Shim under bone saddle: defeats the purpose?

[Alan Carruth]

SteveS wrote:
"Would be a bit of an understatement to say that final agreement on how sound is generated and how best to make a top is a distance of?"

What's curious is that, so far as I know, _nobody_ in the physics community disputes this: most of them don't even think about the tension change signal. It's only guitar makers that believe this. I can understand why they do, to some extent, but I'm a bit puzzled as to why the belief is so widespread, and so tenaciously held.

"Certainly, archtop guitars are primarily driven by transverse motion. The thought of a rocking or even forward/backward drive being fundamental is nonsensical with a tail piece and non-fixed bridge. Clearly, the primary, if not the only drive for these instruments is transverse.
[snip]
So, how’s that for a guess?"

Could be better....

At any rate, that does not address the question I asked: why don't archtop guitars sound an octave lower in pitch that flat tops with the same strings? Given the differences in driving mechanism that you're proposing, that's what _should_ happen. Why doesn't it? It's not just because the archtop is not very effective at producing lows: those tones are not simply 'weak', they're not _there_.


Anyway, as Charles Tauber said, archtops don't generally use ladder bracing. They sound the way they do for a whole lot of reasons that have nothing much to do with the way the string drives the top, and everything to do with the box itself. The arch adds a lot of stiffness to the top, without adding a lot of weight, so the top has very high 'impedance' (it's hard to move) in the low frequency range. That stiffness means that the main 'tap tone' of the top is fairly high in pitch, as compared with most flat-top guitars, and that, too, favors treble. Add to that the fact that the 'main air' resonant pitch on most f-hole archtops tends to be up around A or even a little higher, whereas on flat tops it's usually around G, or lower on big ones. This means there's much less reinforcement for the fundamentals of the lowest notes on an archtop. It's quite possible to get strong bass from an archtop, it's just not the way they're usually made, and not what the players are usually looking for. I've built a couple of archtop _classical_ guitars that sound a little 'lute like', but are perfectly acceptible for playing the usual classical repertoire.

Speaking of tailpiece guitars, have you heard any recordings of Leadbelly playing his Stella 12-string? That one had a tailpiece _and_ ladder bracing, and it sure does not lack for bass!

[sjspinner]

One quick question.
In making a shim for an existing bone saddle on a 12 string that has a UST underneath it, would you make the shim out of ebony or bone?

Of course it would be best to get a new saddle, but let's assume that is nor possible at this time.

So? Ebony or bone shim for a bone saddle with a UST underneath?

Thanks

[studiodunn]

Originally Posted by walternewton

If the shim is done correctly, I doubt there's much, if any, discernable difference - but I'd hope that anyone passing themself off as a pro would have enough pride in their work to start over and get the job done right (saddle blanks are cheap).

This is It IMO.

[sjspinner]

Originally Posted by studiodunn

This is It IMO.

So you say there should be no difference using bone or ebony as a shim against a bone shim? Wouldn't bone be preferred especially having a transducer under the saddle?

[budsy]

The guy advertises he is a Luthier then he should do the job right

without the need for shims under the saddle

Id ask him to do the job all over again, and if not then you should tell

other guitarists his name etc so they pass around he isnt up to the job

But give him the chance to rectify the job without the need for a shim
under the saddle and this means starting again with a new saddle inserted .

One of the best shim materials I've used with bone, TUSG or plastic saddle?

Saddle lengths of guitar strings (usually an A).

Theoretically all wrong, but something so right.

But with a UST? The guitar is already "shimmed."

This thread...new saddle.

Or a Rare Earth soundhole pick up.

[sjspinner]

Originally Posted by Fret Buzz

One of the best shim materials I've used with bone, TUSG or plastic saddle?

Saddle lengths of guitar strings (usually an A).

Theoretically all wrong, but something so right.

But with a UST? The guitar is already "shimmed."

This thread...new saddle.

Or a Rare Earth soundhole pick up.

So with a bone saddle and a UST underneath, would you go with an ebony or shim made of bone?

[mseso]

Honestly, I read only the question and didn't read the answers. I know answers will be different. But I know I wouldn't be satisfied with job and I would ask him to put new bone saddle. I would even be unhappy and angry. When he would do to me, I would never again go to this man.

The reasons are:
- people are talking this and that, but nobody really knows what will be with sound - so better safe than sorry and worry
- I didn't ask him wood I only asked him bone
- on some my guitars I changed saddle and it is not a big deal. I bought comensated type saddle for that guitar and it was very easy to sand mainly at the bottom. You can't sand too much if you are not careless or in a hurry. If you go with slow steps (which IS SLOWER !!!) than there is no mistake you can't correct with barely noticeable neck reset)

[sjspinner]

Let me rephrase my question.

I lowered the bone saddle on my Guild 12 string too much. It buzzes some now.
I have a under the saddle transducer also.

So my question is whether you would go with an ebony or shim made of bone to raise the height of the saddle?

Thank you

[Dwight]

Originally Posted by sjspinner

So my question is whether you would go with an ebony or shim made of bone to raise the height of the saddle?

I would go with ebony because that's what I have available. Either would be fine. What matters is that it's done accurately.

[mc1]

i recently had a new saddle installed by a very famous luthier and it was shimmed at the bottom. i was surprised but i'm convinced he knows what he is doing.

[sjspinner]

Thank you for your responses.

[Rbutton]

Originally Posted by drive-south

I think you are forgetting that no piece of material will ever be perfectly flat. So you have multiple surfaces that are contacting each other, and neither piece is perfectly flat so there are voids between the 2 surfaces. So there are voids between the saddle and the top of the shim, and voids between the bottom of the shim and the top of the bridge slot. Those voids add up. If there are 2 layers of shim, there are voids between each layer. In my opinion, this is a situation we all should avoid.

Consider the irony of paying in excess of $100 for a FWI saddle blank, then ending up with shims under it. It does defeat the purpose of carefully selecting material, making sure the saddle is properly shaped. Any shim is a red herring that really doesn't belong there.

This is exactly correct. I have added Ebony to shim bone but I run the mating surfaces exactly flat using a end mill cutter on a Bridgeport. Then I super glue the surfaces together with pressure. I can glue ebony to bone or bone to bone but butch surfaces must be exactly flat. You can’t get this with a flat block and sandpaper. You may ask why I just don’t start over? Well I put a lot of time into gettting the intonation as close as I can. Not just a “B” bump and call it good. There is a fine line between perfect string height for each player and that string height will change as the guitar changes with seasons. Done correctly, you will need er notice a shim be it it bone or ebony.

[Mr Fingers]

Some world-class luthiers have posted on this forum saying that a decent shim has no sonic downside. I respectfully disagree. It is quite possible that a thin shim may usually have no immediate audible consequence, but that still doesn't make it a good practice. AS another post mentions, where sound is concerned you really don't want to have it transmitted through layers of differing materials unless you want to change what you hear. I think of a shim as something you can often get away with, but I don't maintain my instruments to that lowered standard. May as well go for the micarta saddle, plastic pins, plastic nut... My opinion is that it all adds up and so you should never cut corners. But maybe I'm just obsessive.

[justonwo]

I needed higher action on my Schoenberg. I fussed about getting a new saddle but in the end Howard Klepper sent me a nice little kit of ebony shims. I laid one into the saddle slot - no glue. I didn’t hear one iota of difference in the sound. I think if the surfaces mate reasonably well it’s not a big deal. But if someone were making a new saddle for me, I would want the height right without a shim.

I hope this will help the OP, though perhaps 7 years too late.