Why don't acoustic guitars have adjustable saddles?

[Mandobart]

I put this one on my Eastman arch top.

[EZYPIKINS]

Archtop is whole other world.

I think the compensated nut it just that....Nuts

[mr. beaumont]

I think a well set up acoustic with a compensated saddle can play in tune well enough for 99% of the world not to hear a thing "off."

[phydaux]

Anything that adds weight to the bridge/saddle will dampen the energy that gets transferred from the vibrating string to the sound board.

[bufflehead]

Originally Posted by phydaux

Anything that adds weight to the bridge/saddle will dampen the energy that gets transferred from the vibrating string to the sound board.

Precisely. An acoustic guitar with an adjustable saddle will lose more in terms of volume and tone than it will gain in terms of better intonation.

[davidd]

Intonation is way overrated.

[FrankHudson]

I don't really know, but my guesses would be:

Tradition. A significant part of the guitar market prefers instruments that look like the classic designs.

Complication/cost. Obviously not a factor for high end instruments particularly those built to order, but it may well be that the best ways to do this aren't without "costs" (like sound, see below) or things that could disappoint a customer down the line. In the electric guitar world some bridges are subject to rattles or peculiarities in adjustment and stability that bug some users.

Change in how the sound transfers from the strings to the soundboard. This may be hard to explain, and would be better answered by someone with more knowledge than I have, but in the electric guitar world there's a mystique about things like the 3 brass barrel saddle Telecaster bridges and the one-piece wrap-around bridges such as some Les Paul Jr models have producing a desirable sound vs. "modern" 6 individually adjustable electric guitar saddle bridges.

Mentions of weight/mass seem non-material to me. There's no reason that an adjustable bridge couldn't be made be similar in weight to a regular saddle. No luthier response yet in this thread, but it's also likely that even a greater weight could be designed into the guitar's sound successfully.

I think very skilled, light touch players with good ears (those that adjust their tuning for different keys for example) would gain from this, but the simple fixed intonation bridge saddle probably is good enough for the rest of us.

[AugustWest72]

The only complaint I've ever had about my Crafter is that the saddle just does not sit properly. Every time I change strings I have to put shims underneath to get it to sit evenly. It makes for the strings to ping above the twelfth fret unless I am very careful about picking.

I love this guitar other than that. It is probably time to buy a new guitar again but all my writing and much of my progress as a guitarist has been on this guitar.

I fell in love with it despite the flaws. Typical huh.

[Alan Carruth]

phydaux wrote:
"Anything that adds weight to the bridge/saddle will dampen the energy that gets transferred from the vibrating string to the sound board."

Adding mass at the bridge doesn't really add damping, in the strictest sense. Damping refers to the losses in the system, and a heavy saddle doesn't automatically add to losses. What it does do is make it harder for the energy to get out of the string into the top, where the guitar can turn it into sound. On an electric guitar that's what you want; to keep the energy in the string where the pickup can 'hear' it, so adding mass at the bridge is generally a good thing there. On an acoustic guitar, particularly a good one, it's possible to change the sound noticeably by simply adding a few grams to the bridge, say, by swapping out the stock plastic pins for ebony or bone ones.

Trevor Gore, in his excellent books on the 'Contemporary Guitar' devotes much time (and math!) to the subject on intonation. He analyzes the causes of poor intonation (basically, the tension change as the strings are fretted), and shows how it's possible to get 'arbitrarily close' to perfect intonation by compensating the nut and saddle. Just doing the saddle won't make it. He also talks about why perfect intonation is impossible on an acoustic guitar.

Even if you get it perfect, you're still dealing with the deficiencies of 12-Tone Equal Temperament. All temperaments are compromises, and all have problems that are just built in. We tend to get used to them, but once you notice them they never go away.

[Jengstrom]

What hasn’t been pointed out is that sound is amplified very differently between an acoustic and an electric guitar.

An acoustic guitar transmits the string vibration into the top via the saddle/bridge assembly. The more efficiently you can do that, the clearer and louder the sound will be because it is mostly the vibrating top that produces the guitar’s volume and tone. Transmitting string vibration into the top efficiently is why it is so important to have a smooth, square bottom on the saddle and why it is so common for sound to improve when the (very slightly) compliant undersaddle pickup is removed. The guitar top acts as a speaker. (And as we all know, body geometry and different materials can taylor tone by accentuating or damping various frequencies.)

With electrics, the string vibration is detected by a magnetic pickup. As the string vibrates, it moves back and forth, closer and further away from the pickup. This induces a magnetic variation which, in turn, creates an output which goes to an amp. (OK, electrical engineers, I tried to keep it simple.) The top of an electric guitar is not what produces the sound (although it can be somewhat influenced by it, as in a semi hollow). Because the sound it not transduced mechanically, you can use an acoustically inefficient adjustable saddle without sonic penalty.

John