Installing Audio Filter in receive audio stage?

[Onelasttime]

Thinking about trying this. I am thinking that doing an 800hz low pass with 1200hz corner/notch filter might greatly enhance listening pleasure. Also thinking about using bipolar caps in place of some of the receive audio circuit to filter/dampen the high freq.'s. Normally this area of a radio is full of ceramic disk caps and sure they will last forever they also are harsh sounding and let everything pass right on through.


I was thinking about maybe an audio transformer but then I looked at the cost and said no way! I also want it to be separate from transmit audio processing so I am not having to switch on tx and rx.

What do you guys think of this idea. This is for mobile application so no space for rack gear and no desire for anything I need to adjust constantly really looking for a passive solution.

Anyone do this or try it? What parts did you use and what freq. range did you find best? I am trying to do this just in the audio stages it is not a matter of receive band width. Of course the louder you turn up the audio in a mobile situation the worse it get's!

 

[loosecannon]

You said low pass filter, which would mean that everything above 800hz would be attenuated.

My guess is that you meant to say "800hz high pass" filter, with a notch at 1200hz in order to dip that particular freq. Is that correct?

not sure about how to incorporate the notch filter, but you can change cap values in the receive audio chain in order to get the audio response you are looking for.

also, ceramic disc caps will tailor audio frequencies just like any other form of capacitor.
not sure what you meant by "let everything pass right on through".
No, they are not the best type of cap to use for audio paths, but for a two way radio, they are just fine IMO.

I have a line out jack on my base station that feeds into a 10 band EQ and then into a stereo receiver.
I can tailor the audio in my radio in any way i want, and i am glad to have the ability to change it on the fly, as there are so many different types of stations out there.

I personally would find a small mobile type EQ and send line level to it from the radio.

If you want to experiment with component changes inside the radio, i might be able to tell you a few places to start. just let me know what kind of radio it is.

LC