Demagnetising... is it really needed.

[Smithers XKR]

I have read a lot on the subject and with my very limited knowledge my thoughts are thus...

In a professional recording studio or professional video environment then yes. The equipment is used a lot and serviced by trained audio and video engineers.

But for us average Joes with a home recording facility then the dark art of demagnitising is not really needed and should not be attempted and could actually do more harm then good.
The VCR system actually self cancels magnetism when it runs tapes, I have read.
As far as cassette decks are concerned, then yes the heads can become magnetised ... but under normal playback and home use then it will never pose a major problem and better to leave it than attempt to do it without seeking pro advice.
My learning is yes, clean the heads manually with Iso and a lint free cloth and avoid the head tape cleaners which are abrasive and will only damage the heads. But any demagnetising process is risky and mostly not needed for home use and best left to the professionals IMVHO

 

[rob aylestone]

Demagnetisation is 100% absolutely required if you own any device recording to magnetic media that creates significant magnetisation. Reel to reel and cassette machines that get used a few times month might take several years to get magnetised. Many home recordist spend more time in their studios than a pro studio now. Perhaps not back then.

Demagnetising is NOT and art, it's a practical skill, considered essential by those who value the quality of recordings - which is enthusiasts too. Indeed - magnetised heads can also degrade every recording that goes past them! I had my first demagnetiser in 1976 - I'm currently looking for a replacement. It takes 30 seconds and is very simple to do, totally safely. It's really not complicated or risky. Place very close to, but not touching the head gap. Switch on, slowly withdraw and when you are 2m or so away, switch off. Repeat for every head, and for completeness, any other metal parts in the tape path that could be magnetised if there are any. Job done.

It's like changing the car oil, but not doing the filter - half a job.

 

[Smithers XKR]

Demagnetisation is 100% absolutely required if you own any device recording to magnetic media that creates significant magnetisation. Reel to reel and cassette machines that get used a few times month might take several years to get magnetised. Many home recordist spend more time in their studios than a pro studio now. Perhaps not back then.

Demagnetising is NOT and art, it's a practical skill, considered essential by those who value the quality of recordings - which is enthusiasts too. Indeed - magnetised heads can also degrade every recording that goes past them! I had my first demagnetiser in 1976 - I'm currently looking for a replacement. It takes 30 seconds and is very simple to do, totally safely. It's really not complicated or risky. Place very close to, but not touching the head gap. Switch on, slowly withdraw and when you are 2m or so away, switch off. Repeat for every head, and for completeness, any other metal parts in the tape path that could be magnetised if there are any. Job done.

It's like changing the car oil, but not doing the filter - half a job.

Thanks Rob Just ordered one off ebay. The car analogy struck a chord as I look after my old Jag obsessively.
Cheers

 

[Smithers XKR]

Demagnetisation is 100% absolutely required if you own any device recording to magnetic media that creates significant magnetisation. Reel to reel and cassette machines that get used a few times month might take several years to get magnetised. Many home recordist spend more time in their studios than a pro studio now. Perhaps not back then.

Demagnetising is NOT and art, it's a practical skill, considered essential by those who value the quality of recordings - which is enthusiasts too. Indeed - magnetised heads can also degrade every recording that goes past them! I had my first demagnetiser in 1976 - I'm currently looking for a replacement. It takes 30 seconds and is very simple to do, totally safely. It's really not complicated or risky. Place very close to, but not touching the head gap. Switch on, slowly withdraw and when you are 2m or so away, switch off. Repeat for every head, and for completeness, any other metal parts in the tape path that could be magnetised if there are any. Job done.

It's like changing the car oil, but not doing the filter - half a job.

PS.... I have just come across this article about DCC which warns of the dangers of demag a digital tape machine. I think I will just stick with your advice to use the demagnetizer for the twin deck analogue cassette plus the VCR and the Yamaha Multitracker for now... and leave the DCC and ADATs until I get a better idea of what is going on.
I know you said you like to blow away fake news on the web and that is good.... respect for you , it may be garbage wrong info.... but... I will just err on the safe side for now.
Its all a blooming minefield at the mo for me Rob
Thanks mate

Forgotten audio formats: Digital compact cassette

A story of digitalization, Britpop, naughty ads, and, ultimately, better beer.

arstechnica.com

 

[Smithers XKR]

Demagnetisation is 100% absolutely required if you own any device recording to magnetic media that creates significant magnetisation. Reel to reel and cassette machines that get used a few times month might take several years to get magnetised. Many home recordist spend more time in their studios than a pro studio now. Perhaps not back then.

