Pickup magnets strength

[ehdwuld]

So i have some alnico mags sitting around

I got a compass on my phone to check polarity

But i have no idea if some are a2 or a5 or what

I know the ceramics are that

I used my old phone as a gauss meter some years ago and jacked up a phone

so anyone got a recommendation for an inexpensive gauss meter?
Or some other way to check a2 vs a5 magnets?

also

I think the a5 would be stronger than the a2 , correct?
​​​​​​​I mean noticeably stronger

 

[freefrog]

Reliable gaussmeters could be found for a low price until recently among MIC articles sold online. The WT10A comes to my mind as an example of this (sorry, I don't remember the brand and anyway, I think this model comes under various brand names). It looks cheap but does the job efficiently.

Most often, one can say if a magnet is A2 or A5 by measuring the inductance of the pickup in which they are loaded. With magnets of the same size and mass, A2 will cause a higher measured inductance because it contains more iron.

A5 is normally stronger than A2 if charged in the same way... but I've already measured a vintage RC A5 @ an average value of 314G while an A2 next to it was @ 324G. The only way to identify the vintage A5 as such was... the measured inductance.

I'd keep in mind the variability of AlNi(Co) alloys anyway. Zollner from the GITEC lists no less than 8 kinds of A5 and concludes from this : Obviously, a “typical” Alnico 5 material does not exist. <:O)

FWIW. HTH.

 

[ehdwuld]

thanks for the response

I once asked a coworker what the most common way something was done
and he proceeded to profile several one off instances "well one time i saw...."

thanks anyway

 

[Chistopher]

A very weak test you can do is take a known A5 and known A2 and compare how hard the unknowns are to pull off your refrigerator. A5s are stronger so they stick harder.

This isn't the most robust test if you have magnets other than A2,A5, and ceramic.

 

[beaubrummels]

Short of the above recommendations, a last resort might be to put them in a test pickup you know how it should sound and hear what the difference becomes with those magnets.

 

[ehdwuld]

I appreciate your input

I think a cheap gauss meter as mentioned should sort it out

I have some neo mags that are roughly the size of pickup magnets

I am curious as to what they sound like

I wonder if a gauss meter will determine if the poles of the magnets are face oriented or edge oriented
as you know the pickup magnets have their poles edge to edge
while refrigerator magnets are face to face

this may cause some issues in installing my fridge neos into my humbuckers

maybe not

 

[freefrog]

Short of the above recommendations, a last resort might be to put them in a test pickup you know how it should sound and hear what the difference becomes with those magnets.

+1. The first thing I do when I test AlNi(Co) bars is forgetting what alloy is supposedly involved while opening my ears and my mind.

Reason: I've not that often tested two magnets with exactly the same inductive influence / average flux strenght, except with ceramic. I'd even say that many of them were "one off instances" to try as such...
​

 

[hamerfan]

I appreciate your input

I think a cheap gauss meter as mentioned should sort it out

I have some neo mags that are roughly the size of pickup magnets

I am curious as to what they sound like

I wonder if a gauss meter will determine if the poles of the magnets are face oriented or edge oriented
as you know the pickup magnets have their poles edge to edge
while refrigerator magnets are face to face

this may cause some issues in installing my fridge neos into my humbuckers

maybe not

In the old days before i had a gauss meter i made the fridge test. First i took out the Duncan mags. They are black and blue marked as A5 and A2. Then i lined all others on the edge of the fridge and pull them off at the edge. Some were harder to pull, some easier. Then i compared them to marked Duncans. Then i marked them with permanent sharpie on the North side with a capital N and with name and source as ‚A2 Gibson 490N‘ on the flat side.
Now its easy to work with that stash of all together 32 and 3 big ass neos for recharging.

