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Bulk Digitizing Old Cassettes

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Bulk Digitizing Old Cassettes

Postby Mobileman » Tue Dec 04, 2018 7:38 pm

A dear friend gave me about 100 cassettes that she used to record her favorite college radio station show in the 80's. The show means a great deal to her and she would like to preserve them for her lifetime on CD's. The quality is horrible. I think they were recorded with a cheap boombox. They sound like they're coming from a speaker that's under several thick blankets. I know that they will never be pristine, and she doesn't expect that, but I can't give her a handful of cassettes that sound that bad.
The music is Quiet Storm type R&B of varying production quality. I need help badly for the following reason.
There are far too many tapes to try to isolate problems (Spectrograph) and one tape might have tow nights worth of programming and one show is better than the other.
I wonder if there is a plugin(s) or preset in Adobe Audition that I can set up once and then just play the tape and get a better listening quality (not pristine).
If so, what would be the settings and how do I set it up so that it is active at the input and I don't have to transfer it and then run it again in order to process it.
I hope this is clear and I hope someone can help. This dear friend just retired and spends much time alone at home while crazies run the streets. This is one instance where music means more to someone than it probably should, but then again what is music for?
Thanks
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Re: Bulk Digitizing Old Cassettes

Postby desmond » Tue Dec 04, 2018 8:49 pm

*Personally*, I would just record the cassettes to files, with no processing at all.

Applying bulk processing (once you decided on what processing to do) is so quick, easy, and reversible, so it doesn't make much sense to try to apply processing in real time as you're recording the files. (I"m not even sure Audition can apply plugins on it's input, anyway... but other software can, depending on your platform.)

You can always do a few test recordings and play with them to decide how you want to process the files, but in the meantime, your computer can be recording in the background.

I recorded probably 50+ old cassettes of mine - I just set up a cassette deck and an old computer, set the cassette deck to auto-reverse (so both sides would play) and just left the computer to record for how long the tape lasts. When I'd come back, I'd put the next tape in and kick it off again. Once I have the raw recordings, I could choose how to edit/split/process/re-output at will, without ever changing the raw recordings.
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Re: Bulk Digitizing Old Cassettes

Postby James Perrett » Tue Dec 04, 2018 8:51 pm

The secret to good cassette transfers is to tweak the playback machine for each tape so that it matches the machine that recorded the tape. Clean heads that have been demagnetised are essential - that under the bedclothes sound could simply indicate that your tape head needs a clean. Cotton buds and pure isopropyl alcohol are the best way to clean tape heads but I'd suggest keeping the alcohol away from the pinch roller as it may damage some pinch rollers.

You also need to adjust the azimuth of the tape head to match the tape - I find that the best azimuth setting is different for almost every tape. I try listening in mono to check the azimuth. If the treble disappears in mono then adjust the azimuth screw until it returns to its maximum.

Once you've set up the playback deck properly you'll probably find that you need very little processing although a little Aural Exciter (or Stillwell's Exciter JS effect in Reaper) can help to focus the treble and sharpen things up. Unfortunately there's no quick solution if you want decent cassette transfers. You may end up with a favourite processing chain but each tape will require slightly different amounts of processing.
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Re: Bulk Digitizing Old Cassettes

Postby Tim Gillett » Tue Dec 04, 2018 10:36 pm

If the recordings are in fact as muffled as you describe there's little to nothing can be done. We can boost the treble hugely but it will also hugely boost the background noise treble as well, making them uncomfortable to listen to. This is not necessarily easy, rewarding work even for those of us who do it as a paid job.

But I'd ask myself: " If these recordings were really as bad as they seem, would the person who made them have endured listening to hours upon hours of them played back?" In many cases live recordings were terrible from the moment they were made, but sometimes not. So called "direct" recordings off radio using even just a cheap boombox could sound quite reasonable, and not badly muffled.

Possibly they're better sounding than you have experienced and it's mainly a less than optimal playback that makes them sound as bad as they do. James has some good advice on playing back the recordings optimally, capturing all the information, which in the world of expert "audio restoration" is like the First Commandment.

All the best with it,
Tim.
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Re: Bulk Digitizing Old Cassettes

Postby Mike Stranks » Tue Dec 04, 2018 11:11 pm

Welcome to the forum! :thumbup:

Bulk standard processing across the board is always going to be a compromise, but you may be able to achieve something...

Check-out Izotope RX Elements. There are some good tools in there which may help. The Denoiser has an 'adaptive' setting which means it can alter parameters dynamically (to an extent) to suit the material.

