WD Music archtop bridge?

[Avery Roberts]

Here's another factor to consider. An arch as a structural element is very strong when presented with a distributed load. On the other hand it is quite weak and flabby when presented with a point load - that's because the sides of the arch tend to "bow out" on either side of the point load.

Now a two foot bridge presents two of those point loads so that's better than a single point load but the arch is still weak. But a solid bridge presents a distributed load to the arch so the arch is very strong.

How this translates to the tone of the guitar is a difficult question because the vibration patterns of a guitar top are quite complex. But I think it can be deduced that with a strong arch such as you would have with a solid bridge, the top would vibrate more like a large piston and should have better bass response. This seems to be so because in my case with the two foot bridge the guitar had very little bass response, but the bass response improved considerably with the solid bridge. As did the sustain as well - the guitar acquired a nice "singing" quality to it. I note that the forum member with the Ibanez AF55 reported that the tone was more "substantial" with the solid bridge. That probably was because of the increased bass response.

Cheers and I hope this helps - Avery Roberts

[Little Jay]

Here's another factor to consider. An arch as a structural element is very strong when presented with a distributed load. On the other hand it is quite weak and flabby when presented with a point load - that's because the sides of the arch tend to "bow out" on either side of the point load.

Now a two foot bridge presents two of those point loads so that's better than a single point load but the arch is still weak. But a solid bridge presents a distributed load to the arch so the arch is very strong.

How this translates to the tone of the guitar is a difficult question because the vibration patterns of a guitar top are quite complex. But I think it can be deduced that with a strong arch such as you would have with a solid bridge, the top would vibrate more like a large piston and should have better bass response. This seems to be so because in my case with the two foot bridge the guitar had very little bass response, but the bass response improved considerably with the solid bridge. As did the sustain as well - the guitar acquired a nice "singing" quality to it. I note that the forum member with the Ibanez AF55 reported that the tone was more "substantial" with the solid bridge. That probably was because of the increased bass response.

Cheers and I hope this helps - Avery Roberts

With the solid foot base at least I am sure the downwards force of the strings is fully being collected by the tone bars without warping the arch of the top. I feel the solid foot can’t deform the arch and I think a two foot bridge can, especially if the feet are not seated directly over the tone bars.

And yes, bass response has improved, not necessarily with more bass, but with tighter and more defined bas. I suspect because of a better/more direct transfer of the string-energy.

Funny enough, the sound and response feel more solid with a solid foot bridge… what’s in a name?

[JohanAbrandt]

I think that one problem with a solid base is that if it is badly fitted or if the wood changed with age or season, it can create several points of contact not necessarily in an optimal placement, and the bridge rocks or tilts.

The two footed bridge minimizes this and there is also less wood to fit to the top. In addition the two foot bridge follows the slight deflection of the top under tension easier.

But a perfectly fitted solid base is my preference as well

[RJVB]

In one of the bridge fitting videos, possibly the StewMac one, the luthier explains he removes a tiny bit from the centre of the base so as to deform the top very slightly, "load it" in his terms. I don't know if there's any actual sense to that, but the solid maple bridge on my old German archtop seemed to be made like that. But that one had a single transverse tonebar (more or less) under the bridge.

Pinned bridges: they're very different animals with a different mechanism of transfer of vibration to the top. Probably more effecient: the pull on the string anchor point is also transferred. The only archtops I know of that use one are Daniel Slaman's The Dome nylon-string archtops in one of their versions (you can see/hear one on daddystovetop's YT channel). But they were in use already on guitars from the early 19th century, possibly earlier.

Saddle slots: my tech removed some material around the low E saddle slot in an attempt to remove a buzz, and since then I have to be careful how I play the string in order to get a proper ff or else it gets plucked right out of the slot. I guess that the risk when your luthier works mostly with clients who play amplified, with pick or with pin/tie bridges where slots are pointless. I'm going to have to make a tiny shim to heighten the treble side of the slot until I get a new saddle installed. The treble slots are a bit too deep to my taste though, I've already played with the idea to redo them with the CA glue + bone dust or bicarbonate trick used for nuts (if that's going to be hard enough to behave like a tiny bone insert). Maybe if the original saddle fits on the posts of the new base.

[sgosnell]

You can get buzzes from the saddle slot if the slot is too wide and too deep, just as you can from nut slots. Refilling a slot with cyanoacrylate, with or without an additive, is one way to fix it. Smoothness is more important than hardness here, I believe, because the wooden saddle isn't that hard in the first place, and cyano is generally at least as hard as ebony, even without additives, unlike the usual nut, although ebony and other woods have been used for nuts. Most people seem to believe that harder is better for nuts, but I'm not certain that's always the case for every guitar.

I think our definitions of 'pinned bridges' differ. On archtops, pinned bridges refer to floating bridges which have the posts going all the way through the bottom of the base, and into matching holes in the top, 'pinning' them into place. Reading the post above, I suspect the pinned bridge mentioned there refers to standard flat-top bridges, with pins to hold the strings in place. There is little relation between the two.

With a floating bridge, pinned or not, there are too many factors in play, and the interactions are too complex, for me to make an a priori prediction about sound differences between a solid and two-footed base. My experiences are all over the place, and far too limited to be valid. I just try what I have available and see if I like the tone of the replacement better, or worse. This applies to both solid carved and to laminate tops. More bass is not always better, and with bigger archtops less is often better. But quality is as important as quantity. If I don't like the sound of an archtop, I may swap out multiple bridges trying to improve it. It's entirely trial and error, because I can't accurately predict the outcome in advance. Perhaps some more experienced luthiers can, but I can't.

[RJVB]

Sorry for the pin vs. pinned bridge confusion. You did say pinned, and I was a bit surprised that it'd be necessary to go into the difference between a floating and a standard flattop bridge here...

The assumption of a malformed, deep 6th string slot was indeed what prompted the sanding down of the saddle top. It helped somewhat but there's still some buzzing going on that we haven't been able to trace to any of the usual culprits, but it could be related to the saddle lean.

Interestingly just about all (biscuit cone) resonators I've seen have quite deep saddle slots. They also have a more or less floating bridge (relative to the guitar body), but break angles are probably typically less than on an archtop AND they tend to be played with a good amount of digging in too. The lower slots on my reso saddle are deeper than the string diameter, and that doesn't cause any issue despite the lower tension of the nylon strings I use. The only string that can cause some buzz is the G, and that one isn't so deep but probably just too wide depending on the individual string (not rectified) and/or its age (stretch causing thinning).