belly-down bridge when it introduced the belly-up bridge circa 1950. And, those belly-down bridges on the SJs worked quite nicely (and better than the rectangular bridges according to my co-author Willi Henkes). So, I'm convinced that Gibson went the belly-up route to distinguish itself from Martin.

[retrorod]

Good info and reasoning, jt.

Just curious about your 1928 L1. That is quite an unusual bridge style for Gibson. How can you be certain that it is original to the guitar and wasn't redone at some point?

...Rod

[Gilliangirl]

Excellent info, thank you everyone for the replies. I learned something!

[jt]

Just curious about your 1928 L1. That is quite an unusual bridge style for Gibson. How can you be certain that it is original to the guitar and wasn't redone at some point?

...Rod

 

It's original and common to the L-1s, L-0s, and NLs of that year. For confirmation of originality, I offer this:

 

 

And, you can read a bit more about my guitar here.

[J-1854Me]

...Also, Karen, the reverse- belly bridge is more aerodynamic.

 

Like Keds sneakers.

 

You can play faster, run across stage quicker, and (best of all) jump higher when playing!! (I think Pete Townshend practiced on Gibsons with reverse-belly bridges...)

[Gilliangirl]

...Also, Karen, the reverse- belly bridge is more aerodynamic.

 

Like Keds sneakers.

 

You can play faster, run across stage quicker, and (best of all) jump higher when playing!! (I think Pete Townshend practiced on Gibsons with reverse-belly bridges...)

ROFL! Fred you wouldn't be making this up now, would you?

[J-1854Me]

ROFL! Fred you wouldn't be making this up now, would you?

 

Karen, nothing is more serious than the disposition and design of bridges and their effectiveness for their intended design. Nor is it advisable to diss Pete. (I think I'll go play 'Pinball Wizard' on an appropriate guitar...)

 

Fred

[retrorod]

It's original and common to the L-1s, L-0s, and NLs of that year. For confirmation of originality, I offer this:

 

 

And, you can read a bit more about my guitar here.

'I See',I have to admit, the Xray pic is rather 'revealing'

So basically that bridge design is quite rare. That is a cool guitar. Gives me chills,thinking about the Robert Johnson connection.

Good stuff! When do expect your book to be ready? I,for one, will definitely buy a copy...Rod

[jt]

When do expect your book to be ready? I,for one, will definitely buy a copy...Rod

 

Thanks! Almost done. Working on the last chapter, talking with a graphic designer about layout, and talking with PBS about a documentary. Lots of news, soon.

[Red 333]

Thanks! Almost done. Working on the last chapter, talking with a graphic designer about layout, and talking with PBS about a documentary. Lots of news, soon.

 

 

Really looking forward to it.

 

jt, after having examined so many 1940's era Gibsons, have you seen much difference between the mechanical integrity of the rectangular bridges used on the J-45, and the belly down bridges used on the Souther Jumbos? Do the rectangular bridges tend to lift or collapse more, or do the guitars tend to show any characteristic conditions as a result of having a rectangular bridge? Also, did the SJs receive a larger bridge pad as a compliment to the larger bridge? If so, can you infer what effect if any the larger bridge and pad may have on sound?

 

Red 333

[jt]

Really looking forward to it.

 

jt, after having examined so many 1940's era Gibsons, have you seen much difference between the mechanical integrity of the rectangular bridges used on the J-45, and the belly down bridges used on the Souther Jumbos? Do the rectangular bridges tend to lift or collapse more, or do the guitars tend to show any characteristic conditions as a result of having a rectangular bridge? Also, did the SJs receive a larger bridge pad as a compliment to the larger bridge? If so, can you infer what effect if any the larger bridge and pad may have on sound?

 

Red 333

 

Thanks, Red!

 

I haven't been able to detect any difference. My co-author (and genius guitar builder) Willi Henkes says that he can hear a very subtle difference between the belly vs. rectangular and that the belly bridges sound better under hard flatpicking. My ears just aren't that good! Fortunately, I'm a fingerpicker. In any event, the guitars have the same bridgeplate regardless of bridge and we've noticed no difference in pulling up, etc.

 

BTW, some SJs, like my 1943, had the rectangular bridge:

 

[retrorod]

My Gawd, jt.....That is one beautilicious Banner SJ...The absolute epitomy of Gibson acousticdom! Now please excuse me while I mop the 'drool' up from the floor...

[jt]

My Gawd, jt.....That is one beautilicious Banner SJ...The absolute epitomy of Gibson acousticdom! Now please excuse me while I mop the 'drool' up from the floor...

 

Thanks, Rod! I am rather fond of it. AFAIK, It's the only Banner Gibson ever inspected twice. For the book project, I tracked down the original 1943 flattop inspector and asked her to reinspect my guitar. It passed, again:

 

[SuperG]

Interesting topic. I've always been curious about why some otherwise similar belly-up bridges have their pins set way back (like the pictured J-185) and some are in the center (like this sunburst J-45). Any background on this variation?

[jt]

I don't have knowledge of why Gibson instituted that change and my knowledge of Gibsons really ends in 1945. But, I can think of 2 reasons for moving those pins: 1) having the pins that far back reduces the break angle over the saddle and 2) having the pins that far back increases the risk of a split in the bridge.

[retrorod]

Thanks, Rod! I am rather fond of it. AFAIK, It's the only Banner Gibson ever inspected twice. For the book project, I tracked down the original 1943 flattop inspector and asked her to reinspect my guitar. It passed, again:

 

She looks like she has only seen light usage, jt! Again....Gorgious! Cool story about finding the original inspector

Noticing the unbound fingerboard. Can you tell me which year Gibson added the binding to the fingerboard?

What a great era for Gibson acoustics! I would love to get a hold of a J35...

[jt]

She looks like she has only seen light usage, jt! Again....Gorgious! Cool story about finding the original inspector

Noticing the unbound fingerboard. Can you tell me which year Gibson added the binding to the fingerboard?

What a great era for Gibson acoustics! I would love to get a hold of a J35...

 

Thanks, Rod! The SJ got fingerboard binding circa 1947 (about the same time that Gibson switched the fingerboard inlays from real pearl to pearloid).

 

I'm a J-35 fan, too, and which that I owned one. I've had a number stop by my home for X-rays and I've loved them all, regardless of tone bar configuration (2 or 3, scalloped or tapered).

[RASHARU]

The only problem I've found with the belly-up bridge is that you can never use a JLD Bridge Truss (if ever needed). They are fantastic little helpers but the "brass string pin" version (which is the ONLY style that may work) just looks plain silly, IMHO.