How do I fix a squeaking cassette?

[Tomás Mulcahy]

I'm working on a cassette from a local library as a favour, trying to retrieve it. It has scrape flutter i.e. the mechanical squeak is causing metallic ringing noise in the audio signal. The pitch is very wobbly. It's not shedding, but it appears to have "lost" its lubrication. Is it possible to relubricate? Has anyone here done that before? I've seen some very dodgy advice on the web about using various lubricants. I've been unable to find any literature by archivists. So... help please!

[The Elf]

The old bodger's trick was to run a soft pencil around the friction points.

[Exalted Wombat]

It seems unlikely that mechanical noise from the cassette is getting into the playback signal!

This sounds as if it might be more about dirt in the tape path than a lack of lubrication. The pressure pads in the cassette may be gunked up. And don't forget to check the heads and other tape-touching parts in your player.

It might be worth transferring the tape to a new cassette body. You used to be able to buy "rescue cassettes". But they weren't really any different to a clean screw-together type cassette with the original tape discarded. You must be able to find one?

[ken long]

I'm working on a cassette from a local library as a favour, trying to retrieve it. It has scrape flutter i.e. the mechanical squeak is causing metallic ringing noise in the audio signal. The pitch is very wobbly. It's not shedding, but it appears to have "lost" its lubrication. Is it possible to relubricate? Has anyone here done that before? I've seen some very dodgy advice on the web about using various lubricants. I've been unable to find any literature by archivists. So... help please!

Yesh, I've done this but not with a cassette, with open reel. With a pipette and some isopropyl. I'm not sure how you can get to the cassette tape before it hits the heads but Isopropyl will do the trick though expect some HF loss.

[The Elf]

The old bodger's trick was to run a soft pencil around the friction points.

To be clear: I'm referring to the circular spindles in the cassette shell - not anything in the tape path!

[Dr Huge Longjohns]

Sometimes just giving it a good whack on the edge of a table does the trick, I seem to remember.

[ManFromGlass]

It seems unlikely that mechanical noise from the cassette is getting into the playback signal!

This sounds as if it might be more about dirt in the tape path than a lack of lubrication. The pressure pads in the cassette may be gunked up. And don't forget to check the heads and other tape-touching parts in your player.

It might be worth transferring the tape to a new cassette body. You used to be able to buy "rescue cassettes". But they weren't really any different to a clean screw-together type cassette with the original tape discarded. You must be able to find one?

I'm potentially one of the last people to hear things but I've heard the cassette is becoming a popular format again to sell off the stage so in theory you could find a brand new shell.
Cheers
Eric

[James Perrett]

It seems unlikely that mechanical noise from the cassette is getting into the playback signal!

Actually, it is highly likely that mechanical noise is finding its way into the audio signal. This is a very common symptom of tapes that have lost lubrication or that are shedding oxide. The first thing to try is to transfer the tape to a new housing but I know Tomas has been doing this sort of thing for a while so I would guess that this tape is beyond that. With reel to reel tapes I know that some people have reported success by using a lubricating sheet over the guides but I'm not sure how successful this would be with cassettes. It might be worth baking the tape after removing it from its shell although this treatment is normally only needed for back coated tapes.

James.

[Andi]

Pencil graphite certainly,& if that doesn't work there's an Aussie chap called Tim floating around here who appears to be a bit of a restoration expert - I'm sure he could tell you what to do!

[Tim Gillett]

Which brand and type of cassette tape is it? That may give a clue as to what the problem might be. It does sound like a binder problem.

Be wary of baking unless you have positively identified the tape and know exactly what you are doing. Cassette tapes do occasionally need baking but it seems to be much rarer than with classic open reel tape problems. A downside of baking even when done properly can be increased print through, ie; cyclical echo, especially with the thin tape bases used on audio cassettes.

Best to go to people with specialist knowledge. The link below should help you. Look under Tips and Notes and/or do a search. There is also a list of links to others with specialist knowledge in the field.

Richard has been very helpful to me in this area and is one of the top people in the world in the field of audio tape preservation/restoration.

http://www.richardhess.com/tape/

Tim

[ken long]

+1 for Richard

Also, baking does not solve this problem, IME.

This is the set up I used for open reel and it worked fine but, like i said, there was a loss of HF as a tradeoff...

[Exalted Wombat]

Actually, it is highly likely that mechanical noise is finding its way into the audio signal.

