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Hi Dan,
Thanks for uploading the unprocessed audio sample. That really helps. Your
azimuth alignment seems pretty good. There's a
bit of azimuth wander but that's to be expected with a slow speed
microcassette track.
Automatic solutions are not ideal. The best approach is to identify each
particular type of unwanted noise in
the recording and then attempt to remove each of them, one at a time, with a
dedicated tool.
So with that in mind...
1. Hum.
There's a mild hum with a fundamental of around 149 Hz and a total of four
or maybe five harmonics above that. Probably caused by the cassette
recorder's motor
and transport. I was able to greatly remove them with my Acon DeHum tool.
With similar settings you should be able to do the same in RX Dehum.
2. Random noise.
Unfortunately the hum is not the main issue. As you mentioned there's a lot
of
random noise, and worse of all, right in the critical voice band. That is
the worst
kind to remove, often impossible. My approach is always to filter out
everything below the
lowest recorded speech frequency, and above the highest. In this case I low
pass filtered at about 300
Hz, and high pass filtered at about 3000Hz, both with a Q of about 5.
It gave a mild improvement in listenability without degrading the wanted
voice.
Your Corrective EQ tool sounds like the equivalent tool in RX.
3.Clipping.
I hear some sort of ugly distortion on voice peaks. Its
spectrum goes up to at least 10kHz. I doubt it's on the
microcassette tape. Possibly when you transferred, the playback volume on
the GE was too high and
it was clipping its internal amplifier. Try lowering the GE's playback
volume to where the clipping stops. But dont go too low as there may be a
low level noise from the GE's amplifier (the hum?) which you want the tape's
own
content to mask. Somewhere in the middle is usually the best.
You might try RX's Declipping tool but as mentioned I would first check the
distortion isnt caused by the playback/recording chain.
4. I didnt attempt to use a Denoiser/Dialogue Denoiser and that was
intentional.
Hope this helps Dan,
Tim Gillett
Perth,
Western Australia
----- Original Message -----
From: "Dan Gediman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, June 22, 2018 11:42 PM
Subject: Re: [ARSCLIST] Processing micro cassette audio using iZotope RX5
Thanks, everyone for all your input so far. Some info that might help
clarify things. The unit I’m using is a GE micro cassette tape
player/record, NOT a mini cassette. Second, removing the tape and
transferring it to a standard cassette is not an option here, as I have to
return these tapes as is to their owner. Lastly, the unit has a mono
mini-plug earphone jack and the recording itself is mono. And I’ve already
adjusted the azimuth to the best of my ability using my ear. I don’t have
access to a meter to check precisely (unless someone can suggest a software
meter that would work).
As far as RX5, I have used the De-noise module in spectral mode, feeding it
a sample of the background noise. It has made it substantially better, but I’m
trying to see if I can make it ever better. I also experimented with the
presents of the corrective EQ module. I haven’t tried the Spectral Repair
option, because frankly I’m not sure how to use it properly. If you think it
could help, I’ll go online and find some tutorial videos to bring me up to
speed. Ditto for any of the other RX5 modules that you think might help
(de-clipping has been suggested, as has de-reverb).
Since I assume most of you have upgraded to RX6, here are the available
tools in my version of RX5:
De-clip
De-click
De-hum
De-noise
Spectral Repair
De-reverb
Gain
Corrective EQ
Channel Ops
Resample
Dither
Someone asked if I could upload an audio sample. I’m not sure how to do that
in a listserv, so I have uploaded a raw, unprocessed sample to Google Drive
here: https://drive.google.com/open?id=1NuYkyKK6yNXzDRtOA_ZUHuYzf6VCAwuK
<https://drive.google.com/open?id=1NuYkyKK6yNXzDRtOA_ZUHuYzf6VCAwuK>.
Anything else you think I should try, hearing the file and knowing what I
have already tried?
Thanks again!
Dan
Dan Gediman
502 299-2565
[log in to unmask]
www.dangediman.com <http://www.dangediman.com/>
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