[quote name='HowieBass' timestamp='1471676153' post='3114894']
I've got the Spectrum LX which has the same EQ options (except on mine the Volume is a push pull pot for In Phase/Out of Phase). The Active Tone should do nothing until you engage it using the Active On/Off toggle switch, at which point clockwise rotation from centre position should boost treble (which seems to offer a fixed boost as you sweep through a range of frequencies) and counter-clockwise rotation from centre position should boost bass (again it sounds like this is across a range of frequencies). The centre position of the active tone is not flat, there's definitely a change in character as soon as you engage the active tone. On mine, the other mini toggle switch is a coil tap which offers a sound closer to a single coil instead of a humbucker, though my bass is a P/J pickup configuration. My bass has an 18v circuit and if the Thunder II is the same you need to check that both batteries are supplying power correctly before consigning the active EQ to the dustbin (eg. there could be a problem with one of the battery clips).
EDIT: Here's a circuit diagram for the electronics:
[url="http://www.westone.info/wiring/thunder2abass/index.html"]http://www.westone.i...bass/index.html[/url]
[/quote]Many thanks for posting. Righto then. Multimeter on, hyperdrive engaged....