New bridge made a huge difference

[Dennis Duross]

I fit my second archtop with an adjustable bridge (abr-1 and a wenge base), after being dissatisfied with the sound of a completely wood bridge. The sound quality became much better---more articulate, better sustain---but a touch metallic sounding.

But I've always had tuning stability issues with this guitar. I couldn't get it to stay in tune for any length of time.

I don't think it was string slippage at the tuning post, as I lock the string under the windings when I restring. Not the tuners (Grover Sta-tites). Not the adjustable part of the bridge, as the abr-1 was as low as it could go and was resting directly on the base.

Anyway, I made a new, nonadjustable bridge (white oak base, bone saddle) and set it up last night. Not only does it sound great, the tuning problems are gone.

Does anyone have an explanation?

I'm including a before and after shot below.

[Mark Swanson]

A wood and bone bridge will always make a big difference in tone as compared to a bridge with that much metal in it. That's a given, the ABR-1 is quite massive. As to tuning, who knows- but you replaced the bridge and it was better, so that to me points to some instability somewhere in that metal bridge.

[Dennis Duross]

Yes, that's the only thing I can figure too, although how exactly the abr-1 was contributing to the problem is beyond me.

In any event, the wood/bone bridge has a warmer tone than the abr-1 did, so there's a plus as well.

[Dave Stewart]

Dennis, fwiw I put a non-adjustable rosewood bridge with bone saddle on a current build I'm working on and was also very happy at how great it sounded. I'd avoided bone 'till now for fear it might become too treble balanced, but that didn't happen. I shaped & hollowed it some to get the weight down (27g total).

[Mark Swanson]

That's pretty Dave!
I have a little trouble with the term "non-adjustable", as these floating bridges are adjustable because they can be moved around...that actually makes them more adjustable than most! But I know what you meant.

[Dennis Duross]

Dave:

Like everything you do, that looks great. At this point mine's just a trial, so I didn't do anything fancy with it. It's just a 1/2" thick piece of white oak, 5" long by 7/8" high. The 1/2" thickness is just enough to accommodate the 4.5 degree saddle slot, but that obviously leaves a chunk of unnecessary real estate in front of the saddle on the bass side, and below the saddle on the treble side.

The curves you used solve that problem nicely.

[Craig Bumgarner]

As someone once explained to me, every piece on a guitar filters the sound to some degree. The materials and the amount of it used affects the sound. It is the choice of the builder what sounds good. I like my guitars to have a very fast attack and a quick decay and to that end, I think the lighter the better. I've been using rosewood as it is about a resonant as one can readily get and EIR is about the lightest of the rosewoods. The bridge pictured below is a pretty standard Selmer style bridge. Though some very successful builders of this kind of guitar and bridge use a saddle, I don't as all wood is more traditional and I like the more primary connection between the strings and the bridge. The bridge is hollowed out on the sides and from the under side, they usually weigh ~ 11 grams (w/o the little mustache pieces on the sides).

bridge.jpg (68.05 KiB) Viewed 18219 times

bridge 2.jpg (67.98 KiB) Viewed 18219 times

[Beate Ritzert]

Nice bridge. That is basically a two feet bridge, not a full contact bridge, isn't it?

Which brings me to a typical amateur's question: are there any plans/rules for the compensation (angle) between saddle line and the base of the bridge?

[Michael Lewis]

Beate, there are no rules, but many people like the base of the bridge to be perpendicular to the strings. In a design sense it may make sense but the saddle and it's relation to the strings is the only part I really concern myself with. This is the beauty of a floating bridge, it can be adjusted for intonation even if it doesn't look quite right to some folks. If your bridge base is perpendicular to the strings then the saddle where the strings contact should be angled back on the bass side about 3mm ( 1/8") more than the treble 'e' contact point.

[Beate Ritzert]

Thanks Michael.

I was always aware of the adjustability of a floating bridge. As we have some freedom to position the top of the bridge relative to the contact surface we might try to utilize this to optimize for the tone (violins, for example, react pretty sensitive on small variations of the bridge position)
Do You or someone else know about experiments on archtops?

[Michael Lewis]

Experiments? Are not most archtops an exercise in experimentation? The ones in my shop often seem to be, though I have found a reliable group of measurements to give me good results without having to make new discoveries.

What sort of information are you seeking?

[Beate Ritzert]

Simple question: wil the guitar sound "better", e.g, "fuller" if the bridge is a bit closer to the neck or a bit further to the neck. A bit means the amount of roughly 1 cm we have to shift the position of the top line relative to the foot. And how might (!!!) that depend on the bracing (my archtops both have V-bracing).

[Michael Lewis]

It seems to me there are enough variable elements in a guitar that one can not draw a simple answer. I suggest you try moving your bridge and listening to the open strings as the fretted strings would all be out of tune.

