View Full Version : Cartridge Demagnetisers
I'm thinking of getting one. Anyone used them? If so what are the pros and cons? :)
Marco.
I'm suspicious of them Marco, especially if used with moving coil cartridges.
They might be of use if you use a headamp as a step-up device, as there is always the possibility that a small amount of DC may be fed through the coils, but since you use a transformer that will not occur.
I have read of benefits but as I say I'm sceptical.
You won't do any harm, but these demagnetisers are quite expensive - so go on, try one out and let us know your findings.
Regards
You won't do any harm...
I'm also suspicious of them, simply for the above reason. If you reckon they won't do any harm, then I'll probably give one a go... The last thing I'd want, however, was to damage my SPU!
Marco.
prestonchipfryer
24-03-2012, 14:29
Have you seen this?
http://www.youtube.com/watch?v=1TkJ_wwkbNA
Dunno if it works or no. :)
Total aside Marco- is your new avatar in any way related to the now defunct 23rd precinct record shop in glasgow?
Yes, Mike, that's exactly what it is! :)
Interesting video on the demagnetising.... Has anyone tried what's being recommended?
Marco.
That place was great on a Friday afternoon esp- hadn't realised it had shut until I went for a sentimental visit a couple of months ago and the occupier had changed. Bought some great stuff in there. Was it run partly by Michael Kilkie? If so I have very good memories of seeing him play at Aberdeen uni union and him putting on Rapture by Iio.
sq225917
24-03-2012, 18:19
Your cartridge coils are copper or maybe silver or gold or platinum. None of which will become magnetised, so the only thing you could demagnetise are the magnets- and you don't want to do that now do you.
Reid Malenfant
24-03-2012, 18:34
Have you seen this?
http://www.youtube.com/watch?v=1TkJ_wwkbNA
Dunno if it works or no. :)
It'd be a damn sight easier to fit a dpdt (2 pole changeover) switch in the front end of the phono stage & short the cartridge that way, rather than messing about disconnecting stuff :lol:
The method in the video works fine. I have a phono amp that takes RCA plugs for loading so I just have a pair of plugs on hand set up shorted with a piece of wire in place of a loading resistor (ie. 0 ohm load). I think the Esoteric E-03 has a 'demag' setting to do the same thing. Easy enough to try it and see anyway.
ursus262
24-03-2012, 18:53
Your cartridge coils are copper or maybe silver or gold or platinum. None of which will become magnetised, so the only thing you could demagnetise are the magnets- and you don't want to do that now do you.
Well, quite!
It'd be a damn sight easier to fit a dpdt (2 pole changeover) switch in the front end of the phono stage & short the cartridge that way...
Well, it might be, if I knew what the hell that was and how to do it? :scratch: :D ;)
Anyway, is the consensus of opinion on cartridge demagnetising that:
a) It's 100% safe, whether one uses a demagnetiser or the method in the video.
b) It's sonically a worthwhile thing to do.
??
Marco.
ursus262
24-03-2012, 18:59
But surely you'd demagnetise the magnets that move in relation to the coils! Or am I missing something here?
Reid Malenfant
24-03-2012, 19:04
Well, it might be, if I knew what the hell that was and how to do it? :scratch: :D ;)
Anyway, is the consensus of opinion on cartridge demagnetising that:
a) It's 100% safe, whether one uses a demagnetiser or the method in the video.
b) It's sonically a worthwhile thing to do.
??
Marco.
I'll get a diagram knocked up for you schweety :eyebrows:
a) perfectly safe to short out as per the video! I wouldn't stick anything that demagnetises near any cartridge of mine thank you very much :nono:
b) I don't know, but it can't do any harm :cool:
I'll get a diagram knocked up for you schweety :eyebrows:
a) perfectly safe to short out as per the video! I wouldn't stick anything that demagnetises near any cartridge of mine thank you very much :nono:
b) I don't know, but it can't do any harm :cool:
Awesome :cool:
Marco.
As I have said I'm suspicious of cartridge demagnetising - and as others have said what is there in a cartridge that need demagnetising?
The magnets used are sufficiently powerful that the commercial cartridge demagnetisers are not going to have any effect on them.
Regarding the video, which I seem to remember having seen before and commenting on the Forum, the technique shown results in loading one channel of the cartridge by the source impedance of the other and vice versa. So, what we have is one channel behaving as a motor being fed by the other channel acting as a generator and vice versa.
The upshot is the cartridge mechanism is severly damped, not as severe as shorting out each channel, but the effective compliance will be reduced. If any damage is being done, it will be to the record.
Try it out, but use a record you are not worried about.
how much we talking for a cartridge demagnetizer then, more than a furutech demag is it?
Dominic Harper
24-03-2012, 20:27
I wouldn't use one Marco. Have you tried the Cardas sweep record. Prob the only setup, cleaning record I would recommend.
Plus it is supposed to demagnetize your cart no less. Not sure how true that is but an interesting product.
address the other weak points in your system first I suggest...:ner:
how much we talking for a cartridge demagnetizer then, more than a furutech demag is it?
