archtop bridges -- flush vs. floating

[EvilTwin]

Is there a tonal advantage here?

 

On most archtops I see, I see the "floating"-type bridge with the far sides touching the top, with the middle portion not touching at all (I've heard it said that the top can vibrate just a little more this way).

 

However, on a few archtops, I have seen "flush" bridges, and I own a Cordoba Gitano gypsy jazz guitar which has a bridge flush to the top.

 

It makes sense to me to have a flush bridge (more energy to transfer to the top), but all gypsy jazz boxes I've seen besides the Cordoba's do NOT have them.

 

I love the sound of my guitar, but I'm wondering if I can get more out of it by replacing the bridge.

[Pascal]

The floating bridge is part of the original Selmer/Maccaferri design. that's why all Selmer copies tend to use it too.

Regarding its effetc on tone, here is what I found:

 

"The primary movement of a floating bridge under string tension is vertical, with very little torque or rock, which is why the tone is mid-range dominant. The wide, glued on bridge of a flat-top guitar is driving the soundboard in a more complex way that favors fuller overtone development. The amount of down-pressure on the bridge greatly affects both tone and volume. Greater load favors the fundamental pitch and more volume, while lesser load makes for a richer tone with more harmonic overtones but somewhat less volume.[...] Bridges on these guitars are hollowed out to reduce mass and increase volume."

 

Read the whole page

[mikeSF]

there are several schools of thought on archtop and violin bridge design, and perhaps as many variables between two non-identical guitars to prevent any really good comparison which would solve the mystery once and for all.

I know in his books and videos, Benedetto favors the smallest mass bridge which is still structurally sound. i have been lucky enough to have three of his guitars to examine closely and though they all had the "flush" bridge base, 2 of the 3 had the wood drilled away from underneath to reduce mass. Seems to be a trick of the trade. On one of his videos, Bob suggests that although he typically makes the "flush"-contact base, the two footed one may in fact be acousticall superior because the two transference points are directly above the braces where they matter most; what is in between is not nearly as important.

 

There is also the D'Aquisto school which incorporates a massive bridge base that is wider on the bass side than the treble(like the Kasha classical guitars). All I can say is that i had this bridge on a guitar which i replaced with a less massive one and saw an amazing difference in the amount of liveliness in the top. that big footprint was killing much of the low frequencies and a great deal of the total volume.

 

i have a Palen with the two foot base and it is the most lively top i own. Of course, there are far too many variables to conclude anything from that besides the face that the 2-foot design does not seem to hinder any transferrence.

 

obviously, it is best to experiment on your own guitar and see if a change has a positive or negative effect on the sound.

[EvilTwin]

Originally posted by Pascal The floating bridge is part of the original Selmer/Maccaferri design. that's why all Selmer copies tend to use it too. Regarding its effetc on tone, here is what I found: "The primary movement of a floating bridge under string tension is vertical, with very little torque or rock, which is why the tone is mid-range dominant. The wide, glued on bridge of a flat-top guitar is driving the soundboard in a more complex way that favors fuller overtone development. The amount of down-pressure on the bridge greatly affects both tone and volume. Greater load favors the fundamental pitch and more volume, while lesser load makes for a richer tone with more harmonic overtones but somewhat less volume.[...] Bridges on these guitars are hollowed out to reduce mass and increase volume." Read the whole page

 

Hmm...thanks for the link. That's interesting...but kinda confusing, too. First he says a wide, glued-on bridge (like on a flat-top), favors fuller overtone development.

 

Then he says the opposite -- a floating bridge giving less load makes a richer tone.

 

I guess on the Selmer-style guitars, though, since there's so much tension on the top already, it could be excessive to have a flush bridge.

 

I kinda wonder about the thinking elsewhere in that article, though. X-bracing a Selmer type guitar would be like ladder-bracing a new D-28...it just doesn't make sense to do it.

 

You buy the Selmer for the more percussive tone you get from ladder-bracing, and you buy the Martin for the bassy boom with the highs and mids floating within it that X-bracing provides on a big guitar.

 

At least that's what I think...

 

Originally posted by mikeSF there are several schools of thought on archtop and violin bridge design, and perhaps as many variables between two non-identical guitars to prevent any really good comparison which would solve the mystery once and for all. I know in his books and videos, Benedetto favors the smallest mass bridge which is still structurally sound. i have been lucky enough to have three of his guitars to examine closely and though they all had the "flush" bridge base, 2 of the 3 had the wood drilled away from underneath to reduce mass. Seems to be a trick of the trade. On one of his videos, Bob suggests that although he typically makes the "flush"-contact base, the two footed one may in fact be acousticall superior because the two transference points are directly above the braces where they matter most; what is in between is not nearly as important. There is also the D'Aquisto school which incorporates a massive bridge base that is wider on the bass side than the treble(like the Kasha classical guitars). All I can say is that i had this bridge on a guitar which i replaced with a less massive one and saw an amazing difference in the amount of liveliness in the top. that big footprint was killing much of the low frequencies and a great deal of the total volume. i have a Palen with the two foot base and it is the most lively top i own. Of course, there are far too many variables to conclude anything from that besides the face that the 2-foot design does not seem to hinder any transferrence. obviously, it is best to experiment on your own guitar and see if a change has a positive or negative effect on the sound.

 

I will definitely experiment on my Cordoba. They glued the darn bridge down, though, so it's gonna be a little extra work.

 

I'm very interested to see what a two-footed bridge will sound like. Right now the thing is tremendously loud with, of course, a lot of treble and high midrange focus. With a different bridge, though, maybe there'll be a little extra resonance and bass. It does have a ton of fundamental, even for a Selmer-style guitar.

[mikeSF]

violins typically use the 2-foot design made out of hard maple. there must be something to that.

[EvilTwin]

Originally posted by mikeSF violins typically use the 2-foot design made out of hard maple. there must be something to that.

 

I guess so, even though it runs counter-productive to what, to me, seems logical...more driving the top equalling better sound.

 

BTW, amazing instruments in your sig.

[mikeSF]

Originally posted by EvilTwin I guess so, even though it runs counter-productive to what, to me, seems logical...more driving the top equalling better sound. BTW, amazing instruments in your sig.

 

well, another way to think about that is more logical is to consider a spruce soundboard of a piano, same exact concept as a guitar, carved into an arch with bracing and a string rests on a wooden bridge, etc. have someone hold a note or chord and you apply thumb pressure in different areas on the vibrating board. you can dampen entire areas of the board and greatly influence the tone just based on the "footprint" of your fingers/hand and the degree of downward force.

A luthier friend(not Bob B) used the term "pumping" and says a smaller bridge allows the top to "pump" more air. he also believes the more downbearing(from the strings), the more that soundboard gets stifled, as it is possible to negatively impact your tone be using string that are too heavy.

[EvilTwin]

 

Originally posted by mikeSF well, another way to think about that is more logical is to consider a spruce soundboard of a piano, same exact concept as a guitar, carved into an arch with bracing and a string rests on a wooden bridge, etc. have someone hold a note or chord and you apply thumb pressure in different areas on the vibrating board. you can dampen entire areas of the board and greatly influence the tone just based on the "footprint" of your fingers/hand and the degree of downward force. A luthier friend(not Bob B) used the term "pumping" and says a smaller bridge allows the top to "pump" more air. he also believes the more downbearing(from the strings), the more that soundboard gets stifled, as it is possible to negatively impact your tone be using string that are too heavy.

 

 

Hmm, that's interesting, and a good way of putting it. I might even have to move back to .10's (I put Argentine .11's on to make the change not so drastic from my flat top with .12's).