Sounds like thoses certain songs are "overloading" the input circuit of the equalizer. Some of the Audio Control's I have seen have an input level control, or a switch on the back for "low" and "high" gain. If you have either, try turning it down. Also, an important thing to keep in mind with equalizers is: it is the SHAPE of the curve that matters, not WHERE the curve is. ie., if you like a smiley face curve, that smiley face could be all above "0", centered on 0, or all below 0, and it will do the same thing. The point is that if the curve is all above Zero, then you are amplifying the signal with your eq, which is BAD. It is always better to CUT some frequencies, than boosting the other frequencies. So if the curve is all below Zero, then you are cutting some frequencies. You would then simply turn up your preamplifier volume control to compensate. The distortion your describe is almost definitely due to overloading circuits. The trick will be to figure out if it is the input of the eq or the output of the eq that is overloading.
Help? Equalizer Question
I have an Audio Control C-101 Equalizer which I sometimes use with my system. It is run the the tape loop on the preamp. When playing certain songs on CD's it causes bad distortion. If I turn the equalizer off the distortion is gone. This doesn,t happen at random. Every time I play that particular song using the equalizer it is distorted. I have checked conections I dont know how many times to be sure it is connected properly. (Could it be bad cables?) Any feedback on this, besides don't use the equalizer, would be greatly appreciated.