What's the mechanism for this happening?

[James Perrett]

The wanted signal is being modulated by the noise - think of it a bit like jitter as the timing of the waveform is moved from where it should be by the rapid slowing down and speeding up of the tape.

James.

[Exalted Wombat]

The wanted signal is being modulated by the noise - think of it a bit like jitter as the timing of the waveform is moved from where it should be by the rapid slowing down and speeding up of the tape.

Yes. But that's not what he said.

"..the mechanical squeak is causing metallic ringing noise in the audio signal"

The signal may well be affected by flutter. Which may well be caused by binding that also causes audible squeaking. But he's suggesting a microphonic effect.

This isn't about silencing the squeak. It's about curing what CAUSES the squeak.

[ef37a]

Two things I tried that used to work, sometimes!

Block the holes in all but one side and blow in that one, try not to get spit in there. The idea is to get enough moisture in there to kill any static.

Slap the cassette on a semi-hard surface like a car seat. Might need several tries each side. The idea this time is to repack the tape stack. Be careful not to crack the casing!

A dual loop capstan drive would probably give a silent play but such machines are now like hen's teeth. Models that come to mind are a Denon HX I had once and a Sony TC-177 which I could never afford (got the service manual for that BTW)

Dave.

[ken long]

This isn't about silencing the squeak. It's about curing what CAUSES the squeak.

You won't be able to retro-actively lubricate the tape permanently if that's what you are implying. The best you can do is lubricate the tape long enough for it to pass over the head but being careful not to over-lube as this will just end up creating surface tension which won't let the tape make proper contact.

[Hugh Robjohns]

What's the mechanism for this happening?

Probably a form of 'scrape flutter' which occurs when there is some kind of stick/slip action between the tape and the replay head. As tape slides over the heads and guides it vibrates -- much as a violin string vibrates under he action of a moving bow. The process is non-linear and the vibration frequency intermodulates with the audio signal recorded on the tape. The vibration frequency depends on the unsupported length of tape free to vibrate, as well as both its tension and elasticity, but typically it is up in the 3-10kHz range -- perhaps a little higher for a cassette tape.

Often scrape flutter manifests as a modulation noise at low level, varying in audibility with the recorded signal level, but in bad cases scrape flutter can generate nasty squeals, or more subtle metallic ringing type effects, or just low level anharmonic distortions.

Professional tape machines often employ rollers in the tape path near the replay head to damp out any vibrations, and cassettes sometimes use pressure pads to do something similar.

Occasionally scrape flutter can also be caused by the tape slipping between pinch-roller and capstan if the pinch roller has dried out and become hardened.

For the OP, moving the cassette tape to a new high quality shell is an obvious first step, since many of the tape path rollers and dampers are built into the shell. It would also be a good idea to fast wind the tape end to end a few times to loosen the pack. It then comes down to making sure the cassette machine's tape path is clean and in good condition, and that the pinch roller is still soft and grippy, rather than hard and slippery. It would also be worth trying a different replay machine, of course, as different tape back-tension, head alignment etc will alter the presence or amount of scrape flutter.

Hope that helps

H

[Tim Gillett]

Tomas,

Did you not find any good info from the link(s) suggested?

Having worked in this field, I'd suggest that if the tape has any suggestion of sticking or squealing, do not play it at all. Not even in fast wind. Perhaps especially not in fast wind! There is risk of damaging the tape irreparably.

In fact, an irreplaceable, important one off tape recording shouldnt even be let near a tape machine until all bases have been covered. At least that's the principle I try to abide by.

Minimal invasion is a good principle to keep in mind. So reshelling is not necessarily justified unless the existing shell has a problem. Good quality cassettes by makers such as TDK and Maxell are unlikely to need to be reshelled. The problem is likely to be the tape before the shell but of course there were some pretty awful shells made too. it just depends.

One technique for what Richard Hess has called Soft Binder Syndrome is as I recall, "cold play".
I kid you not when I say, the tape machine and tape are placed in a fridge to adjust to the cold temperature and then the tape is played and copied while in the fridge. The colder temperature can be enough to temporarily harden the tape and prevent the "stiction". But I'd advise not to do this either unless you are fully aware of what is involved.

