AudioNervosa

Specialists => Audiologists => Topic started by: dflee on August 09, 2018, 10:15:55 AM

Title: Demagnetizing
Post by: dflee on August 09, 2018, 10:15:55 AM
Guys, I know there is a topic here discussing demagnetizers but can't locate it.
Just got a Furutech RD2 for cheap and want to know what y'all think.

Thanks
Don
Title: Re: Demagnetizing
Post by: Nick B on August 09, 2018, 12:13:29 PM
Not much time right now, but I did a quick search under ...... demagnetizing. That’ll bring up a few things
Nick
Title: Re: Demagnetizing
Post by: steve on August 09, 2018, 03:21:44 PM
This is an interesting subject, Dflee. Interestingly, when vacuum tubes are manufactured, one of the last processes is  induction high temperature heating of the internal metals.

The question I have is how the electric field is removed, slowly or instantaneously. Instantaneously would mean  magnetizing of the internal metal structure.

Has anyone else demagnetized their vacuum tubes, and if so, were there any perceived sonic differences?

cheers

steve
Title: Re: Demagnetizing
Post by: tmazz on August 09, 2018, 04:34:18 PM
I have used a Bedini Ultra Clarifier unit, which is conceptually similar to the RD2 for many years and have always liked the results.

Here is a link to the Six Moons review of the RD2:

http://www.6moons.com/audioreviews/furutech/rd2.html
Title: Re: Demagnetizing
Post by: rollo on August 13, 2018, 11:55:49 AM
Steve I will try a bulk tape eraser on some tubes and let you know outcome.

charles
Title: Re: Demagnetizing
Post by: tmazz on August 13, 2018, 04:37:41 PM
That Furutech unit is meant for demagnetizing CDs. I'm not sure how we got onto doing tubes.

Anyway, is this the type of Bulk eraser you are talking about using?

(https://thumbs.worthpoint.com/zoom/images1/1/0711/14/vtg-realistic-bulk-tape-eraser_1_b90c38af0065407a731437c1241d8db4.jpg)

If so I would be very careful using it on tubes. These units produce a very strong magnetic field. I would be worried that it is strong enoughto pull on theplates and perhaps move them in such a way that would damage the tube  or perhaps bend then to such an extend that the movement is permanent and the new relative locations of the plates could change the operating characteristics of the tube. If you pulled them hard enough you could even cause them to touch causing a dead short withing the tube that could cause significant damage to your amp.

Caution would be the word of the day.
Title: Re: Demagnetizing
Post by: rollo on August 14, 2018, 08:28:45 AM
 Yes. That is the one. Thanks for the advice.


charles
Title: Re: Demagnetizing
Post by: P.I. on August 14, 2018, 04:32:15 PM
+ 1 on being very careful.  Remember that these demagnetizers were made to bulk erase a pound of material or so at a time.  The field is strong.  Anyone that used one knows how they can shake while demagging a roll of 2" tape.

I would recommend getting no closer to the tube than 6" and then pull the tube away from there.  You have to "pull away" to not leave a residual magnetic field on the tube.

I believe tubes will create their own magnetic orientation during operation, but think it would be a very good thing to begin from zero base as far as magnetization is concerned.

I'll try it.

I know that cryo is a good thing for tubes and think it would be a very good thing to demagnetize tubes before cryo treatment.

I love this place.  It makes me think  :thumb:

<><

Dave
Title: Re: Demagnetizing
Post by: steve on October 14, 2018, 06:33:25 PM
Yes. That is the one. Thanks for the advice.

charles

Charles, were you able to come to any findings concerning demagetizing tubes etc?

cheers

steve
Title: Re: Demagnetizing
Post by: rollo on October 15, 2018, 08:40:39 AM
Yes. That is the one. Thanks for the advice.

charles

Charles, were you able to come to any findings concerning demagetizing tubes etc?

cheers

steve


   Not yet just too busy lately. As far as Furutech unit is concerned a winner in every respect. Yes I sell them.

