Science Behind Round/Flat String Sound?

The rounds have these big "bumps" sticking up and whizzing around quickly create more high-order harmonics than the smooth flats (which "catch" and move less air). High order harmonics = more treble content = brighter. Or, the rounds experience more air resistance and lose energy (slightly) more quickly, that excess energy loss from the vibrating string shows up as more high order harmonics in the generated sound waves (or induced electrical signal via the pickups).

 

(Or, if you don't believe air resistance has that much influence, how about the rounds have more mass further away from the center of the string, taking more energy to vibrate, more angular momentum and all that math, but to essentially the same effect - more of the energy lost faster in higher frequency overtones.)

 

Calling flats 'dead' is so 2008.

I believe rounds sound brighter because the round windings create tiny explosions with every note because they vibrate faster than the speed of sound. With flats, you don't notice it as much.

 

you want science?


flatwounds =

roundwounds =

 

Probably has something to do with mass. Might not.

 

Not really. You can have a roundwound string and flatwound string of the same gauge and mass, and they'll sound hugely different.

 

I think it has to do with flexibility. The windings on flats butt right up to one another, making it more difficult to wiggle. Is “wiggle” a sciency word?

 

It’s the relationship between mass and frequency.

Simple Harmonic Motion

 

Yes, there is science as to why rounds sound different. Flat wounds have a a lot of surface area where the winding contacts the core - that makes the string "stiff" and dispersive - the speed of wave propagation is dependent on frequency, which means the overtones are not harmonics of the fundamental. Rounds only contact the core along a line (a spiral, actually) - much less surface area in contact. The means the string is more flexible - the restoring force is more due to tension than it is string stiffness, which means the overtones are closer to true harmonics. Also, the lessened friction due to less contact area means the harmonics last longer. Pressure wounds have a contact area in between rounds and flats, so they're sonically also in between.

 

Flats, dead? Not so much. Just ask Steve Harris.

 

Yes but, ‘sciency’ is not!

 

Can you?

It seems to me that with a round wound and a flat wound string of the same gauge, the masses would necessarily be different (the flat would always be more massive).

 

magic, dark magic, witches and lots of eye of newt

 

Of course you can. I just pulled these off of our tension chart, and there's a 1.1lb difference in mass. I'm pretty sure I could have those things dead even, if I wanted.

Precision Flats FB45 - 41.5lb
Round Core Bass Boomers RC-DYB45 - 42.6lb

Nope, not always. Across the board, our Precision Flats is one of the least massive 45 gauge string we have (you can check my work on the tension guide found here).

 

Probably has something to do with construction. Might not.

 

You take a flat and a round with the same "exterior" dimensions, i.e. same width, and the round will obviously have much more metal "missing." The only way to equalize mass would be by using different materials, i.e. a less dense material on the flats and/or a more dense material on the rounds. I was assuming the same material as a given as well when I made my statement.

 

Not as much as you'd think. The flat wire used is incredibly thin (thickness), so nearly all flatwound bass strings are built up from round cover wire with a flat final cover over the top.

And that also depends on the round cover wire being used. Using a first cover of .005 is going to have less metal "missing" than if you started with a .008. The former is also going to result in a stiffer string as well, since more of that metal is grabbing onto the core.

That said, it would be incredibly interesting to make a flatwound string using only flat wire, or grinding the penultimate cover smooth and then lay the flat wire on top of it. However, my guess is that either of those would be incredibly stiff.

Other options to equalize mass would be to change the core wire diameter, any of the diameters of the materials underneath, etc.. There are a bunch of options that can result in two strings having the same diameter/mass, but different tonalities.

 

It's all to do with magnetic discombobulation




...just don't ask me how or why

 

Serious answer: a lot of it has to do with flexibility.

Roundwounds have a center core that's under tension, and the core is surrounded by a round ribbon. If you were to take the string in cross-section, you would see that the wrap is basically circular. Circles are smooth, and so they can roll against each other pretty smoothly. Imagine you take a bunch of ball bearings and put them on a string tight against each other, and then try to bend that string. It will flex fairly easily. When you pluck the string, the wrap moves with the string, allowing the energy you put into the string to make it vibrate. This lets the string vibrate at the fundamental as well as the overtones, giving you a bright sound.

Flatwounds, on the other hand, have rectangular cross-sections. Imagine now that you have a bunch of metal cubes right up against each other on that string and you try to bend it. These rectangles don't roll very easily, so when you pluck the string and the core begins to vibrate, the wrap inhibits those upper harmonics. This makes the tone seem much stronger in the fundamental and lower harmonics.