Similarly, Marie O'Connell from NZ developed a wet play technique for reel to reel tapes using isopropyl alcohol as a temporary lubricant an perhaps a coolant. I think Ken Long may have been referring to this technique in the picture of his Studer machine. asa I recall Marie's machine was set up differently from Ken's though. I've not read of anyone using this technique with a cassette though. Cassettes generally seem to be much less vulnerable to stiction problems that reel to reel tapes.

Another technique used to help minimise stiction problems is to use a tape machine with the minimum number of friction surfaces for the tape to scrape against. Specially modified reel to reel machines are set up for this purpose. So all heads but the replay head are permanently removed. As much as practicable, the tape only contacts rolling surfaces.

So on a few of my workhorse classic dual capstan Nakamichis and some other machines I have permanently removed the erase and record heads and optimised the tape path for this new arrangement. These Nak models of course have a special "pressure pad lifter" which pushes that horrible little felt or sponge pad out of action. The dual capstan design does the work of tensioning the tape against the playback head. The pad itself can be a major contributor to or exacerbator of tape squeal or stiction so a standard classic Nak in itself may be enough on its own to get a good play out of a problem tape although removing the extra head(s) can help even more.

With cassettes it's a bit more tricky because half of the tape path is in the machine and the other half is built into each tape cassette! And there has to be a pretty good agreement between each half or that can cause even more problems.

An innovation of my own, as far as I am aware, has been to address the other half of the tape path issue - in the cassette shell itself. I have included a photo of such a modded shell. I chose as a shell one of the few standard types made with steel guide pins rather than plastic. Being made of harder material they can (one hopes!) give some improvement in stiction issues. I removed two guide pins, two alignment fingers and removed plastic material to facilitate cleaning of the metal guide pins in the centre where the replay head enters. So there are now four less parts for the tape to scrape against, plus easy cleaning of the two pins not normally accessible. Obviously this is a specially modded shell and not designed for normal everyday cassette play. The tape has to be installed into this custom shell just for the duration of the transfer. Extra care needs to be taken.

I have jpegs here of such a modded machine and cassette shell, plus other custom mods I've made over the years, but am having trouble uploading them to this forum, sorry. Perhaps another time.

If one or both tape reels is jammed due to a ragged tape pack that has to be dealt with carefully. To be frank, banging the shell on the edge of a desk is definitely not recommended. You might get away with it and the "popped strands" may well cooperate and be forced to sit down in the tape pack. But on the other hand you may just succeed in permanently destroying the smooth edges of the proud segments of tape, making intimate tape to head contact impossible. Cassettes use very narrow tracks which lie close to the edges of the tape.

Also, really fast winding a tape often has the exact opposite effect to intended, creating a more jagged tape pack which is more likely to jam because of its greater overall width. Just as with reel to reel tapes, the slow, steady "play wind" or "library wind" applies with cassettes also and makes for the best tape pack.
As mentioned, some of my favourite replay cassette machines are most of the classic dual capstan Nakamichi's but their fast wind speed is often too fast for a good tape pack and I try to avoid using that feature, rewinding in a slower gentler machine, if a true play wind is not possible. Even much cheaper machines can have a much more desirable fast wind, even if the rest of the machine is not up to much.

It goes without saying that the replay machine itself should be fastidiouly maintained and aligned for best audio results and avoiding more damage to the recording. A machine with magnetised heads, misaligned heads or guides, too much or not enough take up tension, or back tension, damaged pinch roller, or even just a faulty or missing felt pressure pad in the shell can ruin a tape in no time. Unlike common reel to reel tapes cassette tapes are usually much thinner and are easy to damage.

Even reshelling has to be done with great care to avoid damaging the tape. A clean workspace, good lighting, cotton gloves, non magnetic tweezers, a steady hand and lots of patience are necessary. A special heavy work jig to hold the cassette shell in place also helps.

Again, an irreplaceable, important one off tape recording shouldnt really be let near a tape machine until all such bases have been covered.

Hope this helps

Tim

[Martin Walker]

Hi Tim,

Wow what a great post, with SO much inside knowledge

Many thanks for taking the trouble to type all that in!

Martin

[ken long]

One technique for what Richard Hess has called Soft Binder Syndrome is as I recall, "cold play".
I kid you not when I say, the tape machine and tape are placed in a fridge to adjust to the cold temperature and then the tape is played and copied while in the fridge. The colder temperature can be enough to temporarily harden the tape and prevent the "stiction". But I'd advise not to do this either unless you are fully aware of what is involved.

