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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 18th Feb 2021, 4:42 pm   #1
Martin Bush
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Default Head demagnetizer cassette

Good afternoon all

I have kindly been bought a cassette head cleaner and demagnetizer cassette package branded Vinyl Styl. I will include a link at the end of the post for illustrative purposes, but accept that it may be removed by the mods if its inclusion isn't in line with forum rules.

I know what the fluid is for, and I know how to clean heads, rollers and capstans, so I don't need a view on that angle. Nor on the price etc.

What I want to know is whether it will actually demagnetize the heads as stated. At present I don't have a hifi deck (I used a personal stereo which is serving very well at the moment) but when I do I want to treat it well. It may be worth me buying a dedicated gadget for demagnetizing but wondered is this one would actually do the job.

Martin

https://www.juno.co.uk/products/viny...SAAEgKrw_D_BwE
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Old 18th Feb 2021, 4:53 pm   #2
Nickthedentist
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Default Re: Head demagnetizer cassette

Hi Martin,

I think that little spinning wheel is meant to do the demagnetizing, but I've never understood how the alternating magnetism they produce is meant to die away to nothing; I've always thought that was a fundamental part of the degaussing process.

More elaborate cassette demagnetisers existed, which had an electonic oscillator powered by a couple of coin cells. I'd trust one of these more.

I have a cheap mains powered unit which you'd be welcome to use. It only takes a few seconds.

N.
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Old 18th Feb 2021, 5:09 pm   #3
Martin Bush
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Default Re: Head demagnetizer cassette

Thanks Nick - I may take you up on that. I will need a cassette deck first of course (I have plans for one when we move house).

But yes, I'm not remotely scientifically minded, but I am intrigued as to how the cassette might work. They claim it does on the packaging, so you'd expect that it had to by law...
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Old 18th Feb 2021, 11:34 pm   #4
knobtwiddler
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Default Re: Head demagnetizer cassette

Quote:
Originally Posted by Martin Bush View Post
Thanks Nick - I may take you up on that. I will need a cassette deck first of course (I have plans for one when we move house).

But yes, I'm not remotely scientifically minded, but I am intrigued as to how the cassette might work. They claim it does on the packaging, so you'd expect that it had to by law...
By law? We are talking about the audio industry here...where firms can charge you hundreds for a rock that sits by your hifi, 'absorbing' stray magnetic fields...

In terms of demagnetising, for a product that must cost under 2 to make (OEM margin, distro, shop, VAT), I can't see it being effective. If people debate whether pro-grade, mains-powered demagnetisers even have an effect (in the cassette world - not studio, where they are de-facto), then will a magnet in a product that cost under 2 to make do something?

Do you have a scope + oscillator? If you record a 15KHz sine @ -10, then play it back on your walkman, pre and post usage of this device, and you see an increase in level, I will eat my hat live on Youtube.

In the 70s and 80s, cleaning tapes that contained a fabric tape, which one wetted with alcohol, were common. Personally, I always felt they were useless, and if anything, the deck sounded worse after using one. When the Allsop 3 cleaner came along it was an absolute revelation. Better than cotton buds, as it cleaned everything evenly by default.

Sorry if I'm pouring water on your fire.

NB - make sure to learn the technique before you use Nick's demag. It's very easy to damage a head with one.
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Old 19th Feb 2021, 12:28 am   #5
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Default Re: Head demagnetizer cassette

I do own a head demagnetiser, and it does use an oscillator powered by a couple of AG13s. It uses what looks like a cassette head which is moved backwards and forwards by the mechanism. It didn't cost a fortune when I bought it in the 80s, but I'd expect the prices to have gone up since then.

My experience has been that cassette heads don't magnetise easily in normal use.

You can't beat meths or IPA on a cotton bud to clean tape heads. The bottles in the kit that you reference probably contain IPA or ethanol plus some water. Cleaning cassettes should only be used as a last resort, where access to the head with a cotton bud is difficult or impossible. HiFi decks are normally easy to clean with a cotton bud or a bit of rag or bog roll, as are Walkman type players. It's car players that are a real PITA.
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Old 19th Feb 2021, 12:50 am   #6
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Default Re: Head demagnetizer cassette

Most decent tape recorders including cassette ones have a bias oscillator with a decoupling capacitor that should be of sufficient size that a reducing AC signal should exist on the head every time record is disengaged. Provided the head shield/casing is non magnetic there is unlikely to be a need to do anything apart from engaging record on the lead out of a tape or on a blank tape every so often.
Players are another matter and DC bias units are not worth the bother.
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Old 19th Feb 2021, 11:41 am   #7
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Default Re: Head demagnetizer cassette

>Cleaning cassettes should only be used as a last resort

Do you remember the Allsop 3 one? It does the same thing as buds, but in an automated manner, where a pair of cogs drive a fabric pad back / forth across the head. The beauty of the Allsop is that it scrubs the capstan spindles, rollers and play / rec heads equallly. There is a debate about whether IPA is bad for rollers, i.e. it dries them out.