charles
Title: Re: Demagnetizing
Post by: rollo on October 17, 2018, 09:43:41 AM
  Noticed ZERO difference. Had a HUGE difference however after ridding the static electricity from system. Who knew ???

charles
Title: Re: Demagnetizing
Post by: steve on September 02, 2019, 05:15:45 PM
  Noticed ZERO difference. Had a HUGE difference however after ridding the static electricity from system. Who knew ???

charles

I noticed some difference but then it seemed to disappear over time. Could be because of the repeated high
DC voltage charge magnetizing the plate. I used my large soldering gun next to the tube, no sweat what
so ever since large electromagnetic fields are used when manufacturing the tubes, often heating the plate to
very high temperatures as well as "flashing the getter".

cheers
steve
Title: Re: Demagnetizing
Post by: rollo on May 16, 2020, 12:54:41 PM
Steve I will try a bulk tape eraser on some tubes and let you know outcome.

charles

   YES it makes a difference. I stand corrected. Not as much with new tubes although heard a positive difference. With NOS tubes KABOOM baby.
  Zero noise, more dynamic and more information.


charles
Title: Re: Demagnetizing
Post by: steve on May 17, 2020, 12:50:07 PM
Thank you for your information Charles. Much appreciated.

steve
Title: Re: Demagnetizing
Post by: _Scotty_ on May 17, 2020, 06:26:55 PM
I have used a big Weller gun and a 2 inch coil with maybe 10 turns of 8ga insulated wire from Home Despot in place of the copper solder "tip" to make a deguassing coil. I pass the object to be demagnetized through the coil and presto. You could probably just wave the coil over the piece needing treatment and get the job done.
Scotty
Title: Re: Demagnetizing
Post by: rollo on August 22, 2020, 08:24:02 AM
  So obviously over time we build up magnetism in our components. If we UNPLUG them for several days will not the magnetism wear off ? How long can a piece of metal stay magnetized ?



charles
Title: Re: Demagnetizing
Post by: _Scotty_ on August 22, 2020, 02:03:03 PM
From what I can glean from the scientific literature on magnetism only ferromagnetic materials can be magnetized. They require a constant magnetic field from a permanent magnet or a magnetic field from a constant non-fluctuating DC power source. Brass, copper and other non-magnetic materials will not be readily magnetized by a low level musical signal as is found in the circuitry of small signal devices up stream of a power amp.
I would be very reluctant to attempt to deguass any small signal circuitry due to the possibility of damage due induced currents of greater amperage than the device or circuit was designed to handle. This damage would be analogous to the type of damage seen from EMP which tends to fry things that are not hardened in some way.
As far as how long something might remain magnetized, I have screw drivers that I magnetized with a permanent magnet years ago and they are still magnetized.
Scotty
Title: Re: Demagnetizing
Post by: rollo on August 23, 2020, 08:53:03 AM
  Thanks Scotty.

charles
Title: Re: Demagnetizing
Post by: BobM on August 26, 2020, 07:03:45 AM
There has always been controversy about degaussing phono cartridges for the reasons you state above Scotty. They are delicate instruments with a magnetic field and very small tolerances. The possibility of screwing them up far outweighs any suspected benefits IMO.

As for demagnitizing CD's or vinyl records, I've tried it and heard nothing different. Logically it would make sense that it shouldn't have any effect, but then we all know that logic isn't always correct in audio, and we also know there is a lot of snake oil out there too. YMMV.
Title: Re: Demagnetizing
Post by: P.I. on August 26, 2020, 04:27:40 PM
There has always been controversy about degaussing phono cartridges for the reasons you state above Scotty. They are delicate instruments with a magnetic field and very small tolerances. The possibility of screwing them up far outweighs any suspected benefits IMO.

As for demagnitizing CD's or vinyl records, I've tried it and heard nothing different. Logically it would make sense that it shouldn't have any effect, but then we all know that logic isn't always correct in audio, and we also know there is a lot of snake oil out there too. YMMV.
Stay tuned about the CD thing...