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Re: noise reduction-parametric eq. RFI

Subject: Re: noise reduction-parametric eq. RFI
From: Walter Knapp <>
Date: Wed, 01 Dec 2004 20:07:49 -0500
From: Syd Curtis <>

>
>
> John Hartog (Mon, 29 Nov 2004 21:38:45 -0000) described how he went about
> reducing unwanted noise using a parametric equaliser function of Cubasis
> VST.  Even I could follow his explanation, and I'm very non-technical.
> Thanks John.
>
> That encourages me to try a bit harder to use the program I've got, which=
 is
> Waves Q10.  It has what I take to be an excellent parametric equaliser.

The Q10 used to be near the top of the heap. Some of the newer stuff is
more capable now, but it still will do a excellent job.

> However, right now I have a problem which I suspect is not amenable to th=
e
> procedures John has described, and maybe there is no solution, but I'd be
> grateful for advice from this so-expert group ... even if only to confirm
> that there's no fix.
>
> A friend has some analogue audio cassettes of his father reminiscing abou=
t
> his experiences as a radio operator on ships early last century.
> Fascinating material, but unfortunately the tapes were made with the
> recording level way too high, and severe distortion has resulted in some =
of
> it being unintelligible.
>
> There's some background noise which I can probably deal with.  And if I
> can't, my good friend, Vicki Powys, has offered to help.  But is there
> anything that can be done about the overload distortion?
>
> I would be extremely reluctant to take these unique tapes away from my
> friend's residence, and therefore I have copied one by playing it on my S=
ony
> Walkman WM-DC cassette recorder and taking the line-out to a Tascam DAT
> recorder.  The Walkman in play-back mode shows the recorded level of the
> signal and this often went over +5 dB, which is why I fee reasonably
> confident the problem is overload.
>
> Any advice would be welcome.

If all else fails, what I've done on really valuable material is expand
the sound display out to where the individual samples are visible, then,
using the pencil tool carefully redraw the waveform for the clipped
areas. This has all been digital clipping, which is pretty obvious stuff
at this level, don't know how well it would do with a copy like this
where the sound problems won't be so obvious in the waveform.

In any case it's extremely tedious work, even if only dealing with a few
seconds. Only a last resort, but I've had really good results once I
figured out how to draw it. You have to save new files frequently as
it's easy to mess up and have to backtrack.

You might want to try several different cassette units for the playback,
some may do better than others. Instead of overrecorded, some of the
problems may be head alignment.

Fiddle with every filtering method you have on it, some may help. Often
this sort of thing is frequency dependent, so don't give up on the
equalizer without trying it. Limiting the frequency range to voice range
may help a fair amount.

Walt




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