[sdiy] Build a board to restore audio

[patchell]

    This is a task that is probably best accomplished in the digital
domain.  I have not actually tried any of the programs that remove
"noises" from records, but a friend who has tried a couple told me to
save my money.  He felt that they made the recordings sound muddy.
Removing big scratches is fairly easy, however, but it is time
consuming.  I just use Cool Edit.  A scratch is generally only a couple
of samples long.  I just grab the peak and drag it back in line.

    Removing HUM is another problem.  To do this, you need a notch
filter, probably several.  Trouble is, these will introduce a lot of
phase shift around the notch.  Right at frequencies you don't want to do
this (60,120,180,240Hz).  You might be better off living with the hum.

bo ca wrote:

>   Hi to everyone!
>
> This is not about synths but maybe some of you can help me. I am
> looking for information to build a board to restore audio. Something
> to remove the noises and the typical harmonics provided by power
> supplies, records, etc...
>
> If someone could help me I will very grateful.
>
> Thank you.
>
>

--
 -Jim
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