For a fuller sound I think the guitar body should be not too stiff or heavy, as those qualities seem to damp or choke the response. Conversely a guitar that is too thin and light can easily be over driven and will often sound muddy. The trick is to find the 'ball park' between stiff and flexible and stay near there. So many things effect the sound: selection of materials, arching profiles, graduations, gauge of strings, weight of bridge, string break angle at bridge, mass and stiffness of neck, size and placement of sound holes, scale length, overall string length, tailpiece length and maybe mass. These and more elements interact to make the individual voice of the guitar, and if you change one item it may well effect others in the way they all work together.

[Alan Carruth]

Compensation:
The best treatment I've seen on that is in the Gore/Gilet books. It gets pretty technical, but when you get done you understand why and how compensation works, and can find out how to set it up for a given set of strings and length. To be really right, you need to compensate the nut as well as the saddle, sometimes by more than you might think.

"Simple question: will the guitar sound "better", e.g, "fuller" if the bridge is a bit closer to the neck or a bit further to the neck."
When I was learning to make violins I was taught that the 'proper' place for the bridge was at the highest point of the arch, or, to put in more correctly, the proper place for the high point was the bridge location. The point is to design the arch to work with the string length you've chosen.

One big variable in the tone equation on archtops is the tailpiece. In particular, how close it is to the bridge, and the pitch(es) of it's vibration modes, can affect the way the guitar sounds. The most important mode of the tailpiece is the one where it flaps up and down relative to the top, hinging around the saddle/hinge at the lower edge. You can see that this would push on the top, and if the pitch of the tailpiece is close to that of one of the top resonant modes the effect on the sound can be quite noticeable. The closer the bridge is to the tailpiece, the more strongly the 'top' and 'tailpiece' resonant modes will be coupled, s moving the bridge around changes that relationship, as well as the way the bridge works with the top. We usually think in terms of altering the tailpiece geometry itself, but since it's the relationship that counts here you can get the same result (more or less) from either end.

The bottom line is that there are very few _independent_ variables on the guitar, and that makes it hard to figure out what any one change will do. It does keep things interesting!

Alan Carruth / Luthier

[Ed Gerber]

Alan,

Thanks for your comments on the importance of the tailpiece. I understand that the break angle from the tailpiece to the bridge plays and important role in the sound, but I hadn't considered the up and down movement of the tailpiece(although now it certainly makes sense!). Do you think that an unmoveable tailpiece has an advantage or disadvantage over a moveable one? I have built archtops with moveable tailpieces and I also built a bandolim with a rigid tailpiece. The bandolim sounds good but could improve. I'm wondering if changing to a moveable tailpiece would help?

Thanks,
Ed

[Alan Carruth]

It's always hard to say how a change will affect things. The more information you have about things like resonant frequencies the better able you'll be to figure that out. Not knowing that stuff about your guitar, and what you consider 'better', I can't say from here. And, BTW, I'd bet that 'non moving' tailpiece still moves.

Alan Carruth / Luthier

[Ben Loutrelle]

Dennis,

I have a similar solution for the bridge of my archtop; bone saddle over hardwood bridge. It is only a hypothesis, but after observation of both the saddle and nut in refining the action setup, I noticed indentations at both the bridge and saddle that seem to indicate the windings of the string had remained stationary, while the core was stretching to tune. It seems that when the wound strings are unable to slide at their contact points they keep the string length stable. I have observed that though the wound strings are much more stable, the plain B and E are relatively variable. I will also say that the setup process with this bridge/saddle combo required a sort of 'settling in' period, but once adjusted, remains in tune far longer than any other guitar I have played. I have dropped in down stairs, in a case, and it still played in tune. I also believe that this type of assembly also allows the bridge to rotate slightly on a perpendicular axis to body. This seems to be due to the imperfections inherent in my design for a floating saddle at the bridge. Where an ABR bridge's resistance to moment deflection forces a string length change, and therefore produces tuning instability, this inadvertent flexibility produces not only a livelier instrument, but better a better playing one. I believe either of these hypotheses may be supported by the innovative Evertune bridge, and in the use of locking nuts and bridges on instruments designed for more 'aggressive' musical expression. Musical may also need to be in quotes.

[Dennis Duross]

I just swapped out the white oak base pictured above with spruce. Same shape and dimensions. 11g in weight, and it is again a noticeable improvement. Not sure what the negatives would be w/respect to using spruce, but for now I'm liking the difference.

[Mario Proulx]

Define "improvement"?

For example, did it get brighter? Or did it get more bass?

Just saying it improved doesn't tell us much if we don't know what you are wanting/needing as an improvement....

[Dennis Duross]

That IS a pretty lame descriptor I guess, but I don't know as any other term I might use would be any better. I sort of lack the proper vocabulary (and experience), and that doesn't help.

By comparison, the sound was a bit more muted before---almost like the tone control on an electric had been dialed down somewhat before, and now it's been dialed up a click or so. And louder, seems to ring a little longer too.

That's no better, is it?

I'm not trying to achieve some particular sound here---I'm just swapping out components to try and see what changes occur. I've made two guitars that have the same specs, and have been changing bridge bases and necks, and comparing the sound. Not scientifically, obviously.

Right now, the only difference between the two is that one has a maple neck and the other has a narra neck.

Anyway.