"Large knobs" refers to a term commonly used to describe objects or controls that are bigger or larger than usual. It suggests that the knobs in question are relatively big in size.
Sentences with «large knobs»
Most of these puzzles come with large knobs, perfect for little hands, and some even make sounds. (breastfeedbabywearclothdiaper.com)
There are also large knobs for radio volume and tuning. (kbb.com)
The stereo's controls are simple to operate, with large knobs that are all close enough to the driver. (cnet.com)