what type of magnets? Bar magnets? I have a chart at work I can send you if so.
i just put my 3.0 gauss meter together ....thanks Elepro......
im using the A1203 sensor. i have been taking some readings of magnets & pickups i just fully charged some alnico 5 magnets ,my meter was reading 650 gauss is there a chart or something of what readings i should get ?
what type of magnets? Bar magnets? I have a chart at work I can send you if so.
thanks ..humbucker bar magnets a5,a2,a3,a4,a8, & rod magnets pretty much everything .
Here's a few standard readings taken right at the end of the magnet
A2 - 578
A3 - 500
A4 - 700
A5 - 680
A5 ISO - 687
A6 - 724
A8 - 1456
A9 - 1620
Ceramic 8 - 1400
PAF Magnet original charge - 460
PAF Magnet Full Charge - 660
These are all .5 x 2.5 x .125 bar magnets. If anyone has any other magnets please let me know as i'll buy them and measure them and add to the list.
I really depends on the magnets themselves.
Getting a 650G off an A5 bar magnet is right in the ballpark, I've had A5 bar mags range from 380G - 770G.
perfect!!!!!! thanks for the information guys
Old thread I know, but I've just lashed up a cheap & cheerful gaussmeter (ie a regulated 5V into an Allegro A1302, then its output into a DVM ....I then manually input the DVM reading into spreadsheet to get a gauss reading - hey, it's not slick but total cost was $2.00 & the results ought to be close enough for Govt work!).
I've no loose magnets to cross correlate the readings mentioned earlier in this thread against against. so just wondered if someone on here could kindly take a reading directly above a pickup at 'string height' for either a single strat type coil or bog standardish humbucker (ok, I know there's no such thing!) ie about 3-4mm above the pickup pole piece....or about 1/8" for those of you still on base 32/64 measuring systems!
I'm measuring about 192 Gauss at the top E 'string height' directly above a Johnny no name humbucker slug piece.
(failing that ....just measuring the top of a slug directly will help me!)
Oh, just one other thing, I'm assuming the 'sensor' interface is the lower part of the A1302 UA type case (as that's where I'm getting the strongest readings) - ie not the head/tip, or the side with the ID/Markings on)
Last edited by peskywinnets; 11-28-2010 at 11:25 PM.
If you want it more accurate than my memory, I can check them again tonight.
Maybe I have been doing this wrong, but I have been using the flat side, not the end or the rounded part.
Your 100 gauss reading is way different to my readings .....I guess we should eliminate the 3/32"s bit and just ask if anyone could take a reading directly against the slug/polepiece top of ahumbucker or strat pickup?!
I'm sure I've the maths conversion right (ie 1.3mV per gauss) ....and my DVM is accurate - it's be nie to get some correlation going on with others' readings.
The flat side is correct for Allegro magnetic field sensors.
Why? If you are measuring an assembled pickup, the magnetic field that counts is where the string would be, and that is what you should measure to compare the field strengths of different pickups. If you are comparing different humbucker magnets, sure, measure against an edge that is a pole. But it is far better to measure the difference in a standard pickup to see what the magnets really do.
To have something repeatable, I put together a Stew mac humbucker kit. The measurements are, 3/32" from the slug or screw, in Gauss:
-118.63412 -120.98911 -129.23170 -136.29675 -130.99792 -117.16220
105.68147 103.03206 104.50398 106.27026 103.03206 113.04093
3/32" from the edge of the magnet alone is about 250 Gauss.
This is an A1322LUA, Device 10, factory calibrated. I use a coefficient of 3.39 mV/G. This is derived by interpolating the three supplied values for three different power supply voltages to get a value for my measured voltage.
I magnetized and measured some 5/8" long stew mac strat type magnets, same setup, 3/32" away. Average value is about 410 gauss.
Baseline DVM reading 2.478V
DVM Reading above slug 2.321V (at string height)
GAUSS (1.3mv per gauss) 120.77 (north)
(I don't normally have a red lead going into the DVM common socket, but I needed a third hand, so pressed the only test lead I had with a croc clip on the end into service!)
that'll do me - cheapest gaussmeter ever - $2.00 for the Allegro sensor, a 78l05 regulator & a strip of scrap veroboard!
Here's some readings on pickups that are sitting on my desk:
From a plastic bobbin alnico 5 strat pickup; Low to high:
745, 740, 637, 730, 647, 693, all North up.
A Duncan Jazz neck pickup reads about 280 (South) on the slug side, and 250 (North) on the screws.
A DiMarzio Al De Meola bridge pickup (alnico) reads 160G. A DiMarzio SDHB reads 420 on the South set of poles and 360 on the North set.
Last edited by David Schwab; 11-30-2010 at 04:06 AM.
Where the string is: There is nothing wrong with assuming a typical distance and using that as a reference. It is a hell of a lot better than measuring where the string never is.
Not in a guitar: Is this a Zen question? Does it relate to the sound a falling tree makes when no one is there? Well, it certainly has nothing to do with the sound of one hand clapping. I prefer to be more practical; it does not make any real difference whether the pickup is in a guitar or not. Measure at the same distance.
I tend to agree, that - for a pickup maker - it's got to be more informative taking a gauss reading where the string is.
It's akin to a sound engineer....he doesn't put his ear up against the PA to get the levels right, he sits where the listener sits - that where the sound level needs to be measured & has to be right. He might hold an interest in how much power the PA can kick out, but at the end of the day, it's the sound level as presented at the listeners' ears that counts.
How come we always get into the "there is only one way to bake a cake" mode?
My take on this is: If you are aiming to produce pickups in a repeatable way consistency is your friend. Measuring with the sensor butting up against the magnet makes a very repeatable way of doing things. Of cause you can make a simple plastic distance gauge and measure magnets in situ in the pickup, but most of us magnetize the bar, test its Gauss level and then assemble the pickup. So it is highly impractical to realize the magnets hasn't been fully charged (or not degaussed to the correct level or whatever...) when you have completed the pickup. Thats why I always measure the Gauss with the sensor directly at the magnet top. But thats just me...
And the out of the guitar Question and answer, is if you are making and selling pickups, not guitars, you want to check the magnet when you charge it.
I'm going to do that with the magnet in my hand, not in air at different distances.
Also if you are checking above the strings, you have so many variables.
If its a strong ceramic, it will be far different than a mildly charged A3, or A2.
Then if you want to use a spacer it would be helpful for that to be standardized. That way if someone here for instance is posting notes about a pickup, it has meaning to you. It's not an arbitrary variable. It would be like a listing of sound pressure levels, where it's rated as x at x inches. But if you measure right at the pole, you know where to take the measurement. That was my point.
Otherwise it makes no difference how you do it.
We also take measurements of magnets before they are in the pickup even though what you read at the pole is different. All good info to have.
If all pole piece types have the same relative decrease of field with distance, then the issue is not of much importance. A constant factor can be used to get form the surface to where the string is.
But I do not think that this is true. Why would the field of a blade fall off at the same rate as a humbucker slug? The geometry is very different.
We want to know what the gauss is at the pole as David said earlier because we want to charge other magnets with a same/similar value and getting closest to the pole just off axis and doing readings works the best.
Your spacer isn't necessary as the sensor is encapulated and it's face has it's own spacer built-in, so again as pickup makers we don't care what the gauss is at 3/32 or 1/8" or whatever because when we build a pickup we don't have any control over the end-user's string height adjustment and we really don't care anyway as it has nothing to do with build consistancy or repeatability in the build process.
I'm not saying it's un-interesting (gauss at string height) just fairly useless to building pickups on a day-to-day basis so doesn't need much churn.
back to the OP's topic...
Id be lost without my gauss meter now ,Especially when M_jo sells me a bunch A2 bar Magnets ,& tries to tell me they are the A8 magnets i ordered , Around 500 gauss A8 fully charged .I don't think so
I should clarify my earlier thoughts - when I said it'd be better to monitor gauss strength at the string...it was with pickup creators in mind .... ie someone creating their own 'signature' & getting deep down 'n dirty with collecting data .....if it's just for churn/repeatablity, then yeah, measure it wherever you care - and the pole or the magnet face is the most obvious & easiest place.
Cliff Claven was certain he was using his brain power.
"Well you see, Norm, it's like this... A herd of buffalo can only move as fast as the slowest buffalo and when the herd is hunted, it is the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members. In much the same way, the human brain can only operate as fast as the slowest brain cells. Now, as we know, excessive drinking of alcohol kills brain cells. But naturally, it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine. And that, Norm, is why you always feel smarter after a few beers."
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