Tape head demagnetiser - UK - £3.00

[Count Arthur]

I found this kicking around and as I no longer have a cassette deck and I'm unlikely to get another, I've no use for it.

£3.00

Suitable for reel to reel or cassette tape machines
Whilst your reel to reel or tape cassette player is drying after cleaning, you should always take the opportunity to demagnetise the parts the tape passes through during playback, to ensure the best quality sound reproduction.

1) Turn the power off on the tape recorder. Demagnetising with the power on can damage the circuitry.
2) Turn the demagnetiser on well away from tape or tape machines (3' or greater).
3) Move the demagnetiser in so the tip contacts the parts of the tape recorder you are trying to demagnetise. You want to do the heads, guides, and the capstan.
4) Move across the surface of each part and from one part to the next very slowly and smoothly. If you slip and move fast, go back over that part.
5) After you have gone over the surface of every metal part in the tape path, very slowly and smoothly move the demagnetiser away until you are at least 3' away.
6) Turn the demagnetiser off.

 

[Count Arthur]

Now on Ebay: https://www.ebay.co.uk/itm/164551290965

 

[Harmonie]

I have the same sort (with an EU plug), no idea where it is, but won't bother selling it

 

[egellings]

I have the R. B. Annis Co. Han-D-Mag demagnetizer and it works like a charm.

 

[Vini darko]

I have a old cassette deck(1988 pioneer ct443). This might be a fun toy. Its another item on the repair project list as record isnt working. Playback is very good though. I'll go chuck a bid on ebay.

 

[Count Arthur]

This might be a fun toy.

It's really not very exciting, it has no moving parts, no lights, nothing. You plug it in and wave it around, but there's no indication that it's actually doing anything.

 

[MakeMineVinyl]

I have the R. B. Annis Co. Han-D-Mag demagnetizer and it works like a charm.

For professional or serious home use, there is no other choice. You can get them on Amazon.

 

[Harmonie]

It's really not very exciting, it has no moving parts, no lights, nothing. You plug it in and wave it around, but there's no indication that it's actually doing anything.

Now isn't that snakeoil ?

Naaa, it's too cheap to be considered as such

 

[MakeMineVinyl]

Now isn't that snakeoil ?

Naaa, it's too cheap to be considered as such

The indication that a demagnetizer is working is that the noise level on playback will be lower. This can be as much as 10dB if the head is severely magnetized, and high frequencies can also be partially erased at this level of magnetization. Way down in the weeds, I know.....

 

[Vini darko]

Well someone out bid me anyway

 

[egellings]

I wonder how magnetized tape heads get anyway. The tape sliding past the head has an AC (music, speech) signal on it that should, if anything at all, have a slight demagnetizing effect. Maybe there is input bias current on the tape head preamp causing it?

 

[MakeMineVinyl]

I wonder how magnetized tape heads get anyway. The tape sliding past the head has an AC (music, speech) signal on it that should, if anything at all, have a slight demagnetizing effect. Maybe there is input bias current on the tape head preamp causing it?

Music waveforms tend to be non-symmetrical, and that means there is a DC potential in it which can eventually magnetize the playback head. 2nd harmonic distortion has a DC shift. Having your recorder in 'record' and pulling an RCA cable from the input can put a big surge through the record electronics and magnetize the record head. Erase heads do not typically need demagnetizing because the the erase signal is a pure sine wave, and thus symmetrical.

 

[egellings]

I agree with the idea of music signals being asymmetrical about the X-axis, but what about long term average? I can't think of any other reason why the heads would have a magnetic residue built up in them though, once DC offset bias current is ruled out. Maybe a turn-on thump at power up?

 

[MakeMineVinyl]

I agree with the idea of music signals being asymmetrical about the X-axis, but what about long term average? I can't think of any other reason why the heads would have a magnetic residue built up in them though, once DC offset bias current is ruled out. Maybe a turn-on thump at power up?

The long term average is that playback heads tend to become magnetized over time; this has been my experience in decades of tape machine use. In every studio I've work in, heads are demagnetized daily (capstan shafts and guides occasionally too), along with electronic line-up. Electronics can have something wrong such as a leaky coupling cap to the first preamplification stage allowing DC to backwash to the playback head. Record heads can become magnetized if the coupling cap from the constant current recording amp becomes leaky. If some wayward 'technician' happens to let a magnetized screwdriver near the heads during azimuth adjustments, the heads will almost certainly become magnetized. The solution is easy and cheap - a head demagnetizer.

Once noticeable noise build-up is heard from a magnetized playback head, its already too late because some of the high frequencies have already been partially erased.

 

[Headchef]

Just wondering, is using a demagnetiser not a good idea in the same room as say your speakers or MM/MC cartridge?!?

 

[MakeMineVinyl]

Just wondering, is using a demagnetiser not a good idea in the same room as say your speakers or MM/MC cartridge?!?

There should not be any problem with a head demagnetizer being close to a cartridge (let alone a speaker) as long as the distance is greater than a few inches. Jay McKnight did some research with head demagnetizers and found that 70mm is a safe distance at which there is little or no influence from a demagnetizer. His paper is here.

 

[DVDdoug]

Just wondering, is using a demagnetiser not a good idea in the same room as say your speakers or MM/MC cartridge?!?

It's a very-localized magnetic field. (You should keep it several feet away from your tapes!)

 

[restorer-john]

It's a very-localized magnetic field. (You should keep it several feet away from your tapes!)

And your old skool CRT TV. Works like a mini degausser.

 

[EJ3]

And your old skool CRT TV. Works like a mini degausser.

& Floppy Disks. I once knew a business person that put the 8" floppy with the word processing program on it up against a metal file cabinet and put a magnet on it to hold it there for handy use. That did not work out well for them.

 

[restorer-john]

& Floppy Disks. I once knew a business person that put the 8" floppy with the word processing program on it up against a metal file cabinet and put a magnet on it to hold it there for handy use. That did not work out well for them.

That made me laugh! 8" floppy, ah, the good old days.