info on magnet gauss levels

[kevinT]

Did some testing on some mags. I'm posting the results if folks are interested. If anyone has different readings with their tests/experience, please add.

I used the Carlsen Melton gauss meter to measure the strength of the magnet before (as I received them from the vendor) and after charging to a full charge. I used the big magnet charger (the $500 one) that possum, wolfe, and others have.

The sizes of the magnets are the typical 2.5 x .5 x .125 bar magnets for humbuckers

To get a representative sample, I picked 3 mags from various orders that I received or I chose them from the same shipment of mags but various positions within the brick (i.e. end of brick, middle of brick, and some in between).

I took 3 readings and used the highest reading. On some mags, I took a couple more readings when the numbers were unclear.

The mags were purchased from Magnetic Hold and Allstar.

Here are my results

A2
Before Charging (as they came) Full Charge
1. 554 North 486 South 627 North 671 South
2. 533 North 493 South 635 North 671 South
3. 446 North 457 South 626 North 630 South

A3
Before Charging (as they came) Full Charge
1. 407 North 461 South 531 North 534 South
2. 407 North 465 South 554 North 533 South
3. 414 North 438 South 541 North 543 South

A4 Suppliers were out of stock when I placed order, sorry

A5
Before Charging (as they came) Full Charge
1. 491 North 567 South 927 North 930 South
2. 611 North 598 South 786 North 801 South
3. 765 North 747 South 721 North 796 South

A6
Before Charging (as they came) Full Charge
1. 644 North 621 South 768 North 741 South
2. 721 North 605 South 838 North 915 South
3. 633 North 576 South 740 North 756 South

A8
Before Charging (as they came) Full Charge
1. 1171 North 1253 South 1370 North 1494 South
2. 1216 North 1336 South 1469 North 1407 South
3. 1297 North 1288 South 1355 North 1368 South

Ceramic 5
Before Charging (as they came) Full Charge
1. 1251 North 1259 South 1251 North 1291 South
2. 1252 North 1269 South 1255 North 1287 South
3. 1297 North 1210 South 1293 North 1210 South


Ceramic 8
Before Charging (as they came) Full Charge
1. 1211 North 1216 South 1219 North 1274 South
2. 1141 North 1190 South 1197 North 1221 South
3. 1195 North 1204 South 1242 North 1199 South


What surprised me were the wide differences in the gauss of the A5s. This is probably one of the reasons why PAFs sounded differently. Can anyone explain this phenomenon?

Also, on a couple readings the gauss seemed to decrease after a full charge, can anyone explain this?

[Spence]

AlNiCo of all grades will lose some charge after they have been magnetised. That's normal. The A5 gauss levels will be on a par with A4 so you should expect that when you get A4. The differing gauss readings between gardes of alnico are directly because of the ratio of magnetic component to non-magnetic ones in the alloy. For example, a large element of copper in the alloy will severly reduce the gauss potential.

[Possum]

normal...

You said these were all received charged. Magnets aren't charged one by one they are charged in big bundles or bricks so each magnet receives a different varying charging level, so of course they will vary alot. If you get a charger they will be more uniform, though there will be those that don't hold a charge as well.....

[kevinT]

You said these were all received charged. Magnets aren't charged one by one they are charged in big bundles or bricks so each magnet receives a different varying charging level, so of course they will vary alot.

Yep, I purchased in quantities of 100 to 200 (they came in bricks and these were probably taken from much bigger bricks at the factory). Some of the magnets that i tested were from different lots (bricks) that i purchased on different occassions. For example, the A5s that i tested were from three different lots that i had purchased at different times. In another sample, the A3s were from the same lot (brick) but individual magnets were chosen from different areas of the brick to get a variety of samples.

If you get a charger they will be more uniform, though there will be those that don't hold a charge as well.....

For sure....I have and used the charger that you and wolfe have.

[Spence]

Kevin, don't waste any of your time worrying about gauss.
I have published my findings on gauss levels of vintage guitars in a UK magazine a while ago. Now, they were Strats but the one's that everyone liked had been played and played and played. The 1957 collector's item was the only one with fully charged magnets and it sounded harsh to me. It's the same for all guitar pickups. If you want vintage, check the gauss of the magnets going in the set of pickups and put the strongest in the bridge. You may even charge up the magnet for the bridge. If you don't want vintage charge them all up.

[kevinT]

The 1957 collector's item was the only one with fully charged magnets and it sounded harsh to me. It's the same for all guitar pickups. If you want vintage, check the gauss of the magnets going in the set of pickups and put the strongest in the bridge. You may even charge up the magnet for the bridge. If you don't want vintage charge them all up.

I agree. I also think fully charged mags generally make the pickup sound harsh/too bright. If the individual mag doesn't read at the level that i want it to be when i take it out of the brick, i knock it down or I charge it to the max and knock it down from max to where I want the level to be.

I did these readings a while back and I guess i wanted to list my results because there is no where on the forum where it specifies the different grade magnets and thier maximum gauss levels. I know there were some posts in the past that asked about certain mag types and their relative maximum strength. I try to help when i can.

[Spence]

You know what, it's a very good bit of work you've done there.
I don't know how well it will be thought of by others here as you used a Carlsen Melton which some on this forum consider to be a pile of shit. Personally, I think it's the best value and most indestructabl and reliable gaussmeter I have ever had the pleasure of using.

[SkinnyWire]

Those measurements look pretty "normal" to me. It's even more interesting if you take multiple meaurements across the length of the pole faces to see the differences there.

