Pre amp, signal filtering. [Archive] - Audio & Video Forums


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mosfet wrecker
01-05-2005, 02:16 PM
Have noticed many discussions on this site about microphone, phono pre amps and splitting signals or filtering out high and low frequencies. My answer D.I.Y. When it comes to pre amp several op amp I.Cs on the market will surpass any quality even the most experienced audio enthusiast will require for literaly a couple of pence. There are several simple books out there on this subject and you don't have to be a genius to understand them. If anyone is interested in a class a pre amp then there is a nice design on a website I found called (Elliot Sound Products). I myself am not attracted to class A as you run into problems with lineararity of transistors and class AB does not really eliminate crossover distortion it just moves it into to different parts of the signal. Class B is the way to go. If you fancy building your own pre amp or filter circuit then all you need is a few op amps, a soldering iron, some perf board and afew cheap components and of course a design (Very easy to find). Simple microphone pre amp, or turning a line signal into bass and treble or even bass mid and top.In some speaker systems there are three seperate speakers for the different sounds to be reproduced so instead of passive networks you could go to the extremes of tri way crossovers amd tri amping. This is probably a waste of money as the human ear can't hear what a distotion analyser can see, but who knows what the brain can percieve? Or at least you could impress your mates with your truely dedicated speaker amp and crossover network. In a nutshell if you want to split a line level signal into seperate frequencies, boost it, or want to run more than one amp with out increasing the load on the output stage of your D.V.D or what ever then a home made op amp filter or pre amp is a viable and cheap choice. Why not it will either work or it won't and it will give you something to occupy your self for a couple of hours.