Magnet Strenght vs Tone

[tbryanh]

I know people are convinced the strenght of the magnet affects tone, but I am thinking that it only affects how hot the pickup is.

1. Volume controls affect tone.
2. The volume and tone controls on a guitar do not operate independently. Adjusting one changes the effect of the other.
3. Turning down the volume control on a hotter pickup in an attempt to get the same amount of distortion causes the tone to change, but this is due to the volume control and not the pickup.
4. Different grades of Alnico affect tone differently, but this is because different grades of Alnico affect the inductance of the coil differently. It has nothing to do with the different strengths of the magnetic fields of the various grades of fully charged Alinico slugs.

Please comment.

[David Schwab]

Magnet strength has a correlation on how bright the pickup is. This is why you find hot wound pickup with ceramic magnets. Put an alnico in the same pickup and it will be a lot darker sounding. I've done this on some of my bass humbuckers. The exact same size alnico bar magnet was quite darker sounding. Some would call it "mellow" or "vintage".

A lot of winders degauss their magnets for this reason. It's for the tone they get. It's the same magnet... same inductance, but less flux.

Ceramic magnets don't really add too much to the inductance like metal alloy magnets do, and difference strength ceramics do sound different. Add more ceramic magnets and the pickup gets brighter.

Turns affects output more than anything, but only up to a point of diminishing returns.

You might get a little more juice out of a pickup by putting in a stronger magnet, but you will also change the tone.

The poles make a difference too... more inductance means more output.. once again up to a point, then it just gets muddy.

The other thing about magnets is the surface area of the pole is what counts. So a thicker magnet in a humbucker will be more powerful, even if it's the same alloy and grade.

The controls form a load. The more load, the more top end gets rolled off.

Best thing is to try everything you can! It's time consuming, but fun.

[OFM]

I've been doing some research with magnet strenght recently...

First of all... I don't like "High Gain" pickups at all...

(stop reading if you don't want to know about high-gain experiments, hehehehe)

But I have a lot of friends and customers who loves that pickups, one of them is in fact a great luthier and knows a lot about tone, wood and hard rock music (he tests guitars with heavy distortion, and I don't know how does he distinguish every tone in a guitar with such amount of gain... but he does... and does well)

He asked me for the highest gain pickup i could make without killing tone, so I started my research.

I made some overwound bobbins, with a single ceramic magnet, but he didn't find the pickups powerful enough. I added 2 ceramic magnets (made a 3 ceramic pickup) and he was blown away. The pickup was hot enough, but retained tone. I found the pickup too bright for my taste, but he liked it a lot.

I've tried also with a less wound (6500 turns of 43AWG per bobbin) with a big-fat ceramic magnet and the results were great too. The pickup sounded better, with similar magnet strength, but it was more responsive. Since it had less wire and a single (big fat) magnet, it wasn't as powerful as the first one.

This time, bobbins were more important for tone and response, but magnet strenght raised the amount of gain.

Now we're trying to make a heavy wound bobbin with neo-mags... yes... i'm trying to make a NEOBUCKER... HEHEHEHE...

Of course I didn't use an entire Neodymium bar, this would dampen the strings and demagnetize any pickup or credit card, attract rings, earrings or anything around it. I used small neodymium magnets, distributed around the pickup. I haven't wound the pickup yet, but i measured the magnet stranght and it was just a bit stronger than the 3-ceramic-pickups (that was my original intention).

I'm not spending much time on that research right now, since i don't really like highgain pickups, i'm even disliking humbuckers since last months, but maybe this week i'll wind the first prototype.

(and of course i'll tell you how it works... even if it sucks... hehehehehe)

Greetings!
Ben

[corduroyew]

I know people are convinced the strenght of the magnet affects tone, but I am thinking that it only affects how hot the pickup is.

