Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Audio filter . . . . kinda

Status
Not open for further replies.

jstacy

New Member
Ok I have a question and I am hoping someone here can answer it. I am trying to filter audio but not really!? Ok let me explain

What I am trying to do is more like leveling the volume of audio. So basically I want to pull the peaks out without degrading the actual volume. So the volume would stay the same just some of the louder parts of the audio output spikes causing that section of audio to be louder than the rest.

So what I was hoping to do is to build something that will filter the peaks out on the fly so that all I have to do is pipe audio in and the audio that comes out will have the peaks filtered out without removing that section of sound. Also I am not trying to have a set volume as the volume I may pipe into this could be louder or softer but still has these peaks. So I was thinking that maybe I could build into my little project a way for this to be dynamic to the volume that I am feeding in. (maybe I am just trying to make it to complex)

Is there something out there that does this already or is this something I can build fairly easily and quickly also is there some documentation that will point me in the right direction.

Thanks for any help you guys can give on this.
 

schmitt trigger

Well-Known Member
Most Helpful Member
If I understand your post correctly, you are looking for an audio compressor.
Audio compressors, in the good old analog component days, were designed with either JFets acting as voltage controlled resistors or better yet with voltage controlled amplifier's (VCAs).
Nowdays it is all performed in the digital domain.
The attack and release times for these contraptions was crucial to prevent the audio from "breathing".

Google voltage controlled amplifiers.
 

Blueteeth

Well-Known Member
Depending on the quality and requirements (instrument? microphone? bandwidth of signal...) you could use a simple compressor circuit used for guitars. Perhaps not ideal for your app (guitars don't have much bandwidth), but its a start. There are also VCA's, as schmitt mentioned, which perform a similar function, altohugh these are usually used in voice applications, such as audio conferencing...whereby speakers may move around, closer and further form the mic, so the circuit varies the gain in order to keep a relatively constant volume. Of course when someone stops speaking the circuit shouldn't ramp up the gain to max, then you'll just hear noise getting louder (the 'breathing' thing).

Yet another wonderful acronym to help you out is 'AGC', amplitude gain control. This guy's circuit is pretty good and I used it for skype...I hate wearing headsets:

Microphone AGC amplifier
 

jstacy

New Member
Thanks

This is all really good stuff thanks guys you have been a huge help. I will dig through everything and find something that I can build on the cheep and easy.

Thanks!
 

ke5frf

New Member
I was thinking it sounded more like a graphic equallizer circuit he was looking for, but I suppose that would be rather obvious.
 
Status
Not open for further replies.

Latest threads

Top