The magnetization of a pickup effects the output of a pickup and one of the big influencers is the material type of Pole Pieces, and of course, the design of the pickup itself.
Alnico is Aluminum, Nickel, and Cobalt (see lower chart for more info)
AlNiCo III |
600-800G |
AlNiCo II |
800-900 G |
AlNiCo V (and IV) |
900-1100 G |
Ceramic |
800-1100 G |
Samarium Cobalt |
More on the upper end of Alnico V and Ceramic |
Magnet Gauss their sound and use (subjective):
Alnico 2 magnet pickups tend to produce soft and articulated low ends, wide and rich midrange, sweet treble, and low output. A mellow magnet that’s great for finger picking, Country, Blues, Folk, Indie and Classic Rock. ~ 530-590 Gauss for a traditional pickup bar magnet.
Alnico 3 magnets, weaker in magnetic strength than alnico 2, have more treble and a softer bottom end, with lower output than alnico 2. The softness is great for deep sparkling cleans, perfect for Soft Rock, Blues and Funk. ~ 470-490 Gauss for a traditional pickup bar magnet.
Alnico 4 magnets give flatter EQ which makes them “transparent” to the guitar’s natural resonance. This magnet is great for true projection of resonance making it perfect for Jazz, Pop, Indie. ~ 630-670 Gauss for a traditional pickup bar magnet.
Alnico 5 magnets generate lots of tight lows, balanced midrange, powerful and sharp highs, higher output and a slightly tighter sound. This is probably the most used magnet in guitar pickups today. The elevated volume and the wider eq make it very popular and versatile. Best for Rock, Metal, Funk, Jazz, Pop. ~ 710-770 Gauss for a traditional pickup bar magnet.
Alnico 8 magnets have the strongest magnetic field of all Alnico. Lots of mids, fat highs and massive lows. It is not frequently used because of its strong magnetic pull and massive output. Great for Metal, Hard Rock, Fusion and Prog. ~1200-1320 Gauss for a traditional pickup bar magnet.
Ceramic magnets are even stronger than Alnico, making them louder with pronounced mids and a quick bass response. Due to harsher high frequencies they are used more commonly by players who use distortion and they tend to sound thin and lifeless when playing clean, according to many guitarists… Usually charcoal black in color which makes them easy to identify. ~ 1250-1300 Gauss for a traditional pickup bar magnet. NOTE: Ceramic is typically on Made in Mexico Fender Stratocasters or Squiers, but can be found on other pickups like Hot Noiseless. The range of output is also a bit larger so there is more deviation from pickup to pickup.
CHARGED OR NOT CHARGED
Nothing is stranger than measuring the DCR (DC Resistance) of a pickup, installing it, and it has no output. One reason for this is the pickup has been demagnetized. A Gauss meter will tell the story, I measured a “dead” pickup once and it’s output was about 40 Gauss, uh err, ok, that is almost completely, but not quite, discharged.
FULL CHARGED OR NOT?
Another interesting thing is that if a pole is fully charged it doesn’t necessary mean it’s best. Some pickups sound quite harsh if the pole piece is fully charged.
PICKUP STRENGTH AND DISTANCE
The damping effect is the reason why you shouldn’t get too close to the strings with a pickup
The B-field from an electric guitar pickup poles decreases rapidly as one moves away from them, the exact dependence is rather complicated due to the finite size of the poles (diameter & height) as well as the presence of magnetically permeable and other permanent magnets in proximity to the magnet pole undergoing measurement,
This is why placing a magnet under a pole pieces also increases their strength.
DAMPING EFFECT ON STRINGS
The closer the pickup is the the string the louder it’s output BUT it also has a damping affect on string sustain as it gets closer.
LACE SENSORS (and some other noiseless pickups)
When you try to measure these you can’t get directly in contact with the pole pieces. At a small distance the Gauss measurement is quite low at the top of the pickup, around 250 Gauss or so. This is the reason why Lace Sensors can be VERY close to the string without damping on the string very much.
Here’s an excerpt from BILL LAWRENCE and a link to his website
Ceramics vs Alnico
When I read that ceramic magnets sound harsh and alnico magnets sound sweet, I ask myself, ” Who the hell preaches such nonsense?” There are harsh-sounding pickups with alnico magnets and sweet-sounding pickups with ceramic magnets and vice-versa! A magnet by itself has no sound, and as a part of a pickup, the magnet is simply the source to provide the magnetic field for the strings. The important factor is the design of a magnetic circuit which establishes what magnet to use.
Though ceramic magnets cost less than alnico magnets of equal size, a well-designed magnetic circuit using ceramic magnets costs much more than the six Alnico 5 magnets of a traditional single coil pickup!
Aging
Before the introduction of alnico magnets in 1935, permanent magnets were not quite that permanent. During a certain time, they lost a good amount of magnetism till they finally reached a stable condition. The process to accelerate this decay was called in the industry, “magnetic aging.” In modern science, it is called “stabilizing.” Since the �50’s, we use Alnico 5 magnets which lose, under normal conditions, less then half a percent per 100 years.
How do we achieve normal conditions?
Alnico magnets are shipped by the manufacturer in a non-magnetized condition and will not be magnetized until a pickup is completed.
How to maintain normal conditions?
After magnetization, avoid any close contact with other pickups or magnets facing either north to north or south to south with their magnetic poles. Don’t ever throw pickups random in a drawer; you may either use a keeper on each side of the magnetic poles or carefully place them with the north facing the south pole of the other magnet. ( For tele players, remember that the iron backplate of a traditional tele pickup functions as a keeper which increases the stability of the magnets.)
Once pickups are in a guitar, there is very little to worry about. That your pickups lose some of their magnetism when you lean your guitar against an amp is nothing but a fairy tale. Or, that pickups lose some of their magnetism when you drop them on a concrete floor is just another fairy tale — alnicos and ferrites will break before they have any measurable losses. Magnets are sensitive to heat, but so is your guitar. However, heat can be a severe problem when an Alnico 5 magnet is exposed to temperatures above 1000 F, approaching its Curie temperature of 1634 F. At these temperatures, Alnico 5 undergoes structural changes and cannot be re-magnetized. Why do I mention this? Because it happens quite often, when someone doesn’t like the unbalance in output of a pickup with staggered magnets and goes to a bench grinder or a belt sander to grind a magnet down. You take a chance that a magnet gets too hot and becomes damaged.”
GAUSS values for pole materials
Magnetic material Gauss Oersteds Max. Energy
Alnico 2 7500 560 1.70
Alnico 3 7000 480 1.35
Alnico 4 5600 720 1.35
Alnico 5 12800 640 5.50
Alnico 5 DG 13300 670 6.50
Alnico 5-7 13500 740 7.55
Alnico 2-sintered 7100 550 1.50
Alnico 5-sintered 10900 620 3.95
Ceramic 1 2300 1860/ 3250 1.05
Ceramic 2 2900 2400/ 3000 1.80
Ceramic 5 3800 2400 3.40
Ceramic 7 3400 3250/ 4000 2.75
Ceramic 8 3850 2950/ 3050 3.50
Samarium Cobalt 18 8700 8000 18.00
Samarium Cobalt 20 9000 8700 20.00
Samarium Cobalt 22 9500 6500 22.00
Samarium Cobalt 24 10300 5500 24.00
Samarium Cobalt 26 10000 6300 25.50
Samarium Cobalt 30 11000 5200 30.00