Hi Tim. I know this technique isn't au point yet and he himself has been unable to confirm. He does mention his A810 seized up in the fridge and that he only really got an A77 to work/fit in there. Everything else emanated to much heat and the fridge couldn't keep up.

Similarly, Marie O'Connell from NZ developed a wet play technique for reel to reel tapes using isopropyl alcohol as a temporary lubricant an perhaps a coolant. I think Ken Long may have been referring to this technique in the picture of his Studer machine. asa I recall Marie's machine was set up differently from Ken's though. I've not read of anyone using this technique with a cassette though. Cassettes generally seem to be much less vulnerable to stiction problems that reel to reel tapes.

Yes, using Mary's idea though might try D5 (decamethylcyclopentasiloxane) which is what Richard uses. The problem I've had with isopropyl is that it tends to dissolve the capstan oil and badly affects the tension on take up. Not sure how this would translate to cassette though.

FAO Tomas:

From Richard's site:

The technique illustrated in this post is not as conserving of D5 as the technique I use for cassettes which is to use a hypodermic syringe to inject very small amounts into a cotton swab placed in the cassette shell on the supply side. So I thought I should purchase more. The up-side of the open-reel technique is that it’s very fast to set up and easily controllable. The downside is there is a small puddle under the heads, but this stuff evaporates and I was using one of the “second string” APRs. Also, the Sony APR-5000 series does not have many mechanical linkages that would be upset by excessive lubrication and its large-diameter ceramic capstan and hard-rubber pinch roller seem pretty immune to any issues relating to the D5.

taken from: http://richardhess.com/notes/2012/10/09/source-for-d5-decame...

Hope you get it sorted! Please let us know the brand of the cassette if you could.

Just a quick edit to add that, although obvious, care should be taken when handling and using any chemicals.

[ef37a]

Interesting tho' all these various techniques are the fact remains that some cassette mechanisms squeaked from new!

The blow it and slap technique (shut up at the back Zen!) is therefore decades old.

Dave.

[Tomás Mulcahy]

Wow, tons of responses, thanks folks!

Thanks especially Ken James and Tim. James is right, been at this lark for a while and I have tried reshelling. Maxell XLIIS are an excellent shell but it's not doing the business in this case. Also as I said in the OP it's scrape flutter. Tim my deck is decent although unfortunately not capstanless. I will try a different deck, I have a Tascam 122 II available to me. Tim the fridge idea sounds like it's worth a try. I had tried the Hess site before I came here.

I'm sure the tape itself needs lubricant. It's not shedding, as I said. Ken I'll try isopropyl, but need to figure out how to get it into the cassette! And I would be concerned about what it will do to the rubber pinch roller.

And this is not a rare one off tape- it is a discontinued Irish commercial release from 1989 where the only CDs currently available are £50 on amazon. We're using it as a test! It's squeaking because it was extremely popular in a public library. We have a large collection of cassettes of much more interesting Irish music that is now impossible to find commercially. We want to make it available to music students- there are three music colleges in the city. And before anyone starts on copyright issues- don't! The library has arrangements made, they know what they're doing.

[Tomás Mulcahy]

Found some more info from Hess, thanks Tim. He uses Decamethylcyclopentasiloxane or "D5" not isopropyl. It looks like it would not cause HF loss or other damage. Does anyone know where I could get that? I guess I could try the chemistry department at work... And then there is the problem of dispensing it inside a cassette deck. I will have to jerry rig something.

[ken long]

Hi Tomas,

UK -

http://www.sigmaaldrich.com/catalog/product/aldrich/444278?lang=en&region=GB

https://uk.vwr.com/app/search/Search?keywords=Decamethylcyclopentasiloxane&search.x=foo&searchOp=and&submit.x=0&submit.y=0

Prices are a little bit steep.

[Tim Gillett]

Tomas,

Is it possible your cassette machine has a fault in it which may not be apparent on other tapes but creates audible problems on this tape? For example, if the pinch roller rubber is going hard, or has too weak pressure against the capstan shaft, or the felt pressure pad is faulty, or there is too much back tension on the supply side, or any combination of these factors, you may well get stiction, or the appearance of it.

You may be able to get a pefectly acceptable pass of this tape just using a cassette machine that is simply working optimally. But unless skilled in servicing tape machines, most people probably arent in a position to establish the condition of their machine in all its parameters with any certainty.

Cheers Tim