Demagnetising is NOT and art, it's a practical skill, considered essential by those who value the quality of recordings - which is enthusiasts too. Indeed - magnetised heads can also degrade every recording that goes past them! I had my first demagnetiser in 1976 - I'm currently looking for a replacement. It takes 30 seconds and is very simple to do, totally safely. It's really not complicated or risky. Place very close to, but not touching the head gap. Switch on, slowly withdraw and when you are 2m or so away, switch off. Repeat for every head, and for completeness, any other metal parts in the tape path that could be magnetised if there are any. Job done.

It's like changing the car oil, but not doing the filter - half a job.

PPS - the paragraph isnt very clear. It just says that "DCC heads never need to be demagnetised and using a head demagnetiser tape could actually write them off".
Now I presume that it meant using analogue cleaner/demag tape would screw the heads. It doesnt actually say that you cant use a demag tool.
After good advice from you guys here, I would now NEVER use a cleaning tape on any magnetic media heads.
Dedicated DCC cleaning tapes were available but no longer in production, so I am still in the dark.
My apologies for keep banging on about this issue and query Rob, just trying to get some clarification, it really appreciated mate

 

[jamesperrett]

I think the digital part of the DCC heads uses a special head design that can be damaged by a demagnetiser. Probably best not to use one on it.

I have only encountered an obviously magnetised head on one occasion but I still demagnetise my machines from time to time as a precaution. One of the major causes of magnetisation is experiencing a power cut while in record. Normally the bias and erase signals should reduce gradually when a machine comes out of record but if the power is interrupted this gradual decay may not happen, leaving the head magnetised.

 

[Smithers XKR]

I think the digital part of the DCC heads uses a special head design that can be damaged by a demagnetiser. Probably best not to use one on it.

I have only encountered an obviously magnetised head on one occasion but I still demagnetise my machines from time to time as a precaution. One of the major causes of magnetisation is experiencing a power cut while in record. Normally the bias and erase signals should reduce gradually when a machine comes out of record but if the power is interrupted this gradual decay may not happen, leaving the head magnetised.

Thanks James

 

[Smithers XKR]

I think the digital part of the DCC heads uses a special head design that can be damaged by a demagnetiser. Probably best not to use one on it.

I have only encountered an obviously magnetised head on one occasion but I still demagnetise my machines from time to time as a precaution. One of the major causes of magnetisation is experiencing a power cut while in record. Normally the bias and erase signals should reduce gradually when a machine comes out of record but if the power is interrupted this gradual decay may not happen, leaving the head magnetised.

Do you think this also would apply to the ADAT machines? Should I just stick to using the demagnetizer on the analogue machines and VHS?
Thanks

 

[jpmorris]

ADAT machines are basically off-the-shelf S-VHS decks, so a demagnetiser that works on a VHS machine should presumably work on an ADAT machine. AFAIK all they did was add new encoding/decoding circuitry on top of the video processing system. Though I must admit, I have no clue how you'd allow for overdubbing in such a system.

DCC on the other hand had 18 tracks packed into a 1/8" head - apparently the digital heads were literally produced via lithography like a microchip, so yes - I suspect a degausser for a tape deck would probably melt them.

 

[Smithers XKR]

ADAT machines are basically off-the-shelf S-VHS decks, so a demagnetiser that works on a VHS machine should presumably work on an ADAT machine. AFAIK all they did was add new encoding/decoding circuitry on top of the video processing system. Though I must admit, I have no clue how you'd allow for overdubbing in such a system.

DCC on the other hand had 18 tracks packed into a 1/8" head - apparently the digital heads were literally produced via lithography like a microchip, so yes - I suspect a degausser for a tape deck would probably melt them.

Thanks JP yes the ADAT is a SVHS mech, so will go down that route. You are quite right about DCC, the information I have from the DCC museum on the web is basically the format is a compressed version of the Phillips SVHS video system and although you can play standard analogue tapes on a DCC it is not recommended. In which case .... why did they include that facility in the bloody first place ???!! Bah!

Thanks JP

 

[rob aylestone]

Oddly, demagnetising video and very narrow track heads is less critical, because the heads are so small their design is quite different. With reel to reel and cassette heads the design features considerable amounts of metal, wrapped around, with the very precise gap where the actual magnetism is focussed. The higher levels make magnetising these head components a normal process, that needs fixing, in video, DAT and computer backup style heads, the design is quite different, and is often a tiny coil of wire, with just a few turns making a coil mounted on a bead of non conductive material, which gets ‘wiped’ across the tape. I’m not actually even sure if it’s possible to actually magnetise them? With DCC the heads were small, but fairly conventional appearance, so my guess is magnetisation is possible, but probably less susceptible to it, but the fragility and alignment make the recommendation to not poke a demagnetiser core into them, as damage is pretty likely. I suppose they had a think and decided the risk outweighed the benefit. With cassette and reel to reel its the other way around. It’s just part of routine servicing. It might also be a simple result of a digital waveform. As it changes polarity at such a high frequency maybe a digital data stream IS a demagnetising function? Never thought about that one. Does a digital signal even make magnetisation a possibility? Analogue, being AM does do this, but an FM recording system applies continuous current that continuously reverse polarity. Lots to think about?

 

[jpmorris]

Oddly, demagnetising video and very narrow track heads is less critical, because the heads are so small their design is quite different. With reel to reel and cassette heads the design features considerable amounts of metal, wrapped around, with the very precise gap where the actual magnetism is focussed. The higher levels make magnetising these head components a normal process, that needs fixing, in video, DAT and computer backup style heads, the design is quite different, and is often a tiny coil of wire, with just a few turns making a coil mounted on a bead of non conductive material, which gets ‘wiped’ across the tape. I’m not actually even sure if it’s possible to actually magnetise them?

Yes, I can't honestly say I remember hearing about demagnetising video decks. With DCC the heads supposedly have two designs, the digital ones being coils that can't be magnetised, as you point out. The analogue heads are conventional, but can't really be demagnetised as doing so is liable to wreck the digital ones.

 

[jamesperrett]

Do you think this also would apply to the ADAT machines? Should I just stick to using the demagnetizer on the analogue machines and VHS?
Thanks

I'd just use the demagnetiser on analogue machines. I certainly wouldn't try to demagnetise video heads or anything similar to a video head.

 

[Smithers XKR]

I'd just use the demagnetiser on analogue machines. I certainly wouldn't try to demagnetise video heads or anything similar to a video head.

That's what I maybe thought, thanks James. I found out that the ADAT's and VCR use Aluminium rotating drum heads and the DCC fixed Al heads. So its pointless and could damage them. The only components in these machines mechanism which could be magnetised are the steel pinch rollers. I will stick to deguassing the ferric based head analog machines.
Cheers

 

[Smithers XKR]

That's what I maybe thought, thanks James. I found out that the ADAT's and VCR use Aluminium rotating drum heads and the DCC fixed Al heads. So its pointless and could damage them. The only components in these machines mechanism which could be magnetised are the steel pinch rollers. I will stick to deguassing the ferric based head analog machines.
Cheers

Capstan's not PR's ..
Doh!

 

[rob aylestone]

I've been struggling to remember which make and model it was, but I'm sure there was one 70s reel to reel that had a design flaw in that if you used the selector switches to drop out of recording, rather than pressing stop, there was a good chance of magnetising it badly. It might have been an Akai or a Sony - I just can't remember. I think it was discussed in the magazines of the time - the bias current, if switched off at the top of the cycle, left the head magnetised. Pressing stop - the usual way, let the current ramp down quickly with no magnetism induced.

 

[Smithers XKR]

I've been struggling to remember which make and model it was, but I'm sure there was one 70s reel to reel that had a design flaw in that if you used the selector switches to drop out of recording, rather than pressing stop, there was a good chance of magnetising it badly. It might have been an Akai or a Sony - I just can't remember. I think it was discussed in the magazines of the time - the bias current, if switched off at the top of the cycle, left the head magnetised. Pressing stop - the usual way, let the current ramp down quickly with no magnetism induced.

To me Rob, people say that old tech is a waste of time but there is something more than that. It is more tactile and overcoming the problems of old tech is kind of cathartic and theraputic in a way and gives a little sense of achievement. I want to do all this and get my legacy stuff nailed down and learned from A to Z and also learn DAW.

Sorry if that sound like a load of twaddle

 

[rob aylestone]

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.

 

[Smithers XKR]

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.

I get your point Rob and I suppose right now it is slightly until I get it all learned sorted.... but .... I know my way around an old Atari and Cubase 3 on floppy, so the legacy gear that I know does not affect my songwriting using that old gear at all.

But I do take your point. I do not think it will take me any more effort to learn to use the outboard legacy gear I have than to get up to speed with DAW. Yes .... more technical hardware issues I may come across but certainly no more learning I believe.
So... respectfully... there's your answer
Cheers

 

[Smithers XKR]

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.

Thats why I am on a learning journey to learn all of the legacy gear I have and also to learn about DAW as well. It will take a long time but that is the fun and rewarding enjoyment of it all. My humble opinion is that they are not exclusive and can be both used in the creative process... just ask Lenny Kravitz