As I am familiar with some synthesizers, I often user real life circular sliders (e.g. to control the master volume), also called knobs. Like this one: frequency controller on radio

Sometimes I also find these controls in virtual applications (yes I like extreme minimalism =P): a simple circular slider

But most of them are irritating, confusing or just wrong, and simple sliders could be used instead, making the UI much better. What are the advantages of circular sliders like the one in the screenshot above? And when do you use them? Thanks

+1  A: 

Circular sliders will gain popularity as multitouch technology improves and users can actually "twist" the knobs with two fingers. I'd be interested if anyone has seen a well designed circular slider for an ipad app.

In my opinion, circular sliders don't have a place in mouse-driven UIs unless you are explicitly trying to make something look like its real life counterpart (i.e. training and simulation software).

+1  A: 

IMHO, never. I can't really think of any real advantage besides that you're imitating a control people are familiar with from the real world. And I don't buy that this is worth the disadvantages you named.

+1  A: 

When it controls the rotation of something. Of course, one must then make sure that the direction it points in is also the direction of the controlled object.

(I'm not familiar with this actual technology, so please ignore this answer if the knob can't actually be rotated 360 degrees)

Oh and they're handy when space is limited.

Bart van Heukelom
+1  A: 

Propellerhead Reason uses them extensivly and does a good job of it.

alt text

The trick is to make the value go up and down when the user moves the mouse up and down (or maybe left to right) - almost like a slider. Never try to make the value depend on the mouse cursor angle!

Numeric tool tips also help.

As for good usage scenarios: If you need lots of adjustable values (like in a synthesizer) in limited UI space.

Andrew Russell
I personally prefer left and right
Bart van Heukelom
If the operation to rotate a knob is to move the mouse up and down (or left and right) then weight is lent to the argument that knobs are a poor choice in mouse-driven interfaces. What you call a knob is in fact a slider coupled with a picture of a knob.
High Performance Mark
I doubt an up-down rule would be intuitive; IMHO for a knob to be intuitive, up-is-increase when the mouse is on the left of the knob and down-is-increase when the mouse is on the right of the know. In short, clockwise/counterclockwise is the relevant bit, rather than up/down or left/right. I agree though, that making the knobs dependent on mouse cursor angle would be a UI nightmare.
Lie Ryan
Lie Ryan: That would be terrible! Instead of one grab region that did one thing, you'd have two **smaller** clickable regions, right next to each other, with no visual difference, that did two completely different things!
Andrew Russell
+1  A: 

hmm, i remember some music software used those knobs, but i guess first of all they used them because they look same like on mixers.

I think the only other reason could be that it saves Space!

you need a square instead of a line that would be longer..

+1  A: 

They don't take up much room, so many of them can be added to mixer controls etc.

Positions like 90 degrees left, right, or straight up are easy to see at a glance.


If you're already committed to abandoning the primary advantage of a software-based user interface over a hardware-based one (i.e. the ability to easily resize and rearrange control elements), just so that your program looks like a piece of rack-mounted audio hardware, then you might as well use knobs.

After all, they're no worse than the tiny little toggle switches, or the fake LED displays that can only show one item at a time.