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Topic: Archiving 4-Track cassettes > Digitally.. (Read 3145 times) previous topic - next topic
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Archiving 4-Track cassettes > Digitally..

Alright, so I've had a rather large box of multitrack cassettes (from back when I was still in high school) collecting dust upstairs for years now...  I had the idea of digitizing them some time ago, but at the time didn't have all of the proper equipment to do so. 

Anyway, I've finally got my hands on a multitrack cassette recorder with dedicated tape-outputs (this was the main thing I did not have).  I've got each individual track running into separate inputs of my E-MU 1616m.  I've created a nice Cubase template and got everything set up and tidy...

So now a few questions for those knowledgeable:

- These tapes have been sitting around for quite some time...  They haven't to my knowledge been in any real extremes of temperature and/or humidity, but is there anything I should (or should not) do to the tapes themselves prior to recording them to PC?  Example being, should I FFWD the tape to the end and then REW back to beginning to "loosen" the tape, or anything along those lines...  ?   

- I've also found a few tapes where the tape itself has snapped...  Back in the day I remember fixing quite a few tapes that this happened to by openeing them up and using a small bit of transparent tape to reattach.  Any tips or tricks for attempting tape surgery such as this?

- Is there really any overwhelming need to record higher than 16-bit/44.1kHz?  My audio interface can do up to 24-bit/192kHz, but I think this will be a bit overkill...  Also anything that will eventually find it's way to CD will be re-sampled to 16-bit/44.1kHz anyway right?  I have about 200GB free at the moment, but keep in mind that I have at least 150 cassettes to archive, which leads me to my next question...

- What would be an ideal storage solution for the backups?  ...I plan to record them straight into Cubase, and then convert the resulting WAV files in the project folders to FLAC to reduce size.  I have a stack of 20GB hard drives that I can use, or I could buy a bunch of DVDs to burn to...  Suggestions?  if DVD. ...DVD-R or DVD-RAM? etc,,,

Thanks in advance...  I appreciate any help/links/tips/tricks/suggestions/horror stories/things to avoid or definitely do/etc.

Archiving 4-Track cassettes > Digitally..

Reply #1 –
Rewinding through fast forward is generally a good idea for any tape that has been setting very long.

Keeping the tape playback mechanism clean never hurts and can save tapes from destruction.

Independent azimuth alignment of playback head to each individual cassette will improve quality of transfers.

Professionals cringe at the very thought but I’ve often used Scotch Magic Mending tape to repair breaks in tape. There is a proper solution but finding that type of repair tape isn’t so easy any more. Likewise, it was once easy to buy the alignment/cutting guide blocks used to help get good joins but unless you have quite a bit to spend you will probably have to wing it.

16 bit/44.1kHz is definitely adequate to capture everything. Analysis of a few recordings may reveal that 44.1kHz is overkill. 24kHz or 22050Hz may be quite adequate for everything except the HF noise. This will reduce your storage requirements significantly. Some high quality lossy compression might also be useable without noticeable degradation.

Archiving 4-Track cassettes > Digitally..

Reply #2 –
My experience with a half dozen different cassette decks, and cassettes from many sources, has been that essentially all tape playback produces a fairly low signal level. I’m sure it is not impossible to find the opposite, but you may want to consider having a mixer or line-level preamp available to boost the input to the soundcard. Of course, the more tracks you have, the more channels of amplification you need, which obviously increases costs.

Archiving 4-Track cassettes > Digitally..

Reply #3 –
Quote
Rewinding through fast forward is generally a good idea for any tape that has been setting very long.
I had thought this, but was a bit hesitant at first, thanks.

Quote
Keeping the tape playback mechanism clean never hurts and can save tapes from destruction.
Is rubbing alcohol (91%) sufficient, or should I find some special type of cleaner...?  Is the alcohol potentially harmful to the rubber pinch-roller thingy?

Quote
Independent azimuth alignment of playback head to each individual cassette will improve quality of transfers.
Sounds a bit complicated...  Is this something an end-user such as myself can accomplish without some sort of technical training?

Quote
Professionals cringe at the very thought but I’ve often used Scotch Magic Mending tape to repair breaks in tape. There is a proper solution but finding that type of repair tape isn’t so easy any more. Likewise, it was once easy to buy the alignment/cutting guide blocks used to help get good joins but unless you have quite a bit to spend you will probably have to wing it.
Yes, I've fixed my share of snapped tapes back in the day, so I should be able to wing this.

