Mandolin bridges

[northfolk]

What is the difference in a standard adjustable bridge vs. a full contact base adjustable bridge? I have an Eastman 815 and want to upgrade the bridge with a Cumberland Acoustics; of which there are many variations; full contact base, standard base, etc? What configuration is best for an F style mandolin? Thanks, Gary

[Eric F.]

Hmmm. I think your question might get more responses in the "Equipment" area. The newer Eastmans come with good bridges, but assuming you have an older one or just really want a Cumberland Acoustic bridge. ... I don't see any options on the CA Web site other than color of the thumb wheels and having it slotted by them. That said, I think you're probably just being confused by marketing copy. You want your bridge to make "full contact" with the top of the mandolin. Put another way, you want no air space between the bridge base and the top plate. But you - or someone - will have to sand the bridge until it fits perfectly once you have it. And it doesn't matter if you have an A or an F. Just be sure you know whether your fretboard is radiused.

Ah, Fretbear's response makes me understand what you're talking about. D'oh!

[Fretbear]

Not easily answered or agreed upon. I use the full-foot version that Steve makes and couldn't be happier with it. They are not too widely used, as they are mostly a special order item, and commercially sold ones are usually the two-footed variety. Sam Bush has always had his bases sanded down to remove the void, and that must have a different effect than leaving the full base mass. Mike Compton reports having had good luck with both types. I like the idea of fully driving the top, and feel that it does give an edge in regard to volume and presence.

[Tighthead]

There are other options on the CA site: low boy saddle, high boy saddle, a choice of two radiused saddles, etc.

I'm pretty sure the "full contact base" option on the CA bridge means the bridge base doesn't have that little arch in the middle.

[Rick Lindstrom]

Even if you don't intend to build a bridge of your own, you can learn about the differences in foot contact if you visit and read Red Henry's maple bridge page:

http://www.murphymethod.com/redbridge.html

For what it's worth, I just made one of the 11 hole basic bridges for a mandolin of mine and am really happy with the result.

Rick

[northfolk]

Thanks for the feedback. In my mind, more is better? Most of the non-adjustable bridges are full contact bases; the aluminum topped adjustable bridge on my 1921 Gibson A2 is a full contact base as well. CA does offer this base as an option and I was not sure if it is suitable for my mando. Thanks, Gary

[Rick Lindstrom]

If you read the "What Gibson left undone section" at Red's site, it'll shed some light on your question.

Rick

[Paul Hostetter]

To me the two main criteria for a well-functioning bridge are 1) the base making complete contact and 2) being sufficiently compensated to play in tune. Materials are much less important.

This is a "full foot" Gibson bridge, photo provided by Gibson in their own ads. You'll notice the end of the bridge has lifted right off the top, which (I hate to say it) is everything wrong with bridge fitting on one succinct image.



The notches for the strings are nothing to rave about either.

When a bridge actually fits the top, you can really hear the difference. It's worth getting it right.

Every off-the-shelf bridge I have ever encountered, including Cumberland bridges (which I heartily endorse and use in my shop) don't really fit the top without some effort. But you can have the best bridge in the world and if it's not fitted well, you don't have much. I am very fond of Gibson's old one-piece bridges too, like this:



I've seen the Red Henry ones and quite a few others. If they play in tune and they fit the top, that's most of the battle. The Brekke bridges aren't wide enough to allow for good compensation. The Gibson above is barely wide enough.

I think people often try a new bridge and mistake details like the wood it's made of for more important "after" issues such as how well the base fits, slight changes in playability, or even the sound of new strings.

[sunburst]

I'll put a word in for the "two foot" style of bridge base (the type with the raised center so that you have two bridge feet (sort of like a violin bridge) rather than the "full contact" type).

When a mandolin is exposed to higher or lower relative humidity, the arch of the top changes shape. If the bridge base is one piece and fairly stiff, the fit between the bridge and the top changes. (That could be what happened with the Gibson example in Paul's picture, though that one is pretty extreme.)
I like to carve the raised section in the center of the bridge base thinner than it is normally manufactured so that it becomes more flexible. If the top changes shape with changes in humidity, the bridge base can flex a little and the fit can remain better between the bridge feet and the top.

BTW, the older Gibson one piece bridges are much shorter than the common Loar style bridges, so the fit doesn't suffer nearly as much from changes in top shape.

...and another thing. If a mandolin has problems with the top sinking under the bridge feet, changing to a "full contact" base is a good remedy.

[Stephen Perry]

With enough height on the base, pretty easy to determine whether a mandolin likes full contact or not. Fit to full contact. Then relieve the middle and see if there's a change. I tend to like a fairly wide air gap zone. But the parts contacting must really contact!

[Paul Hostetter]

I think the Gibson with the full-contact foot was fitted to the top at rest, or fitted to their CNC top arch template, and once the top was under load it went flat and the bridge couldn't follow. But it's pretty typical of how so many bridges on mandolins look: close, but no cigar. I agree that ideally a two-foot bridge will breath better from season to season, but there are so many variables to consider.