I'm not familiar with Audition, but many editors/processors have a batch processing facility into which you chain various processes.

So:
* Digitise all the recordings making the adjustments that James has suggested, but don't apply any processing during the transfer.
* Set up a batch process of all the digitised files and include dynamic processing as part of the batch process.

Of course, make your digital copies of high quality - eg WAV, 24-bit, 44.1KHz - and keep that quality up throughout all subsequent processing. If you have to convert to MP3 make that the very last thing you do.
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Re: Bulk Digitizing Old Cassettes

Postby Wonks » Tue Dec 04, 2018 11:55 pm

It might be worth using a high pass filter during the basic digitisation process to cut out unwanted low frequency noise. You'd need to try it on some of the tapes to see when it starts affecting the actual music, but a 12/dB octave slope starting at 40Hz should be pretty safe and make life easier later on.

If it's recorded via a mic from a radio, then there's probably not a lot of musical info below at least 60Hz, maybe higher if it's from a really small speaker.
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Re: Bulk Digitizing Old Cassettes

Postby Sam Spoons » Wed Dec 05, 2018 12:29 am

What they said....... Make the source the best you can by setting the playback machine and record with no processing (except, maybe, some HPF to get rid of stuff that might mess with the preamp) into the computer then do all processing on a copy of the original file.
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Re: Bulk Digitizing Old Cassettes

Postby ef37a » Wed Dec 05, 2018 7:49 am

What they ALL said plus don't forget to backup the raw recordings, maybe at the end of each session? You have hours of work ahead of you, be a shame to lose it.

You can get a portable 1TB USB 3.0 drive for around £50.00 (stick some in a "cloud" as well but I don't trust 'em!)

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Re: Bulk Digitizing Old Cassettes

Postby ken long » Thu Dec 06, 2018 11:01 am

Mobileman wrote:The show means a great deal to her and she would like to preserve them for her lifetime on CD's.

Then she shouldn't be putting them on CDs.

James' advice is the best on here. The muffled sounds may be the oxide on the heads or it may be the head alignment is way off. Those are the two things you should focus on. Yes there are tools for post processing but they won't restore that which was never captured.
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Re: Bulk Digitizing Old Cassettes

Postby ef37a » Thu Dec 06, 2018 11:20 am

ken long wrote:
Mobileman wrote:The show means a great deal to her and she would like to preserve them for her lifetime on CD's.

Then she shouldn't be putting them on CDs.

James' advice is the best on here. The muffled sounds may be the oxide on the heads or it may be the head alignment is way off. Those are the two things you should focus on. Yes there are tools for post processing but they won't restore that which was never captured.

Ooo! I think CD is going to last this lady out? She could also dump them as 320k MP3 on a DVD and a USB stick. Between them I would bet that data would be readble for at least another 50 years?

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Re: Bulk Digitizing Old Cassettes

Postby Sam Spoons » Thu Dec 06, 2018 3:14 pm

If she's a technophobe, make three copies of every CD and she should be fine for a very long time.
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Re: Bulk Digitizing Old Cassettes

Postby ken long » Thu Dec 06, 2018 4:12 pm

ef37a wrote:
ken long wrote:Ooo! I think CD is going to last this lady out? She could also dump them as 320k MP3 on a DVD and a USB stick. Between them I would bet that data would be readble for at least another 50 years?


Maybe. But if she hasn't got a player to read them in 50 years, the recordings won't be easily accessible.

File based formats, properly backed up, is the way forward. Cloud storage is a doddle to use nowadays.
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Re: Bulk Digitizing Old Cassettes

Postby ken long » Thu Dec 06, 2018 4:14 pm

Sam Spoons wrote:If she's a technophobe, make three copies of every CD and she should be fine for a very long time.


CD-Rs have a life expectancy of ten years.
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Re: Bulk Digitizing Old Cassettes

Postby Sam Spoons » Thu Dec 06, 2018 4:30 pm

Well I have plenty much older than that which still work fine. According to this page, once burned they should last much longer (potentially 50-100 years). https://searchstorage.techtarget.com/definition/CD-R-shelf-life
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Re: Bulk Digitizing Old Cassettes

Postby James Perrett » Thu Dec 06, 2018 4:34 pm

ken long wrote:CD-Rs have a life expectancy of ten years.

My personal experience is that good (ie Taiyo Yuden) CD-R's last at least 19 years with little or no degradation. This won't be true of all types of CD-R though. Taiyo Yuden's quoted life expectancy for these discs was 80 years. Mitsui claimed over 100 years for their discs but I had one batch start to fail after only a year or two.