There is an easy test you can do to find out for sure. Build a pickup (I would suggest a single coil) and install it into your guitar. When you install it, bypass your switches and pots. Just hook it straight to the output jack. This makes it so you can’t blame the darker tone on your pots. Start the pickup off with fully charged alnico magnets. Play the guitar and note what you hear. Then take a neo magnets and wave the like pole over the pickup 1 or 2 times to degauss the magnets. Then play the guitar some more. You will notice the guitar is a bit quieter but you will also notice that the guitar is warmer with less cutting high end.

[Joe Gwinn]

There is an easy test you can do to find out for sure. Build a pickup (I would suggest a single coil) and install it into your guitar. When you install it, bypass your switches and pots. Just hook it straight to the output jack. This makes it so you can’t blame the darker tone on your pots. Start the pickup off with fully charged alnico magnets. Play the guitar and note what you hear. Then take a neo magnets and wave the like pole over the pickup 1 or 2 times to degauss the magnets. Then play the guitar some more. You will notice the guitar is a bit quieter but you will also notice that the guitar is warmer with less cutting high end.

Demagnetizing also cuts output by the same amount (likewise the background noise), and so the ear hears less of the highs and lows, so for a fair experiment, you must turn the gain up to compensate. In other words, the tests must always be at the same volume (measured at the ears).

[tbryanh]

Demagnetizing also cuts output by the same amount (likewise the background noise), and so the ear hears less of the highs and lows, so for a fair experiment, you must turn the gain up to compensate. In other words, the tests must always be at the same volume (measured at the ears).

Good point. The ear responds nonlinearly to highs and lows in relation to sound pressure level (SPL).

I think between the volume control affecting tone and the nonlinear response of the ear, it is possible there is a big misconception that magnetic strength affects tone.

My understanding is that the properties that affect tone are inductance, capacitance, resistance, and distortion.

It does not appear that the strenght of the magnetic field affects inductance, capacitance, or resistance.

Assuming that the volume control is used to adjust the output of the pickup to the same level, then distortion is not an issue either.

I suspect strongly that it is the act of adjusting the volume control that affects tone.

I am open minded. If the strenght of the magnetic field affects tone, then I would like to know how it does it.

[corduroyew]

Demagnetizing also cuts output by the same amount (likewise the background noise), and so the ear hears less of the highs and lows, so for a fair experiment, you must turn the gain up to compensate. In other words, the tests must always be at the same volume (measured at the ears).

Agreed. You do need to turn the gain up on the amp to compensate for the lower output of the pickup. I guess I should have mentioned that too.

[David Schwab]

I think between the volume control affecting tone and the nonlinear response of the ear, it is possible there is a big misconception that magnetic strength affects tone.

OK, but I make fully buffered pickups that never "see" the load from the controls. I've experimented with swapping magnets on the same pickup, and I can easily hear a difference.

Also I'm working with low impedance coils, so I hear more of the magnetic circuit than with a pickup with a lot of windings.

My understanding is that the properties that affect tone are inductance, capacitance, resistance, and distortion.

Inductance is really about magnetic inductance. They are magnetic pickups, after all! If you have a weak magnet, it cannot saturate the coil with enough flux, and you will get a duller tone. The more inductance in the magnetic circuit, the more output with less winds. Inductance plays a bigger part than capacitance.

But it's all of the above, not just the strength of the magnets.

[soundmasterg]

The thing about pickups is that all the things that make it up are inter-dependant. Changing the turns count changes the inductance, capacitance, resistance, and the tone. Likewise, changing the magnet type or strength does the same. You can't really talk about changing one of the factors in isolation and not think that it won't change one of the other factors too. Thats part of what makes it so hard to analyze what is going on in the sound of a pickup. Moreover, not everything regarding the sound of something can be shown on test equipment. There are things we don't understand about how we hear and they aren't easily measured.

[Zhangliqun]

Dave is right, but another aspect that may be overlooked is a stronger magnet probably also has a wider magnetic field (assuming a magnet of the same dimensions), meaning it will "see" a larger portion of the string and pick both more lows and highs.