The Allsop was patented, and spawned a few clones. With the exception of the Allsop, I would agree 100% that cleaning cassettes ought to be avoided.

NB - for those of you fortunate enough to own a Nak, I'm not sure how well the Allsop will work with the pad lifter.... It may also leave the rec head unaffected in other discrete head decks, so you'll still need to get the buds out.

edit - and another good point that Paul makes is about the 'liquid' supplied in the bottles. The Allsop was the only cleaning cassette that I ever saw to provide pure IPA. Others had all manner of useless solutions in them, which may well have contained water. If the bottle isn't labelled '99% IPA' then it is best avoided. In a factory that churns out millions of cleaning gadgets, saving on IPA costs is attractive.

Last edited by knobtwiddler; 19th Feb 2021 at 11:48 am.
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Old 19th Feb 2021, 5:01 pm   #8
Martin Bush
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Default Re: Head demagnetizer cassette

Not wanting to go too far off topic, but as regards cleaning pinch rollers, what is the best approach?

I have to admit that I have used IPA on cassette pinch rollers and also those in 8 Track cartridges. I use it to get the muck off and don't over use it I don't think.

I have seen someone on another forum state that they use Lenor. I don't know how you would find yourself trying that out for the first time, but he swears by it. I think I will give it a miss unless someone has evidence that it's a good idea.

So, having said all that, I am keen to be using the right stuff as it's the rollers that I think are the biggest risk on the tape path.
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Old 19th Feb 2021, 10:39 pm   #9
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Default Re: Head demagnetizer cassette

I think rollers are a paradox. Anything that leaves a residue (Lenor) is strictly verboten. You want something that's capable of breaking down the sludge and evaporates quickly, which leads you towards a solvent - but then you have the *oft-cited* issue of parching out the 'rubber'. Rollers harden and need replacing whatever you clean them with. Considering how quickly IPA dries, I have to wonder if it's been scapegoated for something that occurs naturally with rollers?

Another thing to note is that rollers may not be 'rubber', as there are quite a few polymers with rubber-like qualities that could be used. It could be the case that some are more sensitive to IPA than others. IPA is what I've seen used in studios. In the world of cassettes, the only thing I've seen that's guaranteed to really get the brown marking off the rollers is the Allsop cleaner I mentioned earlier. If you're nervous about drenching the rollers, just moisten the pads slightly

Here is a previous thread: https://www.vintage-radio.net/forum/...ad.php?t=15586
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Old 20th Feb 2021, 6:30 am   #10
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Default Re: Head demagnetizer cassette

There is an excellent cleaning spray for rubber form Teslanol, called GR (Gummi Reiniger). It's extermely fast drying. According to the material data sheet one of the main components is IPA, but there are also other hydrocarbons in the mix. (I don't personally spray it directly on rubber surfaces, I spray it on a rag and use the rag to clean the rubber).

I'm certainly no chemist, but it would seem to me that the faster the solvent evaporates, the less chance of it taking softeners etc from the rubber, as opposed to a solvent which evaporates slowly and therefore has time to dissolve whatever additives there are to keep the rubber supple.

I remember once someone recommending not to use meths for cleaning pinch rollers because it dried them out. Meths, at least the variety I can get hold of, leaves a residue, so that would be the main reason not to use it, but also it certainly evaporates slower than IPA, so I've been assuming the rate of evaporation plays an important role.
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Old 20th Feb 2021, 9:18 am   #11
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Default Re: Head demagnetizer cassette

I ued to be able to get pure IPA from my Chemists, but no more. However it is easily bought online. I also recommend the aforementioned ALSOP3 cleaner which I use to this day with great effect on the Teak, NAD and the Philips Black Tulip (excellent machine!) but not on our Nak 2.
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Old 20th Feb 2021, 11:14 am   #12
knobtwiddler
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Default Re: Head demagnetizer cassette

Ah! Are you telling me that the Allsop doesn't agree with the Nak's pad lifter, Edward? This is what I suspected. It can't clean the Rec head on a discrete Nak, but I was wondering how it'd work with the lifter.

