Demagnetising... is it really needed.

Smithers XKR

Well-known member
I think old technology is a waste of time if it ties a hand behind your back, but some of it still works pretty well - so why not keep using it? Some of course, was rubbish when new. Things like Philips laserdisc - it was pretty good technically, but nobody wanted to buy them. I had a digital recording system in the late 90s - Soundscape. I bought it because the BBC were using it locally. Dedicated cards for the PC - so I had the software and 16 tracks of digital in and out and it was really, really horrible. The software was the problem. The cards I carried on using for quite a while till there were no more drivers. Everyone understand windows and how you drag and drop, select things with mouse clicks and that really basic stuff. Soundscape did everything differently and it was just nasty to use. It was pretty reliable - but just totally non-intuitive. Cost a damn fortune too. Dumping it and carrying on with Cubase was the best thing I did.
You also have to understand that, I am a man of relatively humble means, I am not rich. So with that in mind if I decided to ditch the old gear what would I do with it? Sell it on eBay and I would get bloody sod all, pennies. So I will just be stubborn and bloody minded and vow to keep using the stuff 😅😉👍
 

Slouching Raymond

Well-known member
My only experience of de-magnetising was in erasing tapes. Wiping the contents completely.
You would place the loaded tape spool into a gap in a very meaty magnetic field generator,
and it would cycle the field many times, gradually reducing the field strength. This was required
to overcome the hysteresis in the magnetised tape.
 

Smithers XKR

Well-known member
My only experience of de-magnetising was in erasing tapes. Wiping the contents completely.
You would place the loaded tape spool into a gap in a very meaty magnetic field generator,
and it would cycle the field many times, gradually reducing the field strength. This was required
to overcome the hysteresis in the magnetised tape.
Yes Ray, from what I have managed to research and learn it is a bit of a minefield. Degaussing is removing the magnetic field that has built on Ferric based magnetic analogue tape machines. Whereas demagnetising refers to the permanent removal of magnetic properties or erasing, so this could be relevant to the actual cassette or reel to reel tapes themselves. Then into that equation comes the aluminium based digital format. DCC and DAT machines use Aluminium fixed heads so do not get magnetised and ADAT and VCR uses the Aluminium drum rotating head system.
So in theory these mechanisms will never be subject to Ferric style magnetism. But then you have the steel capstans in the machines which CAN become magnetised to a degree
I just think it is all a bit of a minefield, and on balance I will stay away from the digital or VCR format and just use the degausser on my Ferric based analogue heads.
Cheers 😉👍
 

Smithers XKR

Well-known member
My only experience of de-magnetising was in erasing tapes. Wiping the contents completely.
You would place the loaded tape spool into a gap in a very meaty magnetic field generator,
and it would cycle the field many times, gradually reducing the field strength. This was required
to overcome the hysteresis in the magnetised tape.
The way I see things is.... I seek advice from you more knowledgable guys here, I go on the web and try to learn and gain as much knowledge as possible, then I try to filter out all of the misinformation and try to make the final judgement for myself. I hope that makes some sort of sense and sorry if it sounds a bit selfish. So apologies
 

rob aylestone

Well-known member
Do you remember when we did loads of cassette duplication of news for blind folk - posted out each week, then returned. We had bulk erasers for these, and different ones for reel to reel tapes. I think the one I had was made by Weircliffe - <img src="https://thumbs.worthpoint.com/zoom/images1/360/1112/04/weircliffe-bulk-eraser-model-vintage_360_a6f49ab599ce2dc965094ef0fc55cabb.jpg" alt="WEIRCLIFFE BULK ERASER MODEL 8 / VINTAGE / EXCELLENT CONDITION (image 1/4)" /> In a big wooden box. you posted the tape into it, and pressed a button. A huge magnetic field scrambled the recording and then it slowly died away to nothing. I remember mine worked fine on the reel to reel tapes I had in the 70s. It couldn't erase Chrome Dioxide tapes though - it always left a trace of the old recording.

If you want to just demagnetise a head you can get one for twenty five quid? In all the years I as a teenager used them, the only problem was just making sure you didn't touch the heads - and most of the ones I used had a plastic sleeve so that even if you did, accidentally, you didn't damage them.

The only thing to know in advance is that you must power down the machine, because the 50Hz blast of hum through the speakers can be quite nasty, but the worst thing, that nobody mentions is that the things vibrate when they are in the vicinity of the sort of metals that they work on - you can feel the magnetism working. A strange sensation.

All I know is that when you make a vital reel to reel recording, or a cassette recording - then you clean the heads and tape path and you demagnetise. It is like checking tyre pressures. You know you should, but usually don't. It is just good practice, and a good habit. It really is no big deal to do. Place close, turn on, move away across the room, switch off. That really is it.
 
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