I have to replace some scratchy potentiometers used as volume potentiometers in a Rocktron Velocity 300 guitar power amp from the early 1990's.

These two parts are labelled:

  • 15A100K 9252
  • TØB10K 9303

Does someone have some informations about them or a source where I can get information?

Edit: I've found schematics for the Velocity 300:

enter image description here enter image description here

  • \$\begingroup\$ Sometimes the markings can be a bit different, but if you look at the following related question first is probably a 100K logarithmic and second is probably a 10K linear (but you'll see the codes have changed over time) electronics.stackexchange.com/questions/75840/… \$\endgroup\$
    – PeterJ
    Commented Sep 20, 2014 at 14:44
  • \$\begingroup\$ Hi PeterJ, this is a possible answer. I've found schematics containing a 10K linear pot an a 100K pot, which defaults most probably to be logarithmic. \$\endgroup\$
    – softmonaut
    Commented Sep 20, 2014 at 16:35
  • \$\begingroup\$ As the B in the 10k one means 'linear', the A in the 100k one means 'Audio' i.e. 'logarithmic'. See here for markings. \$\endgroup\$
    – user207421
    Commented Sep 23, 2014 at 7:46

1 Answer 1


A-scale pots are "audio" scale, which is sort-of logarithmic. That's your 100k pot.

B-scale pots are linear, i.e. uniform track width. That's your 10k pot.

See this reference on pots including markings.

The arrows on the schematic tell you which way they're physically oriented; I think the arrow indicates motion of the wiper with clockwise rotation but am not sure about that.


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