I think there's an argument for removing the head wiper and using the Allsop for the Nak's rollers / capstans alone. I've never seen anything that cleans them as evenly. And you could argue that they are the most important parts to clean. A bit of oxide on the head will impair sound, but it won't cause the machine to mince a tape.
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Old 21st Feb 2021, 4:52 pm   #13
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Default Re: Head demagnetizer cassette

I bought 99.9% IPA recently (last year) from my local chemist, or was it eBay? I can't remember now, but has it suddenly become illegal? I've always used it back in the day for cassette and R2R pinch rollers, as well as the heads, both as a consumer and professionally. I've never noticed any problems and if it's pure it evaporates almost instantly. It is true it will continue to remove rubber if you go mad but a judicial regular use is always best.

What I find more debatable often recommended elsewhere is things like using NuFinish as a regular 'lubricant', because it has a mild cutting compound in common with many car polishes and synthetic motor oils for a general bearing and motor oil, because it naturally has detergents not designed for precision bearings in other applications and is designed to work best under great pressure and heat.
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Old 21st Feb 2021, 8:53 pm   #14
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Default Re: Head demagnetizer cassette

Non-availability might just mean that the wholesalers don't think it worth carrying stocks. A couple of years ago I ran out of surgical spirit and my local pharmacist couldn't find it in the catalogue of their normal supplier. I got some on-line with no trouble.

Last edited by emeritus; 21st Feb 2021 at 8:53 pm. Reason: Typo
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Old 21st Feb 2021, 11:06 pm   #15
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Default Re: Head demagnetizer cassette

IPA now comes under the Control Of Substances Hazardous to Health (COSHH) regulations which (AFAIK) means that it shouldn't be sold to consumers. It is easily available from trade suppliers. Even in the late 1990's our local pharmacy was becoming more cautious about supplying it but were happy when I explained that it was for recording studio use and they could see our studio building from their window.

As far as cassette demagnetisers are concerned, I was always warned against their use and have used a wand demagnetiser for 40 years. I have only once encountered a seriously magnetised cassette machine which was easily fixed by the demagnetiser. This was a radio cassette which I had just acquired second-hand so I have no idea how it ended up in its magnetised state. Most of the time I just use the demagnetiser every few months as a precaution.
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Old 21st Feb 2021, 11:53 pm   #16
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Default Re: Head demagnetizer cassette

There are hundreds of sellers offering IPA on ebay. Either they are breaking the law, or it's legal.
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Old 22nd Feb 2021, 12:23 am   #17
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Default Re: Head demagnetizer cassette

I see tape path demagnetising like insurance. Before playing an important tape, I demagnetise the tape path. Not because I believe the machine is magnetised, but maybe it is. Even a slightly magnetised tape path can erase some signal, and each time the tape is played on that deck the erasing effect multiplies.

Adjusting playback azimuth is a regular thing for me so demagnetising the screwdriver or other driver is also important before getting the tool anywhere near the tape path.

On the other hand manual demagnetising has to be done carefully or we can end up making the problem worse.
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Old 22nd Feb 2021, 12:31 am   #18
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Default Re: Head demagnetizer cassette

>Not because I believe the machine is magnetised, but maybe it is

The Schrodinger technique -)

If you do demag a deck, make sure to do it properly. Never touch a head! Heads scratch easily. I haven't done it in years, so will need to practise, as I have a pile of precious tapes to transcribe.

NB - I think Tim's advice is excellent. As long as you do it properly!
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Old 22nd Feb 2021, 8:16 am   #19
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Default Re: Head demagnetizer cassette

There was a service bulletin on the Revox B710 discouraging routine use of a demagnetiser on the grounds that it led to premature demagnetisation of the capstan motor rotors. In practice, these machines seldom mag up outside of fault conditions.
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Old 22nd Feb 2021, 8:55 am   #20
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Default Re: Head demagnetizer cassette

Years ago I had one of those mercury powered cassette demagnetizers, it was next to useless and as Ted and others said, cassette heads never seem to get magnetized - I think maybe because the combined rec/pb in most self demagnetizes anyway? There are times a head can become magnetized, e.g. if you test them for impedance with an ohm meter, but it is other wise very rare. My deck has a removable headlock fortunately and needed serious realignment, when I bought it. After that, I demagged it away from the machine, as a precaution. The major danger is getting the wand near VU meters in situ.
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