Cause of frequency offset

[Diamondj421]

I have a "rare" Velvet Boost EQ by a company called Audinc. Its basically a stereo EQ with a low frequency band and high frequency band on each channel. When using Waves Q Clone, I noticed that the right channel was fine but the left channel's bell curves were not centered on the proper frequencies. Everything was shifted down about 200Hz. I've been trying to fix it. I've switched out IC's to see if one had failed but saw no change. What would cause the frequencies to drop like this on an EQ? Unfortunately, I'm not the first owner and had never used Q Clone on it before so I don't know how long it's been like this.

 

[Monte McGuire]

The specific values of the frequency determining components (R, L, and C) will cause this to happen. The amplifiers cannot affect this. If you need them to be accurate, then you have to get a pile of components and select pairs/quads that have the same value.

Not sure what kind of EQ circuit this is, but for a typical analog EQ, specific components determine these frequencies, and you can control it by controlling the value of the parts you put into the circuit.

 

[Diamondj421]

Thank you so much. So if the frequencies are still spaced apart like they should be, just lower, there’s probably a capacitor early in the circuit that would be causing the offset? Here’s a picture of the unit.  I know it won’t provide much help but maybe you could get a general idea of what I’m workin with.

 

[Diamondj421]

Also, please excuse my ignorance here, but how would I go about finding the bad capacitor in the circuit. Everything I've ever built or worked on has had instructions on what to set my DMM to, where to place the probes, etc. I'm very eager to learn more about this though so I can fix/understand the circuitry of other preassembled units.