They charge the brick, but the instant you pull them from the brick the charge is typically reduced 15-30%. The sliding and different things that can happen as you pull them apart have an impact on that. I don't know if irreversible damage can happen during that process or not (typically heat related I think), but for whatever reason some magnets simply don't hold the same level of charge as others of the same grade. Odd goings on in the alloy mix? Permanent damage somehow/somewhere along the way? Doesn't mean it can't be used, maybe just in more specific applications.

I find A5 to be the most "finicky" and unstable grade and the most difficult grade to balance across the faces. YMMV. I spend entire evenings just trying to get 10-15 magnets set up for installation sometimes.

Knowledge (actually measuring the field strengths) is power, but it's also a bitch sometimes.

[kevinT]

I don't know how well it will be thought of by others here as you used a Carlsen Melton which some on this forum consider to be a pile of shit.

I would like to know the reasons why they think that. The company has a comparison chart of other manufacturers' products on their website that is impressive IMO. I also purchased the calibration cert. They calibrate the device with other high end measuring equipment.

IMO...the bottom line is that it is easy to use, affordable, and i believe pretty damn accurate for our purpose. And i highly recommend it.

Personally, I think it's the best value and most indestructabl and reliable gaussmeter I have ever had the pleasure of using.

I agree...I love mine too. I think the price went up since i purchased it.

[kevinT]

Those measurements look pretty "normal" to me. It's even more interesting if you take multiple meaurements across the length of the pole faces to see the differences there.

man...that would be a very tedious endevour (if it can even be done) because the numbers are constantly changing as you move the magnet pole face across the sensor....unless you take measurements at different intervals along the magnet (every 1/4 inch)...that might be one way to do it....still a lot of work.

I find A5 to be the most "finicky" and unstable grade and the most difficult grade to balance across the faces. YMMV. I spend entire evenings just trying to get 10-15 magnets set up for installation sometimes.

I agree...i find that they are very finicky too. Some of the A5s drop their charge quite considerably and quickly from the time i remove the mag from the charger.

For example, on one mag i got a reading of 907 gauss right after i removed it. Within a minute it dropped to 867 gauss and i couldn't get the 907 reading again.

For shits and giggles, last night i did some tests on some stewmac A5 magnets that i had lying around for a while.

Here are the results.
Before Charge After Charge
1. 647 N/485 S, 867 N/851 S
2. 599 N/627 S, 836 N/832 S
3. 590 N/553 S, 854 N/874 S

[kevinT]

Also, on a couple readings the gauss seemed to decrease after a full charge, can anyone explain this?

I just realized in my first post the last statement wasn't very clear.

Some of the magnets decreased in gauss below the number that i measured before the full charge.

For example: I got a reading of 786 before full charge and 757 after full charge. So it dropped below the initial number.

[Possum]

bar magnets

If you're measuring bar magnets for buckers they won't have an even charge across the edges and tend to have higher charges on the ends, some don't though. I think it also depends on how you charge them too. The charger itself isn't charging perfectly evenly across the edges. I just measure in the middle of the bar as a reference point. To further complicate things once you put rod magnets in a single coil they will act as a unit linked together and the end poles will show a higher charge :-)

yeah Spence's gaussmeter is a pile of shit....just kidding. They are all really pretty much the same its just the housing thats different. I got the Alphalab one which has the hall sensor on a ribbon wire, sometimes its a pain to use unraveling the long lead its on, but its real sensitive and will measure the earth's gauss, I'm sure they all do. Advantage to my pile of shit is that if the hall sensor fails you just buy another one and plug it into the connector, happened last year, $80 replacement charge, ouch.

[Spence]

The good thing about the Carlsen Shite-o-Meter is that you can hold the button down and find the highest gauss over the whole pole face. That's pretty useful.
interestingly I remember Mick telling me that his humbucker magnets were not showing equal gauss across the whole pole face by quite large amounts. Turned out it was the ham-fisted way he was charging them. But hey, everyone's on a learning curve no matter how brilliant you think you are.

[David Schwab]

Advantage to my pile of shit is that if the hall sensor fails you just buy another one and plug it into the connector, happened last year, $80 replacement charge, ouch.

They were talking about Gauss meters over at MIMF recently, and discussing the same two meters. Someone mentioned that the hall sensors are delicate, and one disadvantage of the Alphalab is the sensor can be damaged from handing.

I have no experience with either meter, so I can't say they are right.

[SkinnyWire]

man...that would be a very tedious endevour (if it can even be done) because the numbers are constantly changing as you move the magnet pole face across the sensor....unless you take measurements at different intervals along the magnet (every 1/4 inch)...that might be one way to do it....still a lot of work.




I agree...i find that they are very finicky too. Some of the A5s drop their charge quite considerably and quickly from the time i remove the mag from the charger.

For example, on one mag i got a reading of 907 gauss right after i removed it. Within a minute it dropped to 867 gauss and i couldn't get the 907 reading again.

For shits and giggles, last night i did some tests on some stewmac A5 magnets that i had lying around for a while.

Here are the results.
Before Charge After Charge
1. 647 N/485 S, 867 N/851 S
2. 599 N/627 S, 836 N/832 S
3. 590 N/553 S, 854 N/874 S

Tedious? Damn right it is. I cast aside quite a few A5 magnets in the quest for "even" charge across the face of the bars. By even, I don't mean the exact same measurement but ...

I made a jig to ensure I measure each magnet the same every time at six points (hey, six strings right?) across each face of a bar. I've developed some tricks to leveling things out as much as possible and no there's not much fun to it at all. Also, I'm not sure it's absolutely necessary since I've pulled magnets out of very nice sounding pickups and the field strengths were 30G apart north to south and up/down the lengths. I'm just a bit anal about it I suppose.

Possum is right in that they do tend to measure higher at the ends, I suppose due to the sharp corners. This is quite noticeable after charging. They don't seem to drift much after I tweak them though.