Magnet Strength And Pickup Tone

[Ben]

I know that using more windings increases output but changes the tonal qualities, and that using different types of magnets affects the tone too, but what about using 2 magnets of the same type? would this just increace the output of the pickup, or would it have some sort of an effect on it's tone too?

[crafty]

It depends on where the magnets are placed and what kind of magnets they are. More powerful magnets won't necessarily increase the output of the pickup alone--but they will increase the magnetic field around the pickup and improve sensitivity. More windings mean more power, but sensitivity is reduced because of the resistance, so more powerful magnets are used to compensate. Ceramics are used because they don't increase inductance and reduce sensitivity, too.

I have a Gibson 500T pickup that uses three ceramic magnets. It has a regular center magnet and two smaller magnets that replace the spacers on either side. Very hot pickup, but very clear and not muddy at high volumes.

[Mike Sulzer]

If you find a way to use two magnets and increase the field strength, you might alter the sound by "string pull". The magnets pulling on a string alter the vibration; in an extreme case you can pull the horizontal and vertical modes apart by more than 1 Hz.

I know that using more windings increases output but changes the tonal qualities, and that using different types of magnets affects the tone too, but what about using 2 magnets of the same type? would this just increace the output of the pickup, or would it have some sort of an effect on it's tone too?

[SwedishLuthier]

More powerful magnets won't necessarily increase the output of the pickup alone--but they will increase the magnetic field around the pickup and improve sensitivity. More windings mean more power, but sensitivity is reduced because of the resistance, so more powerful magnets are used to compensate. Ceramics are used because they don't increase inductance and reduce sensitivity, too.

Correction:

The voltage that is generated by a pickup follows this formula:

ems=N *dΦ*1/dt

ems = the induced voltage

N = how many turns of coil wire

dΦ = change in field strange of the magnetic field

1/dt = the frequency of the change in the magnetic field

I might be using wrong letters or names for the physical quantities. This comes from my old collage book for electromagnetic physics, and it’s not in English

Ems is the output of the pickup. dΦ is caused by the string vibrating in the magnetic field and thus causing a fluctuation in it. So this gives us that the factors that affect the output of a pickup is the number of turns and the strength of the magnetic field. So if all other variables are constant and you increase the magnetic field with stronger magnets you will actually get a hotter pickup (higher voltage generated). Ceramics are used purely because they are cheep. Everybody says that ALNICO (ALuminum NIckel Cobalt) is THE musical magnet and ceramics sound hard, and edgy. That is not true. ALNICO5 is a medium strong magnet and help to generate the traditional output in a humbucker. Replace them with ceramics and you will get stronger output and more highs (frequency depending voltage generating). But the same thing is true if you use the stronger ALNICO8 magnet. It is actually stronger than ceramics and generates a tone very similar to ceramics. But ALNICO8 is much more expensive so the manufacturers use ceramics instead. The stronger magnets in high output pickups are used for two reasons:

1 Rise the output and

2 compensate for the loss of high frequencies in over wound pickups

A common misunderstanding is that more windings change the spectral response of a pickup. Not so. The loss of high frequencies on hotter pickups are caused by using thinner wire to get more turns of wire on standard pickup bobbins. High frequencies travel along the outside of the wire and with thinner wire there are less outer area to travel along compared to the total cross section of the wire.

[Mike Sulzer]

"A common misunderstanding is that more windings change the spectral response of a pickup. Not so."

It certainly does. Increasing the number of windings increases the inductance of the pickup (and slightly increases its capacitance). This lowers the resonant frequency of the pickup (the resonance is caused by this incuctance in conjuntion with the cable capacitance and the capacitance of the elecrostatic coupling between the windings). Lowering the resonant fequency reduces the number of highs if the original resonace was within the frequency range of the guitar, and it usually is.

[Ben]

Ok, thanks everyone.

"A common misunderstanding is that more windings change the spectral response of a pickup. Not so."

It certainly does. Increasing the number of windings increases the inductance of the pickup (and slightly increases its capacitance). This lowers the resonant frequency of the pickup (the resonance is caused by this incuctance in conjuntion with the cable capacitance and the capacitance of the elecrostatic coupling between the windings). Lowering the resonant fequency reduces the number of highs if the original resonace was within the frequency range of the guitar, and it usually is.

I hope it does!

Otherwise the multiple heat pickups I intend to make [dea stolen from Robin Griffin on the MIMF, although I think its actually quite an old idea], will be a little pointless!

Thanks