Quote Originally Posted by oohms View Post
if you want to upgrade those lm324, might want to consider something like OPA4134
Actually, I am looking to replace 1 of the LM324's. Only half of it is used and I don't see the sense of wasting prime real estate on half a chip that does nothing. I'm looking at getting a single LM358 to replace it, from the documentation I've found, it looks to be a dual op amp from the same family. Can anyone confirm this? If this is the case, I've already got a NTE cross ref number for the chip that I can likely get locally, it'll give me an excuse at the very least to go back to the store where I got all the goodies I posted earlier and find out how my "ordered items" are coming along. Thinking I'll go with Digikey for future purchases as overwhelming as the site can be. They've obviously got a huge selection and decent prices from the looks of things and I can order only what I need which will also lower costs a good bit.

Quote Originally Posted by cdolphin View Post
Most of those capacitors are what actually do the filtering and amplification. I hope I am not preaching to the choir, is that of only two circuits classes.

For reference, Impedance is the frequency dependent variant of resistance, basically the point of your EQ system.

The basic setup for most EQs I have seen (I have only made one as a test for very limited frequency bands)
Involves piping the sound through a number of RC circuits with calculated impedance to match your goal EQ frequencies, then running that through an op amp with a voltage follower loop. Afterwards, the influence of this RC filter is moderated by a potentiometer (the impedance of which is simple its resistance)

I can attach a PDF of a simple lab we did last semester, it is written in very simple language and may be helpful for you to actually do, just to get an idea for what is going on.
Thank you. You've confirmed something I thought I recalled finding on the net when I started this project but have been unable to find that link again (forgot to bookmark it and don't remember the search phrase used).