It's definitely worth playing with a function generator (can probably find an online/java or downloadable one for free without too much searching - I have hardware versions on the bench) if you suffer from the delusion that 2000 Hz is not treble. Blah, bah, midrange blah if all you've ever done is read stereo magazines. Actually listening will tell a different tale. And it's very worthwhile to track where your hearing cuts off, as it will drop with time and exposure - I'm down around 12Khz now...
Find a standard piano keyboard. The B&C (B6/C7) that are not hard up on the right edge are either side of 2000 Hz if the thing is in tune. The plinky C (C8) right at the high end is 4186 hz....
Or - The highest note on a 24-fret 4 string bass is 391 Hz....
24 fret 6 string bass - 523 Hz
24 fret 6-string guitar - 1318 Hz.
(yes there are overtones, and indeed, the tone control is mostly about changing how much of those you hear, but you won't notice much, if any effect from slapping a 10KHz lowpass on a bass guitar, IMHO.)
Edit - look, I was right. Easy to find one (the first one I found, there might be "better" ones out there...)http://onlinetonegenerator.com
Ohms * Farads = Seconds
1/Seconds = Hz
330KOhm*2.2nF = 726 microseconds = 1377Hz
or depending what you are looking for/at, 219 Hz for 1/(2*pi*RC) (cutoff frequency)
Or possibly 2190 if you read something wrong by a factor of 10 - the picture is missing, so I can't try to read it myself.