 

[ehdwuld]

Yeah I'm thinking about guass meter should ease the guess

I have several in the stash and I have tried to mark each one

But some come in with no name pickups that are Alnico, but I haven't a clue as to what the are

 

[ehdwuld]

Dang it
the gauss meter didn't help at all

Wildly high gauss on either magnet

No real difference at all

I thought it would be like 600 T for one but 400 T for the other just not the case at all


Even trying the fridge technique
And no difference could be detected that way either

Maybe they are all just the same and mislabeled

 

[freefrog]

Dang it
the gauss meter didn't help at all

Wildly high gauss on either magnet

No real difference at all

I thought it would be like 600 T for one but 400 T for the other just not the case at all


Even trying the fridge technique
And no difference could be detected that way either

Maybe they are all just the same and mislabeled

Which magnetometer* have you used and how?

In such cases, I do several measurements per bar and calculate their average flux strenght. YMMV.

I would find 600G a bit high BTW: my archived measurements (with various magnetometers) go from 211G for A3 to 650G for A8 but A2 / A4 / A5 tend to stay between these extreme values, with +/- 100G / 10mT of average difference between A2 and A5 bars charged and tested in the same way.

If an A2 and an A5 exhibit similar charges, which is possible, inductance measurements remain a reliable way to recognize which is which (with A2 giving 4.6H vs 4.4H for A5 in a same Gibson style HB, for instance).

This answer was initially much longer: it has been edited out to be less tedious to read.


*The WT10A that I've evoked in the first answer has been compared to other magnetometers here but also on guitarnutz2 by another geeky contributor and both comparisons confirmed this piece of gear as reliable albeit inexpensive.

 

[ehdwuld]

Well i compared the reading I got with my phone
that has the aforementioned gauss meter

And this
https://a.co/d/5K1cTms

The readings were so close as to be non discernable

as you say the Inductance is almost identical as well
it 4.4 and 4.6 is within the deviation of either magnetic pickup

 

[freefrog]

4.4 and 4.6 is within the deviation of either magnetic pickup

According to what I've already tried to share: if two bar magnets of a same size and mass give respectively 4.4H and 4.6H in a same humbucker, the one causing the higher inductance contains more iron and is therefore of a lower grade than the other (except for A3, somehow misnamed since it theoretically gives the highest inductance and weakest magnetism).

if ever it's not true, it's because of differences in mass due to varying size and weight of magnets. In this case, using a precision scale + doing a bit of maths allow to know the inductance to mass ratio and to guess what is the alloy involved.

It's a reliable approach, that I've applied many times. But as a matter of fact, it requires reliable (lab) meters adapted to the task. For what you want(ed) to do, a magnetometer with a Hall effect probe would be required.

 

[ehdwuld]

Yeah sounds that way

The gauss is close
the Inductance is close
the sound of a pickup with either one isn't dramatically different

makes it seem as though there is a bit of snake oil
in the internet portrayal of the magical properties

 

[freefrog]

Yeah sounds that way

The gauss is close
the Inductance is close
the sound of a pickup with either one isn't dramatically different

makes it seem as though there is a bit of snake oil
in the internet portrayal of the magical properties

Good news: if really you feel like that, you won't waste your time no more in tedious comparisons. ;-)

For the rest: I've done my best to reply to your original question in the most precise and factual way.

That's why I've reffered to rules of physics and tech specs which are the polar opposite of "snake oil". :-D

Incidentally, my replies above were all wrote with a genuine intention to help.

So, I'll leave these posts there.

Have a nice day and enjoy with (or without) your magnets and other realities of your life, whatever they are...


EDIT - I agree with the idea that changing a magnet has often a subtle tonal effect, BTW. But if memory serves me, Seymour was describing A2 as "the musical magnet" and it wasn't necessarily without reason.

 

[freefrog]

According to what I've already tried to share: if two bar magnets of a same size and mass give respectively 4.4H and 4.6H in a same humbucker, the one causing the higher inductance contains more iron and is therefore of a lower grade than the other (except for A3, somehow misnamed since it theoretically gives the highest inductance and weakest magnetism).

if ever it's not true, it's because of differences in mass due to varying size and weight of magnets. In this case, using a precision scale + doing a bit of maths allow to know the inductance to mass ratio and to guess what is the alloy involved.

