Tape degradation

[ricard]

In this thread https://www.vintage-radio.net/forum/...d.php?t=190356 the OP commented on how good his old recordings sounded.

When discussing old recordings with random people I often get the question "won't the recordings have self erased after all this time", and I always reply that the recording itself will not degrade just because it's old. Of course, there may be tape issues such as sticky shed, or acetate tapes that have suffered from vinegar syndrome. Or some early metal particle tapes which basically rust because the metal particles were not properly encased. But these are specific issues due to the chemistry of specific types of tape and not a general problem.

Desintegrating pressure pads in cassettes are another culprit, which perhaps is one of the sources of this myth - I'm thinking that people get out old cassette tapes, and find that they don't play well and immediately assume it's because the tape has lost its magnetization.

What say other forum members, do you also hear the "recordings degrade on their own" myth a lot?

[brenellic2000]

One issue is that the audio quality/capability of audio tape and tape recorders in the 1960's varied considerably between brands; I found BASF, Mastertape and Zonal to be quite consistent and reliable whereas EMI and Phillips could be quite variable. I guess we hear what we expect to hear, and not what was actually recorded!

[TIMTAPE]

Yes it seems a common misconception. Understandably most people simply dont know any better especially if they have no means to play their own recordings any more.

It's not helped by unscrupulous media transfer business owners who publically announce that customers must have their tapes digitised ASAP as the tapes are physically disintegrating, especially home movie tapes. Usually they're not disintegrating, unless stored poorly.


It's also not helped when people get their information about audio "restoration" from TV crime shows which tend to exaggerate what is possible in digitally "restoring" old recordings. So develops a low view of the fidelity and longevity of old tape recordings. When a good tape recording is played back poorly it can be assumed that's the best sound that the tape contains. When the same tape is played back properly, at its best, it can be assumed it has been "restored" with the wonders of modern digital magic. I've "restored" many old tape recordings for customers simply by doing my best to play them back at their best.

I have some reel tapes recorded in the late 40's and early 50's. It's not possible to be 100% sure but the recordings appear not to have deteriorated much over those decades of storage. They were pretty dire, unskilled recordings in the first place but that's not the point. They dont seem to have deteriorated much over 70 odd years. But to their credit the owners of the recordings stored them well over all that time. It can make a huge difference.

On the other hand I occasionally receive for transfer a tape which has been partially erased due to unskilled playing such as on a machine with a magnetised tape path. A giveaway is when often the sound starts off very noisy and muffled, then the moment it passes the point in the tape where the operator had - fortunately for them - stopped playing it on the faulty (magnetised) machine, the sound suddenly springs back into full clarity.

The inevitable customer query is: "With all your magic tricks why couldnt you make the first part of the tape sound as beautifully clear as the rest of the tape?"...

[Ted Kendall]

The field is indeed littered with popular misconceptions - including the necessity of baking any tape, however old it may be. True, some early oxides can develop devastating levels of print-through - I had to contend once with an EMI studio recording which had nine (count 'em) layers of print before the first note - in that case we went back to the 78 metals. But, generally speaking, most domestic tapes up to 1970-ish survive remarkably well. After that, the advent of polyurethane binders renders it more of a lottery, although BASF take the palm for ruggedness in my view, seldom gives trouble.

[paulsherwin]

My high quality cassette recordings from the late 70s on Japanese stocks don't appear to have deteriorated at all. Some stocks do seem to develop printhrough problems though, and some shed a lot of oxide.

[Analogue man]

I have a large number of reel to reel tapes which have been in my possession since 1975 mostly Memorex as I was offered a job lot back then but also some BASF and scotch. The Memorex is as good as new with no noticeable degradation of recordings made on them, the BASF sound as good as new too but do appear to shed quite a bit of oxide although this does not appear to effect the sound (so far).

Of the two reels of scotch one is now in need of a bake but that won't happen as the recording on it has now been replaced by a mint vinyl copy of the recording and the other has been transferred to a NOS Maxell before baking became necessary.

