8-Track hiss reduction attempt ..

Audacity Help Forum GNU/Linux
1

I am currently digitising 8-track cassettes and although some of the later machines had Dolby B mine certainly do not.
Therefore out of interest not so much because I feel it is necessary I am trying to play around with Audacity to see if I could reduce tape hiss effectively without it altering the overall sound of the music in a way that would be audible.

Seems a combination of filter curve being pulled down to -6 dB added to noise reduction on a small section of tape hiss at the start of the recording then extended to the entire recording seems to do the trick…

Can people think of a better way to do this ? and also why what I have just described here may not be a good idea if it is not.

I digitise a lot of cassettes VHS cassettes 8-track cassettes etc and never use Dolby when it is available (I think of it as a muffler; the rationale being if you do not abide tape hiss use CDs); I was just interested in seeing if it could be created give or take using Audacity regular modification customisation settings

Thanks for constructive information
noise reduction.png
filter curve.png

2

That flat EQ is the same as amplify by -6dB.
IMO better to experiment with bass & treble as the track is playing, than use that flat EQ.
Hiss is most intrusive at the high end of the spectrum. (i.e. try cutting treble).

3

Thanx
So all I did with first bit was to lower amplification :wink:
Many articles I read went in your direction ie bass treble to lower the highs ok cool

4

My preferred settings for Noise Reduction are 6,6,6 (as recommended by Forum elf Koz)

I used it recently to remove FM carrier hiss, with very good results, on a BBCradio broadcast that a folkie friend of mine was on.

Peter.

5

Dolby is the best thing to start with, if the tapes are recorded with Dolby.

Then Noise reduction in Audacity. But this is tricky because you can get artifacts (side effects), especially if the noise is bad, and “the cure can be worse than the disease”. It’s just something you have to experiment with to see if you can make an improvement. Sometimes it’s best to use noise reduction during the fade-in and fade-out. And of course you can completely silence the gaps between songs.

Lowering the level makes the noise lower but it also makes the signal lower so you’ll just end-up turning-up the playback volume and you’re back where you started.

Bass & treble is really up to you. If you have a “bad recording” with no highs then reducing the highs can reduce the hiss without affecting anything else. But that’s rare so you usually end-up reducing the highs and you have to decide if you prefer it “dull sounding” with less hiss or if you prefer keeping the highs and living with the hiss.

and never use Dolby when it is available (I think of it as a muffler;

If the tape is recorded and played-back with Dolby the frequency response isn’t affected. But, since many cassettes, and many cassette players & recorders, don’t have good frequency response it was pretty common to turn the Dolby off during playback.

Dolby works by compressing the dynamics of the highs during recording… Moment-to-moment weak highs are boosted, but strong highs are not boosted (so strong highs don’t saturate-distort the tape). When you play-back the highs are expanded… Again strong highs are not affected but the now slightly-boosted weak highs are reduced back to normal. The hiss (which is also weak) gets reduced too,

6

yes yes and yes

“the cure can be worse than the disease” :wink:

i guess there is no total cure/fix it is just a case of playing around to get what sounds ok; but thanx to all here will carry on tooling around with it all …

7

i shall try that

EDIT: tried 8/10/8 that is good too it really does take away most of the hiss … but truth is the original full sound is still better overall … as I said just trying all this out