Plugins for cleaning up audio files

Some of my early compositions are on cassettes. Unfortunately the individual parts are gone. After transferring them to audio they sound bad. Is there a plugin that would help me clean them up? I’ve tried using the various plugins in Cubase 12.


This is audio restoration task. You have much more options and tools in WaveLab for this.

iZotope RX is pretty much industry standard for noise removal and repair.

Thanks for your reply, I’ll check it out.

Have you used Izotope Elements? I’m curious if the version that cost 40$ would be helpful.

Perhaps you could qualify what you mean exactly by “sounds bad” before shelling out money?
Is it high noise levels? Lots of options there for noise reduction, as mentioned RX, Wavelab, Acon Digital Acoustic, all those have demo version, so you wouldn’t necessarily need to spend money to test them. Maybe even the free Audacity could work.
Is it distorted? That will be a lot more difficult or even impossible to fix properly, although you could give it a go with iZotope declip.
Is it wobbly? Now you’re into real trouble :wink: the only program i am aware of that can repair tape wow and flutter is Melodyne Capstan, and you don’t want to look at the price of that…

Could you perhaps upload a 30-second clip somewhere, so we could hear what needs to be repaired?

Great idea, I’ll find a good representation and upload it today, or tomorrow.

An entry level version of SpectraLayers is included with Cubase 12 Pro

I’ve attached a simple example (not dense) of the sound quality.
I’m just learning audio engineering, so I really appreciate your time. My gig has always been a musician / songwriter.

On my system, it sounds less like the track needs noise cleanup, but just something that would be more akin to mastering?

The idea is to minimize the need for restoration in the first place by ensuring that the initial transfer from cassette is optimal. What I hear is:

  • a lack of high frequencies (muffled sound)
  • stereo imbalance (louder on the left channel)
  • tape flutter

The more serious of these is tape flutter (rapid tape speed fluctuations, perceived as pitch fluctuations), however this, and both of the other issues, might be due to issues with the cassette player used for the digitzation.

While it is possible that the tape flutter is on the original cassette (caused by the device used to create the recording) I’m going to guess that the more likely source of the problem is the tape player that was used for the transfer, simply because when the recording was made, cassette machines were current, and thus more likely to be in better condition.

In 2023, a typical cassette player will be 30-40 years old, have a build-up of tape oxide on the heads (explaining the muffled sound and stereo imbalance) as well as on the pinch roller and capstan (possibly explaining the flutter), the heads and capstan may also need to be demagnetized, and the machine may have aging drive belts which could contribute to speed fluctuations.

So before we even look into analysis of the clip, could you provide some insight into how the digitization was carried out? If you’ve done this yourself and have the cassette player, there are some simple cassette machine maintenance steps that might help, or it might just be a matter of finding a better machine,

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lol - these days, there are plugins to add the analog charm of tape flutter to pristine modern recordings.

But you’re right - if the tape flutter is considered undesirable, that would be restoration, not just mastering.

Great info and questions, thanks!
The cassette deck is a Tascam 130. I cleaned and demag’d the heads using a cassette cleaner by “Roadshow”. I’m not sure if it cleaned the heads or not. There wasn’t any discernable difference. Perhaps I should use something else?
The 130 has a setting for Dolby noise deduction B or C. I marked a couple of the tapes stating that I used Dolby B. So when transferring those tapes I set the cassette deck to “B” .
The first go around, I connected the RCA outs to the 1/4" inputs on audio interface (Steinberg UR816C), then recorded while the cassette was playing.
The second time I connected the RCA outs to a digital recorder. I then used the Sd card from the digital recorder and imported the audio from the SD card.
Thanks again, I look forward to your suggestions.

The specs of the Tascam 130 certainly suggest that the flutter should be more or less inaudible, so let’s hope that the problem wasn’t with the recording machine and therefore on the tape itself. Assuming the cassette is not damaged, the only other thing I can think of is to spool it fully in both directions a couple of times to ensure a uniform wind on the spools. Stop me if you already know all of this!

Personally I find the best way to clean tape heads is with a little isopropyl alcohol (propanol) and some cotton buds. To do that, you need to be able to get access to the heads – I’m not familiar with the 130, but it might be possible to eject the cassette bay, and just lift the outside cover off to expose the heads. If not, then there are extra-long cotton buds available which would reach in from the top of the open cassette bay.

The procedure is basically to use (very) little isopropyl alchohol on the cotton bud to gently wipe the surface until no more dirt comes off. This is usually brown and the same colour as the tape. Use multiple cotton buds until one completely clean, then allow to air dry completely.

The capstan and the pinch roller also need to be thoroughly cleaned. A build-up of tape oxide on these could lead to slipping which could result in tape speed fluctuations.

I use a demagnetiser that looks like this:
Just keep your cassettes well out of range while using one of these!

I would also recommend doing a transfer with noise reduction switched off. This might be the only way to recover some of the high frequencies. The decoding can always be done if necessary using e.g. the Anaxwaves DDi Codec.

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Thanks for sharing your wealth of knowledge, you rock MrSound man! I’m going to clean the heads with isopropyl as suggested then transfer the tape again. In Cubase 12 I’ll boost certain frequencies as needed in C12.
I’ll upload the clip again for comparison.

Cool Cubase stock plugins you may wish to try for relatively quick results include:

Yeah, looking forward to it! Those three plugins will really help.
As MrSoundman suggested I’m transferring the cassettes again with Dolby NR off first, then I’ll get into them.

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