[jamesperrett]

For me one of the most annoying sources of the "our tapes are degrading and they won't survive another 10 years" myth is the British Library Sound Archive with their Save Our Sounds campaign. I can understand that they are using this to gain more funding but aren't the funders going to start wondering if they've been conned when these tapes are still perfectly playable in 10 or 20 years time? I feel a bit churlish complaining about this when there are obviously people there who know what they are doing but it the oversimplification really annoys me.

As Ricard says, there are certain types of tapes that are degrading but the vast majority of tapes in circulation are still perfectly playable.

[TIMTAPE]

Thanks James, I share the discomfort. Some years ago I was involved in a large digitisation project and the project title (coined before the digitising staff joined the project) clearly implied that the thousands of audio cassette recordings(!) were in mortal danger of failing hence the prominent word "rescue". In digitising the many cassette tapes we were supposedly on a rescue mission. Even then I knew this was being somewhat economical with the truth...

In my eyes, both then and now, the main benefit of the project was its giving people easy and fast access to the recordings.

[Martin Bush]

I am interested in tape degradation as I have some sealed cassettes - mainly ferric types (which sound fine to me whenever I use them) and wonder what the long term future is for these and my pre-recorded ones too. The only problem I have had is one tape, I don't know which, left some material on the head of my deck. I have a suspicion it was a pre-recorded from the 1990s, but I was slow to realise it had happened so couldn't really check. I have an original Beatles cassette which I suspect is older than me and I gave it a play a while back. I expected it to be jammed (as has been the case with some much newer pre-recordeds) or otherwise poor quality as I suspect somewhere along the way it's been poorly stored, yet it played wonderfully and sounded perfect.

Print through is mentioned above and I wondered if this is responsible for something on an LP I own. It's an original Mott the Hoople LP (ie not one pressed in the last few years) and on the first track (All the Way From Memphis) you can hear the track start very quietly for a few bars before it starts again as it should. I have read that print through can happen immediately and wonder if this is what happened here.

On the subject of Save Our Sounds etc I wonder whether it's also being treated as an opportunity to safeguard the sounds from the fate of all those original master tapes that went up in flames a few years back in America. Some unreleased recordings by big-name artists were lost along with original masters of well-known material.

[paulsherwin]

You can get printhrough effects on vinyl records (and indeed anything else) for lots of reasons. It's unusual to get printhrough on studio multitrack tapes or production masters, because the tape stock is quite dense and whizzes past at 15ips (or even 30ips.) Some reissues were made from pretty ropey dubs of the stereo masters in the 70s and 80s though, especially if the original masters couldn't be found or there were legal disputes.

Groove damage can cause an effect very like printhrough - in that case the pre-echo will be about 2 seconds (33.3 revolutions per 60 seconds.)

[Ted Kendall]

Pre-echo on discs is generally a cutting or processing matter. Tape print-through is exacerbated by high temperatures and external magnetic fields, but improved substantially as the uniformity of particle size in coatings improved. A lot of tape stock pre-1970 will play without problems, but binder failure in more modern formulations is a known hazard. A Decca XDR cassette I tried recently squealed dreadfully - being pre-recorded it didn't matter much, but it indicates the problem.

A lot of the justification for the various "rescue" programmes lies in the restricted availability of suitable replay equipment, which arguably applies to more modern formats with greater force than to quarter inch. Beta machines, DAT players, even decent cassette machines, are unlikely to be made again, so what already exists is our only means of playing back anything that has been recorded. That being so, it makes sense to digitise whatever is played to make best use of the remaining head hours. The machinery situation is perhaps a little less acute with quarter inch, but then acetate tapes are busily crumbling or turning to vinegar, whilst the polyurethane binders are equally busy breaking down. There is, in short, plenty of reason to get this stuff into digits, and a lot of the over-simplification is that necessary for an effective funding campaign in the murky world of politics.