Different strength magnets will have different shape/size magnetic fields that will see different points of the string differently -- each point on the string has a different tonal character, bassier/stronger/fatter the closer you get to the middle of the string (12th fret) and vice versa as you get closer to the bridge. Thus variations in magnetic field size, shape, and intensity will emphasize the various parts of the frequency spectrum differently.

A wider magnetic field will also see the longer wavelengths on the string better in general, regardless of its position relative to the string, meaning more bass than a narrower magnetic field centered at the same point.

So yes, magnets do very much affect tone.

[tbryanh]

To Test
1. Keep the field strong enough to cover all the windings. Then we know all the windings are participating, and we also know that the width of the field around each slug is wider than the "width" of the string when the string is vibrating.
2. Keep the field weak enough to avoid saturating the core and clipping the signal.
3. Keep the core centered on the string to avoid asymmetrical distortion.
4. Connect the pickup to an onboard preamp to eliminate the effects of volume and tone controls, guitar cord inductance/capacitance, etc.
5. Place a sound pressure level (SPL) meter in front of the amplifier speaker.
6. Place a microphone in front of the speaker.
7. Send the signal from microphone to a spectrum analyzer.
8. Adjust the amplifier for a SPL that produces a clean signal with lots of headroom.
9. Install various sets of slugs into the pickup. Each set of slugs are of the same alloy but have different magnetic strength charges.
10. For each set of slugs that gets installed, test all strings and all frets.
A. Pluck each string on the guitar separately and in the same manner. Move your finger to a new fret each time.
B. Adjust the amplifier to produce the same SPL each time a string is plucked.
C. Take a photograph of the spectrum analyzer display each time a string is plucked.
D. Label each photograph.
11. Analyze the photographs.

[tbryanh]

An item that has been left out of the discussion is the Q of the LCR circuit in the coil.
The inductance and capacitance in the coil form a bandpass filter.
The passband is centered around a certain frequency, the resonant frequency of the LCR circuit.
The resistance of the coil affects the Q of the circuit, the more resistance, the lower the Q.
The Q of the circuit determines how wide the passband is, the lower the Q, the wider the passband.
The width of passband affects the tone of the pickup.

If the strenght of the magnetic field affects the Q of the circuit, then the strength of the magnetic field would affect the tone of the pickup for this reason.

[soundmasterg]

You also need to make sure in your test that the plucking of the string is done in a consistant manner. Best to not use a finger at all and use some kind of mechanical plucker so the plucking strength can be ruled out as a variable.

[Joe Gwinn]

An item that has been left out of the discussion is the Q of the LCR circuit in the coil.
The inductance and capacitance in the coil form a bandpass filter.
The passband is centered around a certain frequency, the resonant frequency of the LCR circuit.
The resistance of the coil affects the Q of the circuit, the more resistance, the lower the Q.
The Q of the circuit determines how wide the passband is, the lower the Q, the wider the passband.
The width of passband affects the tone of the pickup.

If the strength of the magnetic field affects the Q of the circuit, then the strength of the magnetic field would affect the tone of the pickup for this reason.

The magnetic field strength will only have a second-order (that is, minimal) effect on the resonance and Q of a pickup. What effect there is results from the permeability of the ferromagnetic parts varying with the average level of magnetic flux. Given that most of the magnetic circuit of a pickup is made of air, this effect is largely swamped out by all that air.

[tbryanh]

The magnetic field strength will only have a second-order (that is, minimal) effect on the resonance and Q of a pickup. What effect there is results from the permeability of the ferromagnetic parts varying with the average level of magnetic flux. Given that most of the magnetic circuit of a pickup is made of air, this effect is largely swamped out by all that air.

So its safe to say that the strength of the magnetic field affects tone a very small amount?

And its also safe to say that the strength of the magnetic field affects dynamics (touch sensitivity) a very large amount?