Quote
16 bit/44.1kHz is definitely adequate to capture everything. Analysis of a few recordings may reveal that 44.1kHz is overkill. 24kHz or 22050Hz may be quite adequate for everything except the HF noise. This will reduce your storage requirements significantly. Some high quality lossy compression might also be useable without noticeable degradation.
I'll do a few test runs at 16/44.1 & 24/22.050 and compare.  I have a feeling some of the recordings might benefit from lack of HF tape hiss and such...  Storage space might not be a problem in the long run though.

Quote
My experience with a half dozen different cassette decks, and cassettes from many sources, has been that essentially all tape playback produces a fairly low signal level. I’m sure it is not impossible to find the opposite, but you may want to consider having a mixer or line-level preamp available to boost the input to the soundcard. Of course, the more tracks you have, the more channels of amplification you need, which obviously increases costs.
Yes, a few of these recordings are fairly low-level, but boosting the signal via my audio interface seems to especially boost the tape hiss.  Is there a benefit in doing this while transferring versus post-processing? 

---

A couple more... 

Is there any good/feasible way to deal with wow/flutter in any audio editing suites?  I haven't run into much of it, but a few of the older tapes seem to have a bit of a problem. 

Is a head de-magnetizer worth looking into?  What effect would de-magnetizing the head have on the end result of the played-back sound?

Thanks for your insights.

-Aaron

Archiving 4-Track cassettes > Digitally..

Reply #4 –
Quote
I'll do a few test runs at 16/44.1 & 24/22.050 and compare. I have a feeling some of the recordings might benefit from lack of HF tape hiss and such... Storage space might not be a problem in the long run though.

You could just record at normal rate such as 48000 Hz, 24-bit and play with downsampling or lowpassing in your audio editor.
 

Archiving 4-Track cassettes > Digitally..

Reply #5 –
I can’t think of any reason to increase the bit depth to 24 just because you have decreased the sample rate to 22050.

Isopropyl alcohol works well enough. I use 99% but 91% is probably good. Sometimes there are lubricated bearings. It isn’t good to let the alcohol get into them as then the lubrication come out.

I don’t know if multi-track cassette decks are any different than the usual distribution cassette decks in this respect. The alignment of the playback head relative to the tape can generally be varied by way of a spring loaded screw holding the plate on which the head is mounted.

Ideally the recorded tracks run exactly parallel to the tape at exactly the correct distance from the edge. In practice there are large differences due to the recording head not being correctly aligned when the tape was recorded or duplicated. To adjust, the screw is turned (very slowly) while listening to the particular cassette. The higher frequencies are your guide. They are most strongly effected (diminished) by the recorded track not correctly matching the tape head gap.

For two head decks, adjusting the playback head also effects the recording head. Getting the recording head back into correct alignment is much more difficult and requires an expensive alignment cassette, so this needs to be considered if you plan on recording with the deck.

Signal level. There is noise on the tape. There is noise in an mixer or preamp. There is noise in the soundcard.

For a good soundcard, the intrinsic noise is not a factor when recording from tape. Therefore, amplifying the signal to get it above this noise isn’t really important. Quantization noise is more significant at low recording levels. Recording at 24 bit can help with this but generally will not make a noticeable difference. If you do benefit from recording at 24 bit, you can then normalize, then resample to 16 bit. What are the general peak and RMS average levels of your recordings?

A mixer preamp may add significant noise but it doesn’t require great quality for the mixer noise to be well below tape noise. Therefore most mixers are adequate, noise wise for this task.

The noise from the tape will not be increased by post cassette deck amplification. It is fixed, relative to the audio. It will become more obvious if amplified, but it doesn’t matter whether you amplify it before the soundcard or in the software after recording.

“normal” cassettes have pressure pads behind the tape where the tape comes into contact with the tape head. This wears, decomposes, falls off. Playback quality suffers greatly when this happens unless the tape deck compensates with dual capstans. What does your deck sport? Other than this mechanical consideration, I don’t know anything to do for wow and flutter except the rewind to even out tension.

Tape head demagnetizing is generally recommended. Running recorded tape over anything with a magnetic field effects the recording. Higher frequencies are effected most readily. Deterioration is generally slow, it creeps up over several plays.