[ben]

The point above is crucial. With all the fixation on the tape, we're forgetting the main problem: machines. Even the simplest of decks will need new drive belts fitting which often requires disassembly. Fewer people are doing this kind of repair work, as we all know.

The complexity of helical scan video formats and DAT means that the future for these is shakier than for analogue audio tape. As parts wear and tight tolerances cannot be met, it is going to be hard to recover these in the future.

[Nickthedentist]

Something that I've not seen mentioned so far in this thread: I have read online that audio cassette recordings gradually lose their HF response over the years.

Certainly, mine seem to have done this, BUT they may have been played on machines with a magnetised tape path or stored in suboptimal conditions. Or maybe my playback machines' heads are significantly worn. And I know that my hearing is not what it used to be.

[paulsherwin]

I've not noticed this with my old high quality cassette recordings, but my hearing doesn't go much above 11kHz nowadays, and I've never tried to do any lab tests. Most 40 year old cassette recordings will have spent time in less than perfect conditions, most obviously sitting on a car dashboard in hot weather or being played on poor quality equipment. Most car players were pretty brutal.

[Ted Kendall]

Suspected for ages, but not proven as far as I know. Any of half a dozen misalignments can reduce HF off tape, to say nothing of ageing machinery and changing expectations. After all, we didn't have consistent and durable sparkling top on tap domestically until CD came along.

[jamesperrett]

I've heard similar tales about metal cassettes self erasing but I don't have any personal experience of it. Normal ferric and chrome tapes don't seem to exhibit this behaviour as far as I can tell.

[TIMTAPE]

Originally Posted by jamesperrett

I've heard similar tales about metal cassettes self erasing but I don't have any personal experience of it. Normal ferric and chrome tapes don't seem to exhibit this behaviour as far as I can tell.

Popular camcorder tape formats starting in the mid 80s like Video 8, Hi 8, DV all used metal tapes. I've not come across any with obvious loss of signal. But they are very thin tape stocks and extremely vulnerable to physical damage. I just transferred 10 early Video 8's. Interestingly all were fine except for some physical wear and tear, and on the later ones the HIFi audio starts to break up, perhaps due to the notorious SMD camcorder caps fail issue. Another problem with Metal tapes is their vulnerability to water damage compared to oxide tapes which if treated quickly enough can survive quite well I believe.

[cheerfulcharlie]

Originally Posted by Nickthedentist

Something that I've not seen mentioned so far in this thread: I have read online that audio cassette recordings gradually lose their HF response over the years.

Certainly, mine seem to have done this, BUT they may have been played on machines with a magnetised tape path or stored in suboptimal conditions. Or maybe my playback machines' heads are significantly worn. And I know that my hearing is not what it used to be.

Could be my imagination? I have found it to be a creeping effect that starts at the beginning of a tape, but rather than believe our aging ears I have noticed it on old videotapes as well where busy shots of landscapes, etc lose some of their detail at the beginning of the tape.

[brenellic2000]

One of the greatest dangers of 'digital rescuing' of original material/media is - as with microfiche documents - the tendency to discard the original once the copy has been safely made. By now abandoning the redundant old technology, what happens when the new technology/media becomes unreadable (8" floppies, Amstrad disks...)? We've all 'lost' unrecoverable computer files! How many back-ups of back-ups should be made?!

[TIMTAPE]

Originally Posted by brenellic2000

One of the greatest dangers of 'digital rescuing' of original material/media is - as with microfiche documents - the tendency to discard the original once the copy has been safely made. By now abandoning the redundant old technology, what happens when the new technology/media becomes unreadable (8" floppies, Amstrad disks...)? We've all 'lost' unrecoverable computer files! How many back-ups of back-ups should be made?!

Yes it's an ongoing issue. I think pretty standard advice is to be reconciled to this problem and try to mitigate it by recopying files to new media every so many years, before the previous media have started to fail.

Storage of large and heavy original formats can be expensive over the long term but I'm also wary of jettisoning original media, and stopped doing it some years ago. But then I dont have a large archive so the choice costs me little.