It is currently Tue Mar 17, 2020 1:12 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 16 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next
Author Message
Post subject: Pickup tone
Posted: Tue Jun 17, 2014 4:08 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Tue Jul 17, 2007 4:54 am
Posts: 2573
Location: Laurel, MD
I know that you can magnetize a piece of metal, but it will lose that magnetism over time as magetic fields realign within the molicules. I'm not an expert on magnetism, so I'm not sure how it all works.

So does that mean old pickups will die over time or change tonal qualities?


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 4:40 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Sep 14, 2009 7:26 am
Posts: 616
Hi Paris

Its an interesting question with equally interesting answers. There are many variables involved and if the permanent magnets in pickups change in strength over time then yes a coresponding subtle change in tone may result although the strength of the magnets are just a relatively small part "of the overall" reason for an electric guitars sound.

The following is a snippet of info off the net concerning this question.

"A permanent magnet has a permanent orientation of the magnetic moments in a specific vectorially additive direction depending on small crystal domains. To change, i.e. be demagnetized, the magnetic moments have to be randomized by either an external magnetic field or excess heat/melting or vibrations possibly. If nothing like that happens it should be stable. Little magnets in a box left undisturbed would not change magnetisation unless a random magnetic field was in the area ."

and .....

"Some magnets, e.g. AlNiCo, require a keeper (essentially, a piece of iron placed between the poles) to keep magnetic flux lines concentrated inside the magnet, to keep from spontaneously demagnetizing (the material reaches an unstable point in the intrinsic B-H curve). They can also be demagnetized by mechanical means (e.g., by being dropped). I think this is because the shock provides energy necessary to change domain boundaries."

Plenty more where this came from i imagine.....

..Al


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 5:21 am
Offline
Aspiring Musician
Aspiring Musician

Joined: Fri Mar 16, 2012 12:49 pm
Posts: 838
Al 87 wrote:
... There are many variables involved and if the permanent magnets in pickups change in strength over time then yes a coresponding subtle change in tone may result although the strength of the magnets are just a relatively small part "of the overall" reason for an electric guitars sound. ...
I know very little about magnets and even less about magnetic fields but the topic is most interesting. I wonder if a set of pickups can be compared to a good bottle of wine that gets better over time as it ages?

Cheers!
BM

_________________
This is the Blues. Are you listening?


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 8:57 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Fri Sep 05, 2008 6:01 pm
Posts: 1479
Location: Los Angeles, USA
I remember from my college days in EE and physics class we were able to demagnetize by presenting it with a hammer blow and re-magnetize by wrapping it with insulated wire and applying a DC voltage with decent current for a split second. (I was told this re-aligns the electrons that the hammer blow messed up)

But from what I know if not struck with a blow or tampered with electrically, other strong magnetic fields or extreme heat a permanent magnet should last for 1000's of years, possibly millions or even potentially forever... so I have been told. I know there are plenty of old strats and teles from the 50s that the pups still work fine so in all but extreme cases it is probably a non issue. I was never presented personally with evidence if any old guitars sound gets better and/or changes with age like a fine wine but I am sure some would claim this happens. Especially someone with a vested interest in old guitars.

Most likely they would claim this is from the paint/wood "breathing" or something like that over claiming the pickups have changed characteristics over time but who knows?..we hear some new claims every day. 8)

Remember though that a magnetic field is not some kind of magical free "energy" like a battery that would never die over time. A magnetic field is more like a "virtual" spring and until broken with a moving conductor is doing potentially nothing.

_________________
I'm almost out of stuff to sell.


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 9:38 am
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jan 12, 2009 4:50 pm
Posts: 7998
Location: ʎɹʇunoɔ ǝsoɹ pןıʍ
Long answer:

The strings vibrating over the magnet poles create a changing magnetic field. This changing magnetic field is what induces electric current within the windings to create the signal. Simple grade school Physics. It also has a side effect of slowly demagnetizing the poles over years and years of playing. Any magnet exposed to a changing magnetic field will have it's magnetism level affected. How much depends on the magnitude of the changing field and the duration of the exposure. The tiny steel wire cores in guitar strings have very little relative mass and as such produce a relatively low level of changing field.

Short answer:

Yes pickup magnets do fade over time.

_________________
Image
Just think of how awesome a guitar player you could have been by now if you had only spent the last 10 years practicing instead of obsessing over pickups and roasted maple necks.


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 10:00 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
BMW-KTM wrote:
Long answer:

The strings vibrating over the magnet poles create a changing magnetic field. This changing magnetic field is what induces electric current within the windings to create the signal. Simple grade school Physics. It also has a side effect of slowly demagnetizing the poles over years and years of playing. Any magnet exposed to a changing magnetic field will have it's magnetism level affected. How much depends on the magnitude of the changing field and the duration of the exposure. The tiny steel wire cores in guitar strings have very little relative mass and as such produce a relatively low level of changing field.

Short answer:

Yes pickup magnets do fade over time.