Quite a lot: http://www.ebay.co.uk/sch/i.html?_nkw=cartridge%20demagnetizer&clk_rvr_id=326787967062&keyword=cartridge+demagnetizer&geo_id=32061&crlp=10387717357_2113181&MT_ID=11&tt_encode=raw
how much we talking for a cartridge demagnetizer then, more than a furutech demag is it?
Quite a lot: http://www.ebay.co.uk/sch/i.html?_nkw=cartridge%20demagnetizer&clk_rvr_id=326787967062&keyword=cartridge+demagnetizer&geo_id=32061&crlp=10387717357_2113181&MT_ID=11&tt_encode=raw
One positive review can be read here: http://www.audiophilia.com/hardware/diyttstand.htm
But I'm still sceptical.
address the other weak points in your system first I suggest...:ner:
Are you referring to me, dafty? If so, what would those be? :)
Marco.
Reid Malenfant
24-03-2012, 20:36
Regarding the video, which I seem to remember having seen before and commenting on the Forum, the technique shown results in loading one channel of the cartridge by the source impedance of the other and vice versa. So, what we have is one channel behaving as a motor being fed by the other channel acting as a generator and vice versa.
Are you sure Barry? In a single ended wiring from the record deck to the phono amplifier aren't both grounds connected together at the bottom of the tonearm?
Hmmm, maybe not. I was assuming they may well be & that the output of the cartridge was simply being shorted out :scratch:
Wouldn't it have just about the same effect though...
I wouldn't use one Marco.
Out of curiosity, Dom. Why not?
Marco.
why not just put it on here?
https://encrypted-tbn2.google.com/images?q=tbn:ANd9GcT6i4K8priimgrFyoO4UbU6oMcsy3Rp3 G6nddwaCLkdXGsDEsP0ew
Dominic Harper
24-03-2012, 20:38
I see an awful lot of carts with damaged coils. This is an expensive repair. Would you run the risk of putting a current through those coils?
Dominic Harper
24-03-2012, 20:42
I have no definitive answer on this subject before anyone asks, but I would prefer to err on a more cautious approach.
Are you sure Barry? In a single ended wiring from the record deck to the phono amplifier aren't both grounds connected together at the bottom of the tonearm?
Hmmm, maybe not. I was assuming they may well be & that the output of the cartridge was simply being shorted out :scratch:
Wouldn't it have just about the same effect though...
Most tone arms have 5 conductors in the lead: 2 for each channel (x2) + a ground wire for the arm metal work. But it doesn't alter my argument; you are effectively 'shorting out' the generator, albeit with the source inpedance of the other channel. Some vintage arms may have a three wire arrangement, using a common ground (screen).
Severe loading of a cartridge will affect it's tracking ability. I know from experience, based on experiments I have done with the Decca Mk. V series.
But you are right, it would have just about the same effect.
Reid Malenfant
24-03-2012, 20:52
But you are right, it would have just about the same effect.
That's what I figured, so it could be done a lot easier than unplugging stuff & messing about.
I still can't figure what it's going to do though, I mean I can understand demagnetising a tape head.... But a cartridge? :scratch: :confused:
I see an awful lot of carts with damaged coils. This is an expensive repair. Would you run the risk of putting a current through those coils?
In normal use there is current flowing through the coils: the cartridges are generators, loaded by the preamp. The amount of current varies depending on the type of cartridge:
Fixed coils have a typical output of say 5mV into 50kOhm, that is a current of 0.1uA
Moving coils have a typical output of say 0.2mV into 100Ohm, that is 2uA.
Running the cartridge 'backwards' by putting an external current through the coils, will change the cartridge from being a generator into being a motor.
The important thing is not to put too much current through the coils. It is for this reason that cartridge manufacturers alway warned never to check for coil continuity by using a multimeter: most multimeters have too low an input impedance causing too large a current to flow when on the "Ohms" range.
I have no idea how much current is pushed out by these defluxers, but I would imagine it is sufficiently low so as not to cause damage.
Ammonite Audio
24-03-2012, 23:26
I have a Gryphon cartridge demagnetiser and it definitely has an effect, but not one that I like - musically the sound seems rather damped and suppressed afterwards. Fortunately, the negative effect diminishes quite quickly, but I still don't know if there is any overall benefit, so that probably means there is not.
Mmm... I think that I've gone off the idea now, so if anyone fancies landing a mint demagnetiser, at a bargain price, he's the one I was looking at:
http://www.ebay.co.uk/itm/150781190341?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Can't see it going for much more than £25!
Marco.
Dominic Harper
25-03-2012, 08:06
Mmm... I think that I've gone off the idea now, so if anyone fancies landing a mint demagnetiser, at a bargain price, he's the one I was looking at:
http://www.ebay.co.uk/itm/150781190341?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Can't see it going for much more than £25!
Marco.
I'm glad you've changed your mind Marco. Dom believes there not that good and can damage the cart. Anyway, I wouldn't know because I have never seen them before until you mentioned them and I looked at the video. Surely that can't be a good idea.
Natalie;)
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