It's a reliable approach, that I've applied many times. But as a matter of fact, it requires reliable (lab) meters adapted to the task. For what you want(ed) to do, a magnetometer with a Hall effect probe would be required.

Anecdotical example...

A friend noticed once that a same Gibson HB was giving him 4.26H with a short A5 bar and 4.45H with a long A2 one... but also 4.6H with a long UOA5. WTF?

The scale answered: the short A5 and long A2 weighted 16 grams each. The UOA5 was thicker and clocked at 18g.

Inductance to mass ratio:

0.266 H per gram for the short A5.

0.278 H per gram for the long A2.

0.255 H per gram for the UOA5.

Logical within the metallurgical variations between bars coming from different foundries.


Reminder on the typical ferrous content of each AlNi(Co) alloy:

A3 = 60%. There's more iron (and more nickel + a wee bit more of aluminium) instead of the missing cobalt. Hence the higher inductance and weaker magnetism with this old recipe.

A2 = 55% of iron.

A4 = 52%.

A5 = 51%.

A6= 49%.

And so on...

Goes to 34% or even 29% of iron for the highest grades of AlNi(Co). Flux strenght increases while iron content decreases for magnets charged in the same way.


Ceramic gives its lowest inductance to a pickup since it doesn't contain iron. But the inductance test is not required here: without iron, ceramic is not conductive so a simple DCR measurement from both end of a bar will confirm its composition (obvious to most eyes, anyway).


Depending on their amplitude, differences measured on magnets AND in other pickups parts may or may not affect noticed tonal properties - which are not "magical properties"... ;-)

 

[ehdwuld]

Good news: if really you feel like that, you won't waste your time no more in tedious comparisons. ;-)

For the rest: I've done my best to reply to your original question in the most precise and factual way.

That's why I've reffered to rules of physics and tech specs which are the polar opposite of "snake oil". :-D

Incidentally, my replies above were all wrote with a genuine intention to help.

So, I'll leave these posts there.

Have a nice day and enjoy with (or without) your magnets and other realities of your life, whatever they are...


EDIT - I agree with the idea that changing a magnet has often a subtle tonal effect, BTW. But if memory serves me, Seymour was describing A2 as "the musical magnet" and it wasn't necessarily without reason.

Someone is a bit testy

Your own data shows the subtle differences in the the construction and performance

The random variation in scientific measurement and non repeatability being passed of as construction flaws

Science is all about repeatability

 

[freefrog]

Flux strenght increases while iron content decreases for magnets charged in the same way.

... and while iron content decreases, so does inductance of pickups, of course. I lacked of time to illustrate this yesterday so let's share a few last examples to illustrate this last part of my previous post.

Guinea pigs in this test were 2 boutique P.A.F. clones tested with 5 pairs of AlNi(Co) bars.

Each line below mentions the alloy, inductance of the bridge pickup then of the neck pickup, average flux strenght of both bar magnets (moderately charged in this case).

Long A3 : 4.42H / 3.73H. Average flux strength: 225G

Long A2 : 4.37H / 3.69H. Average flux strength: 302G

Long A4 : 4.27H / 3.65H. Average flux strength: 353G

Long UOA5 : 4.22H / 3.56H. Average flux strength:390G

Short A5: 4.14H / 3.51H. Average flux strength: 373G


The flux strenght with the short A5's might have been the value of a lower grade magnet, fully charged. In this case, the inductance measurement (in relation with the mass of these short bars) was useful to confirm the alloy involved.
​

 

[freefrog]

And to conclude my attempts to help for free albeit apparently without success (except for my own pleasure to share and my self-injonction to answer positively in any situation), below is an illustration of how one can measure flux strenght on a magnet. This one was a rather degaussed A5, if memory serves me. Both pics are about the same bar tested on the two sides: litterally ALL magnets show such variations when submitted to the Hall probe of a lab-meter. Hence the interest to average measurements (with at least 3 measurements per side normally). 34.1 mT + 33.3mT / 2 = 33.7mT = 337 G.

We have other magnetometers. This one is handy because portative and easy to operate. But it's a bit on the expensive side, reason why I've not evoked it in my very first answer above.