Ampeg SVT-2 Pro midrange selector control not working

[spikemacgee]

I have an Ampeg SVT-2 Pro from about 2000 or 2001 and the midrange selector control (five position knob) does not appear to be working. I also have an SVT-3 Pro which essentially has the same preamp and the selector on that makes a pretty big difference. On the SVT-2 Pro I hear no difference in the sound between selections whatsoever.

I'm wondering if it's a defective switch or could I be lucky and it's just a little dirty? I don't have the schematics but even if I did I'm not smart enough to read them

I'm going to carefully take it apart and check things out but any tips you might have are appreciated.

Thanks.

 

[anderbass]

When my SVT-II's mid tone knob is nearly centered, I dont notice any difference between my mid frequency positions either.
Just as a quick test, try pegging your mid tone knob to 10, and then see if your "midrange selector control" becomes more responsive.

 

[Warpeg]

You wouldn't be able to notice a difference in the frequency selection when your mid +/- knob is in the middle. When it's in the middle it is set flat, which is to say that it is not boosting or cutting the selected frequency. This is also known as a semi-parametric midrange EQ.