+1

The same phenomenon occurs with loudspeakers powered by a rare-earth (ie: alnico) motor. However this degradation of an aging speaker can be reversed by re-charging the magnet, a service that some (but not all) repair shops provide.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 10:08 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Fri Sep 05, 2008 6:01 pm
Posts: 1479
Location: Los Angeles, USA
Pickup magnet manufacturers "claim" a loss of strength at a rate of aprox .2-2% / 100yrs. So I guess if anyone is alive after playing the same pups in a guitar for a few hundred years and have real sensitive ears they might notice a slight mellowing of tone or decreased output.

But of course this is not taking into account the same type and quality of all magnets used or other circumstances that would cause premature loss of strength enough to have a noticeable audible effect. I for one have never seen this but also never had an electric guitar with pups older then 1972ish.

At the risk of getting too technical, the human ear can barely notice a 1db change. It takes a halving of power output to lose 3db. So essentially a change of a few points of a percent or even a few percent for that matter over the course of a hundred years or more is again IMO...a non issue. It could possibly be if the guitar is handed down through many generations although like evolution no one is going to notice such a gradual change. But of course if you could play the guitar one minute and then the next minute the magnet lost 50% of its strength it stands to reason the average human would notice a difference at least in output due to the 3db drop. And that is assuming the strength of the magnetic field effect output decreases the db level in the same logarithmic manner as normal analog audio output such as with a loud speaker or microphone. That I can not confirm...simply theorizing.

_________________
I'm almost out of stuff to sell.


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 6:12 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Jul 17, 2007 9:44 am
Posts: 7282
Location: Washington
I am not a bit worried about my 40 or 50 year old polepieces losing their magnetism.

Of course I don't hit them with hammers or heat them in a blast furnace or use them in powerful magnetic fields.

So as long as we have no EMP from atomic blasts, I am unconcerned.

_________________
Member #26797
My other guitar is a Strat.

Image


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 6:30 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
orvilleowner wrote:
So as long as we have no EMP from atomic blasts, I am unconcerned.


+1

And even if we do, you can protect your pickups by wrapping them in a spare tin-foil hat.

:wink:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 6:45 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Jul 17, 2007 9:44 am
Posts: 7282
Location: Washington
I need a lead box big enough for my guitars and me (to be safe).

_________________
Member #26797
My other guitar is a Strat.

Image


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 7:43 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Fri Sep 05, 2008 6:01 pm
Posts: 1479
Location: Los Angeles, USA
I figure in the worst possible case my pups magnets could lose up to half its strength in 2500 years. If I am still alive then and playing I will post back to let anyone know if I hear a tonal difference. :lol:

_________________
I'm almost out of stuff to sell.


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 8:36 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
orvilleowner wrote:
I need a lead box big enough for my guitars and me (to be safe).


Move to Hanford -- they prolly got something like that big enough there.

:lol:

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 8:46 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Mon Jun 30, 2008 2:52 am
Posts: 3840
Location: Colorado Springs
ebaysux wrote:
Pickup magnet manufacturers "claim" a loss of strength at a rate of aprox .2-2% / 100yrs.

I am assuming that is for Alnico. Is that also true for ceramic magnets, too?

_________________
Laughing out loud with fear and hope, I have a desperate plan ...


Top
Profile
Post subject: Re: Pickup tone
Posted: Tue Jun 17, 2014 9:08 pm
Offline
Professional Musician
Professional Musician

Joined: Tue Sep 11, 2012 2:14 pm
Posts: 2561
Any reduction to the strength of the magnetic field due to the Poles degrading w/ Time is going to be Linear.

This means that Gain & Volume will be more affected than Tone (which is also dependent upon the windings).

Even this degradation will be so slight as to be unnoticable... you'll likely unconsciously increase your attack to compensate and never realize a difference.

It may even be that different brands of strings (with differing Ferrous compositions) will cause a greater change than any weakening of the Pole strength.

cheers!

_________________
Image

'11 FSR Am. Vtg. Ltd. Ed. CAR '57 Stratocaster (SN# LE02639)
'14 American Deluxe Ash Stratocaster
'12 Telebration Empress Telecaster
'99 Deluxe Nashville Telecaster
'12 FSR Telecaster HH
'10 Heritage H-535
'99 Martin DC-1E
'13 Lanikai Tenor Ukulele


Top
Profile
Post subject: Re: Pickup tone
Posted: Wed Jun 18, 2014 3:46 am
Offline
Aspiring Musician
Aspiring Musician

Joined: Sat Apr 20, 2013 12:22 pm
Posts: 718
If for some reason your pole pieces lost their magnetism you can simply re-magnetize them with another strong magnet. Pole pieces are shipped un-magnetized when you order them from StewMac, you have “charge” them after the Bobbin is assembled. 8)

_________________
You can't have too many guitars!


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 16 posts ]  Go to page 1, 2  Next
Go to page 1, 2  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: Google [Bot] and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: