Originally Posted by sodas
It seems treble knob is not doing anything at all on my bg250...
I own an active instrument with fresh strings and a passive one and i get no change at all .
Worst thing about it is i bought this from an English online store and i live in Greece so even if i send it back to get a replacement i `ll have to live without amplification for a month .
The treble control has a lot to do with what goes into the tweeter and the crossover frequency for it is quite high. The changes in tonality as far as what's coming through the 15" are very subtle and it's designed that way.
It's not just selecting a center frequency and boosting it from 0 to 10. Center point is 12 o'clock (zero on the control plate) and it's cutting that frequency range in steps @ 1-5 below that. With the treble past 12 o'clock it's increasing a different and higher frequency range in steps @ 1-5. The spillover highs above that should end up directed to the tweeter.
It's not gonna react like other treble boosts. You won't hear as much change when you increase treble as you would with a linear control based on just one frequency. I don't get that with mine either so it's possible yours is working fine but you can try this to make sure the tweeter is functioning OK.
Cut the bass and mids then turn master volume on the amp and treble up all the way. Put your ear in front of the tweeter and you should hear a higher pitched hiss if it's working as it should. You can also run some recorded music through the aux. input and listen in the same way. You should be able to hear the music through the tweeter. Block the 15" off with a pillow if you have to so you're hearing most of it through just the tweeter.
If it passes both of those tests then the treble control is working the way it's designed to. If you have any concerns that I haven't addressed contact tc electronic customer support. I asked them the same questions you're asking here. They got back to me within 24 hours and I'm passing their answers on to you. Best of luck to you.