demagnetizing (mr. feedback question)

Fred,
thanx for the hint.

jumping thread: :up:...:)

Eric, Frank and all,
not shure if there is a need for cartridge demagnetizers, AKA fluxbusters AKA exorcists.

I own such a device, avoid for MM cartridges :no:.. a must for MC cartridges :yes:...
My thingie comes from audioquest and once was sold for about US$200 over here. Inside a sloppy oscillator made from 2 BJTs and some passive parts.

i looked at the signal with a high-end DSO: the wave is way from being a sine wave and its decay is way from approaching zero X axis asymptotically.
It does a rough job, but the effect already is amazing.

Now i am happy to have bought that rip-off: None reported so far the thingie fries delicate MC cartridge coils. I asked for that on other forums. It is safe. Now i can measure the output resistance and voltage swing and build a proper working thing: an oscillator or signal generator fed into an opamp circuit working as OTA or multiplying opamp. One input is the constant amplitude sine wave, the other one is the decaying voltage of an RC combination. And the output opamp has a series resistor ensuring no cartridge is fried.

No idea when i am going to build that, therefore i am describing the layout here, but when i do, i post details and schematics in the analogue board.

In the meantime you folks can tell me
what different uses the Exorcist/Purist CDs has. Eager to learn new snake oil tricks :). I always wanted to toy around with that, but so far it was too much tweaking, audio enlightenment level 2, peripheral toying around with spikes and cables :)
 

fdegrove

diyAudio Senior Member
2002-08-21 1:20 am
Belgium
Accessories.

All concerned,


Some guys swear by that stuff here at a Belgian audioforum,claiming some miraculous cures even J.C. would have had a hard time with.
Most offer a CD with signals on,Densen claims to have a CD that actually demagnetizes components,mysteriously.

Bernhard,

The Densen stuff, and all the other companies don't really deal whith that I think,that's real snake oil stuff to me but hey, if it works,why not right?
(Although I hear Densen had a tool called Demagic,I don't think they're still selling it.)
You're talking about recharging cartridge magnets (in particular MC's).
Here I can see an analogy whith LS magnets (not the field coils of course).
Jan Allaerts offers this as a service to custumers,how he does it I don't really know but it must be something along the same lines that you describe.
So far I never felt the need for it but I may just as well ask him to perform the service seeing he still ows me big time.
I remember that AQ thingie though,but pricey no?

Rgds,:)
No idea when i am going to build that, therefore i am describing the layout here, but when i do, i post details and schematics in the analogue board.

Why not?If it's not too hard to make.

Another vinyljunkie's treasure.

Rgds,:)
 
Purist Audio CD

A series of tone burst, weighted noise, noise burst ect. This is used for break in and system tuning. I have used it t for breaking in equipment before shipping it out. I even broke in digital cables in the analog domain with it. The most useful breakin device bar none. Really weird sounds some of which sound like exagerated versions of colorations that hear in unbroken in speakers. Leave the room while using of speakers. Oh remove your cat while doing using the Purist CD or it will never be the same and cannot be trusted around people ever again.

I am quite sure that it could induce epileptic seizures in those prone to them. (I actually had this happen with a epileptic reviewer evaluating some digital audio interface devices-with music though.) I resisted the temptation to say "Wait till you hear this you will have a fit" in my advertising though. I am very fond of this person and hope they never read this. I even forgave them for starting a review of my first product with a verse about me to be sung to the tune of the theme song for the Beverly Hillbillies. I was lot calmer person in those days and it was a great review after all....... My friends and a few dealers tweaked me big time though!

Jim Aud of Purist Audio is probably THE TWEAKIEST guy I have ever met and a major contributor to my esoteric Audio education. Oh he is also a former nuclear power engineer and outstanding material scientist. The only guy I know who designs wire with both subjective and rigorous engineering theory. He was doing Cryogenic treatment long beforn anyone in the audio business. He subcontracts to NASA or a vendor that NASA uses I am not sure which. He designed the solder and metalurgy for much of the wire he uses in his cables. One of the few guys I will call a Guru and keep an absolutey straight face while doing so. Oh ya... I have heard a system with over $30,OOO worth of his wire in it. Programable geometry $10,000 speaker wires with 99 possible configurations anyone? I asked him what possessed him to do this and he very calmly (with a Mona Lisa understated smile) said "that one kind of got away from me." Tweaky enough for you guys?

Fred
 
dice45 said:
Eric, Frank and all,
not shure if there is a need for cartridge demagnetizers, AKA fluxbusters AKA exorcists.

I own such a device, avoid for MM cartridges :no:.. a must for MC cartridges :yes:...
My thingie comes from audioquest and once was sold for about US$200 over here. Inside a sloppy oscillator made from 2 BJTs and some passive parts.

Excuse me Bernhard, demagnetizing a device containing a permanent magnet??? Is this wise? What is the purpose really?
 

