Physical knobs are wonderful things. They can be large enough to grab with you whole hand, like a door knob, or small enough to twist between thumb and forefinger, like a radio dial. They can be textured and made with materials to improve friction. They can give tactile feedback as they are turned. They can snap into position or stop turning when they reach the end of their range. They can fit an infinite range of values into a tiny circle. They are intuitive controls that don’t even require the user to look at them as they are used.
However, knobs do not translate well to virtual UIs. All of the tactile qualities are gone, and the twisting motion that is so intuitive to those of us with opposable thumbs becomes an awkward test of hand-eye coordination in two dimensions.
And so, we find another case where Apple’s skeuomorphic designs, while visually beautiful, are less usable than they should be. The latest version of GarageBand has an impressive collection of simulated instruments, all of which provide controls for adjusting the sound. Here, for example, is the control panel for a Bass Synthesizer.
As you can see, they are all knobs. Beautifully rendered, yes, with animation that is smooth as butter, but the first time I tried to turn one, it did not behave as I expected. I grabbed the knob on one side and tried to rotate it clockwise by dragging my mouse in a circle, effectively tracing the knob with the cursor. The knob turned just a little bit, but then stopped and finally reversed directions and turning counterclockwise until I stopped moving. With a little bit of experimentation, I figured out that to turn a knob, you should move your mouse straight up and down. Up will turn it clockwise, and down will turn it counterclockwise. Moving the mouse left and right has no effect.
I wasn’t the only one to have this problem. I got to observe my lead guitarist as he used the software for the first time. He did exactly the same thing I did. He never got the up/down movement, instead discovering that he could control it by swiping up and down on his Magic Mouse (the same action you would make on a scroll wheel). This turns out to be the most elegant method of controlling them, and I’m sure it’s what Apple had in mind.
Apple went to great lengths to design these panels, customizing them for each type of instrument. There are many different styles for different types of keyboards.
Yes, that vintage clavichord has rocker switches and scratches in the finish. But how easy is it to tell whether the treble filter is on or off? Keyboards aren’t the only instruments that got special treatment. Here’s a bass guitar.
Even instruments that wouldn’t have controls on them have been given the treatment, such as this upright concert bass.
The sheen on the dark-stained wood grain of the knobs and the little notches in them are exquisitely crafted, but I can think of more informative ways to show the settings.
Yes, it’s true that a knob can fit more data in a smaller space. For example, this pan knob takes up much less space than the slider beside it.
It also gives a numeric readout while in use, which the previously mentioned controls do not. But it doesn’t seem like these panels are cramped for space.
Knobs are inherently physical controls. There are better widgets for use on screen.