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Permalink Reply by Fomhorach on September 26, 2016 at 1:00am

Floating bridges have less sustain especially when doubled with an unbraced soundboard of a box. The reason being that the energy from the strings is used to create sound. So the energy disapates faster than with a solid body (it's a lot more complicated than this but that's a simple way of thinking about it).

A solid body (this would include attaching a hard tail directly to the neck underneath the soundboard) will increase sustain and greatly help with keeping tuning consistent. The trade off is in acoustic volume.

Something else to think about is that a floating ridge will allow for more changes to the instrument after it is built. You can even throw it away and build another bridge altogether. You might prefer a heavier bridge to increase sustain or switch to a lightweight one to increase acoustic volume. A floating bridge offers a lot more options.

Personally I prefer a floating lightweight bridge to create a semi-accoustic because sustain is less important to me than flexibility.  I also design my bridge last as it makes setup easier and i can  finalise design. 

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Permalink Reply by Kigar on September 29, 2016 at 3:28pm

This is interesting stuff.  So mass creates sustain at the expense of volume?

Why does a fixed bridge help with tuning?

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Permalink Reply by Fomhorach on September 29, 2016 at 4:11pm

Not sure about mass and volume but a lightweight and dense material like bone or hard plastics transmit the vibrations better and don't inhibit the soundboard (well that's the way I think about it)

Sustain is best achieved by limiting the vibrations of the string moving into something else (like a soundboard) it simply stays in the string with the energy having nowhere to go it vibrates for longer. Sustain would probably be fantastic if the string was encased in a solid iron block. Sustain/volume has been going around and around for decades. The traditional guitar shape probably came into existence because the audiences listening to a lute being played became larger and players needed a louder instrument.
We deal with sticks and boxes, acoustic volume is a bit hit and miss but if we bypass wanting acoustic properties we can just about stretch a string over anything with a pickup and it will sound OK. The great thing about building these things is the experimentation. I've had good results and crazy unexpected results. I used a key as a bridge once and the teeth of the key vibrated on the fretboard giving it a whole new type of unexpected sound. I kept it like that because it was strange and different.

Floating bridges can move out of place and upset the intonation of the guitar. If the bridge is fixed and the intonation set correctly, then the tuning is less likely to go wrong.

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Permalink Reply by Danny B. on September 29, 2016 at 4:24pm

Thanks for all this great explanation Fomorach, everyone else too!

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Permalink Reply by Ron "Oily" Sprague on September 29, 2016 at 6:03pm

Les Paul experimented with the concept of sustain in the original Log. He reasoned that the densest material he could get his hands on would increase sustain by keeping as much energy as possible in the vibrating string. He didn't know that strings vibrate in semi-sine wave fashion, and didn't account for frictional energy losses both internal to the string's material, as well as losses due to the interaction of the string with the surrounding air; but he got himself a heavy pine plank, and was able to show that it could sustain longer than the existing guitars of the time. Remember too that he attached a pickup to that Log, amplifying the longer vibration time of that string, so we could appreciate it better, and slapped the two sides of a split-down-the-middle Epiphone hollowbody to the Log, to give it dual resonating chambers, and make it look less weird, just in case.

Others have made guitars out of titanium, and they reportedly have sustain that makes the Log sound, well, primitive.

Dense bridge material means better transmission of string vibration to the soundboard, causing it to flex like a speaker, pushing air inside the box. That's why an Uncle Crow or dulcimer neck attachment style works.

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Permalink Reply by JL on September 30, 2016 at 3:57am

Here's an easy "mythbusters mini experiment" to try at home.  Zip-tie one end of a slinky to your deck rail, or similar fixed object, stretch it out and give it a pluck.  Watch the wave race back and forth from end to end.

Now connect the other end of the slinky to the middle of your shower curtain, drapes, tip of a fishing pole in a holder, rope climb on the swingset, or other thing that will move easily.  Stretch out the slinkey and pluck it again, watch the wave lose a lot of energy when it bounces off the other end.

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Permalink Reply by Cause the Blue rat on September 26, 2016 at 11:44pm

A hardtail does require a secure fit to the box. Because it's also holding the tension of the strings. 

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Permalink Reply by Danny B. on September 30, 2016 at 12:54am

This from the internet. In my mind this builder who is seemingly meticulous enough has come back to the conclusion that a bolt works pretty well. ;)

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Permalink Reply by Fomhorach on September 30, 2016 at 1:02pm

True. 

That switch would do my nut in though.

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Permalink Reply by Fomhorach on September 30, 2016 at 1:09pm

Thinking about this.. It seems like a very pretty and well built thing but .. The switch is kinda in the way of a good strum and having the bridge so close to the edge of the box is a bit dodgy. Humbucker are very heavy too and might dampen the soundboard.

If I was to guess then I would say it is more of an electric than acoustic guitar. 

On saying that, it looks great and I wish I had made it.

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