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Originally posted by peranders Excuse me Bernhard, demagnetizing a device containing a permanent magnet??? Is this wise? What is the purpose really?

Peranders,
for MM cartridges this demagnetizing is slowly killing the tinytiny moving magnet's magnetisation.
One use already can eat up about 30% output voltage. :Ouch:

MC cartridge:
##OT##
warning: Neverever get close to your MC cartridge's magnet with a ferro magnetic piece of metal I did so once, i was unsure if suspension had gone mushy and the cartridge had enough spacing left to to record surface and used a drill bit of known diameter ... click! :yikes:..the cartridge's SaCo magnet had ripped the drill bit out of my fingers in 2" / 5cm distance :gasp: , lucky me, it did not hit the cantilever. But it was hard if not impossible to remove and removal it self was endangering the cantilever.
##/OT##

I am telling this story to illustrate what beasts of magnets the MC cartridges have.
The SaCo or Nd magnet will just laugh at the tinytiny AC magnet field which the tinytiny 5-20turns coil is fervently trying to emboss on the huge'n'strong magnet.

But there are soft-iron polepieces and they are meant to conduct magnetic flux but are not meant to keep remanent magnetization and sit huffed in the corner of the hysteresis loop. The AC field the coil embosses on the pole pieces is obvioulsy strong enough to bring the pole pieces back to their intended magnetic operating point.
This sitting huffed into the corner is clearly audible, as well as its removal.
Once, i had about 1200 hours of play on my fancy Supex1000 vdHul rebuild, the cartridge lost its fancy sonics with 6 hours of play, except the incredible, *speed of light*-fast low end, all magic was gone, the cartridge sounded distorted, the µµdynamics --just amazing before-- were simply absent. I knew the symptoms, it had been described to me often enough by wealthy cartridgede collectors. I was mourning :sad:, i thot, my beloved thingie had reached EOL, ok, i thot, :RIP: but stay in my drawer as yet another sample for housing dimensions, coils DCR and so on.
Ys later i got this fluxbuster and tried it on the Supex., bingo!! :lifesavr:..µµdynamics back and tone colour saturation and macrodynamics/transients better than ever.:cloud9:

I collected more than one MC cartridge from no-longer-satisfied customers for free, they firmly believed that cartridge arrived at EOL. At home i fluxbustered the cartridge .... :cloud9:

One thing, i avoid prophylactic use, i only use this flux-buster when sonics are going to become a mess.
 

fdegrove

diyAudio Senior Member
2002-08-21 1:20 am
Belgium
DEMAG

Eric,

I heard of stuff like that in professional applications for musicians and recording studios.
Although still considered a bit esoteric in those circles as well.

Maybe you can contact Densen since they had exactly what you are looking for.
The product was called "Demag",I have no personal experience with it but may find you someone willing to sell one.
They're not manufacturing it anymore for reasons I can only guess at but the knowledge should still be in house.

Have a look at :

http://www.densen.dk/

Cheers,

:)
 
Eric and all,

Fred will know, Steve Eddy also should know .... i would be terribly surprised, if ungapped (= avoid DC) coupling trannies would not benefit from demagnetizing and fluxbustering. Would spoil my whole image of what magnetic circuits loathe and like.

And i would expect that even SE OPTs benefit from it.
(transformer experts, correct me if i am wrong), an ideal transformer is not expected to sport any remanence in its core, right? The core transports the magnetic flux generated by the coils, right? It is not meant to generate own flux by remanence effects, right? Just in real life it does.

In my library i discovered a book on magnetic circuits i have forgotten. At the moment it just shows me what dummy i am, concerning magnetic circuits, what i do not yet know, but one thing i already dug out: the higher the core quality i.e. the higher initial permeability of the core, the more any magnetic bias, any DC loading hurts. The more bias, the lower the incremental permeability (sort of magnetic transconductance)

The least i would expect in a signal transformer is sheet metal used for mains transformer cores (which is the most bias insensitive core material). Signal transformers should have core material with high initial permeability. So magnetic bias and remanence should hurt any signal trannie badly.
 

fdegrove

diyAudio Senior Member
2002-08-21 1:20 am
Belgium
Magnetism.

Bernhard,

A pile of books on transformers,chokes,you name it here.
Most of the stuff is 50 years old.
The only thing I know for sure is that the whole thing is a MAJOR
balancing act.
Oh,yes they do get magnetized over time,not much but still enough to upset your delicate hearing.
Fluxblusting the lot is a good idea IMHO.

Hope to hear from Densen but if you have other idea I'd love to hear them,as would Eric I presume.

Ciao,:)
 
Bernard, yes I know that signal transformer cores are likely to become magnetised easily, and damaging sound, especially in pro environment with phantom powering applications.
Hey I might even make my SM-58's sound half decent !.

Frank, thanks. My ex-missus is in Denmark with my boys for the next 12 months, so if we don't do any good I might send her around to sort them out. ;)

Eric.