I'd agree that CD may not be the best destination nowadays though - there are plenty of devices that will play from a USB memory stick so this may be more convenient but I like to have everything backed up in at least 3 different places if possible.
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Re: Bulk Digitizing Old Cassettes

Postby ken long » Thu Dec 06, 2018 5:18 pm

edit
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Re: Bulk Digitizing Old Cassettes

Postby Mobileman » Thu Dec 06, 2018 8:37 pm

All of you are awesome, I feel like I just earned my doctorate in "Advanced Cassette Digitization." Seriously, there is a wealth of solid, workable knowledge. Two very good suggestions are leaving them unprocessed, just transferred since the material will be preserved, as it is, and nothing more. This is difficult as I am not an audiophile by any means but it seems almost disrespectful to record a musical performance with more noise than music.
The low -pass filter should provide a great deal of relief for the listener, even if it does nothing to enhance the musical details. I'm not sure how to apply this at the input, but even without much experience a trial version of Ableton Live has in?out channel routing (or looping if that'a the the correct term). Though you can't save files with the trial version, I don't think it would be against the law to capture the playback and save it with another DAW.
Lastly, mentioning Izotope RX suggests a real easy solution. The newest version offers a features that listens to a sample, suggests presets to improve and then applies them automatically to the files.
All of this suggests that even though we have long thought of mixed music as impervious to "un"mixing, the future holds all sorts of possibilities.
Again, thank you all for your very kind concern and assistance. I'll try to let you know what transpires. Happy Holidays.
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Re: Bulk Digitizing Old Cassettes

Postby Tim Gillett » Fri Dec 07, 2018 12:43 am

Hi again Mobileman,

You seem to assume that the very muffled, noisy sound you report hearing is the best that can extracted from the cassette tapes. James, myself and Ken, all of whom have done this as paid work for many years have been trying to suggest the tapes may actually contain significantly better sound quality than you have been hearing.

None of us here knows what sort of playback machine you have been auditioning the tapes with, or its condition. Could you describe it?

As Ken wrote: "Yes there are tools for post processing but they won't restore that which was never captured."
For starters, before playing a cassette, have you tried James suggestion to carefully and thoroughly clean the tape path in your machine ?
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Re: Bulk Digitizing Old Cassettes

Postby MOF » Fri Dec 07, 2018 2:47 am

Don’t have the Dolby button engaged when you transfer the tape. Misalignment between the record and playback machines can cause a muffled sound. Better to have a slightly brighter but hissier sound in your case I would have thought. If there is a tape type selector then match that to your cassette.
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Re: Bulk Digitizing Old Cassettes

Postby Tim Gillett » Fri Dec 07, 2018 5:46 am

MOF wrote:Don’t have the Dolby button engaged when you transfer the tape.

Misalignment between the record and playback machines can cause a muffled sound.

Better to have a slightly brighter but hissier sound in your case I would have thought.

If there is a tape type selector then match that to your cassette.

Yes all good points.

Keeping Dolby or other NR off is important. It's difficult to undo Dolby decoding after the fact.

With slow speed cassettes, read head azimuth misalignment is very common but even more fussy if replayed on a mono machine, or stereo summed to mono. James mentioned this early in the thread.

Yes the rule when capturing is to capture everything, including all the tape hiss. Even if it is objectionable to our ears. This also keeps the inevitable tape machine preamp hiss to a relative minimum. Maximise the program signal so that it predominates and so masks the preamp hiss. Unless the playback is maximised off the tape head, the roles can reverse, preamp noise can predominate, and the inexpert person can assume all that noise is unavoidable tape noise.
A good test when replaying a cassette is to listen from the very start of the 5 second plastic leaders at the beginning of a tape side. As soon as the actual magnetic tape hits the head there should be a noticeable increase in clear, steady, sharp hiss. That at least suggests that the tape is in reasonably intimate contact with the read head.

"Tape type" is more easily undo able as it's a predictable, static LPFilter, and at only 4db at 10kHz, is fairly mild in any case. For people with HF hearing loss it may not even be noticed. But yes, better to capture it at "Type I " setting as (in this case at least) it's most likely they were Type I tapes recorded by a machine which assumed Type 1.

Another issue is the cassettes themselves. Especially older cassettes can have a worn, or damaged pressure pad. This can cause partial or complete loss of signal. The pad is also designed to provide a certain braking force on the tape. Without this "back tension" tapes can be chewed up by the pinch roller and capstan.
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