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Do electric guitar (or bass) pickups sound different only because of EQ?

I understand the strength of magnet and totality of wire windings effects the strength of the signal but if one wanted to make one pickup sound like another would a very good EQ be able to achieve that?

That is, why buy multiple electric guitars if you can get an EQ that can 'tune in' the sound of any pickup.

(For this discussion please ignore 'tone wood'. I have seen many videos attempting to demonstrate the effect of wood on solid body guitar tone and the differences seem minor at best, but significant on an acoustic.)

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    It's a fair question, I don't understand the downvote. In essence you're asking, could a magnetic pickup be simulated with a sufficiently detailed EQ curve. This idea of simulating equivalence is like with speaker cabinets, which - excluding unwanted distortion - can be reproduced with impulse responses that are so short that they can be said to be equivalent to very detailed EQ curves. But pickups - is there more to them. It's not self-evidently clear that there's more, so it's a fair question. Jan 19 at 5:48
  • As a side note, I noticed that if you put EMG pickups on differentguitars, you get an EMG sound, with more or less sustain depending on the guitar. Many characteristics seem to disappear behind the sound of these pickups.
    – Thomas
    Jan 19 at 19:11
  • @piiperiReinstateMonica Why a downvote? Easy answer. If the answer isn't absolutely perfect for the person reading the answer it's a downvote. In 50 questions I've posted, and I'm not a bad writer, I've had perhaps 3 with net-positive ratings. Jan 19 at 20:58
  • @Thomas You're probably thinking of EMG's active pickups (ie: the 81/85, etc), and that's more a trait of active pickups generally - nothing particular about EMG. Other active pickups behave similarly, while EMG also makes passive pickups with a more traditional response.
    – J...
    Jan 20 at 14:52
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    The pickups may be non-linear (roughly speaking - adds harmonics). That won't be simulatable with EQ (and to the extent it is fixable, you'd need different settings for each note). For instance (extreme example), if the physical sound the pickup receives is a sine wave, and pickup A clips it so the electrical signal looks more like a square wave, you are going to have a hard time simulating that with EQ on pickup B which does not clip.
    – abligh
    Jan 21 at 8:01

3 Answers 3

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EQ is a linear change of signal: it does not matter in which order you place the EQ sections for the result of sound, and if you double the signal in front, you get out exactly double the previous result at the end.

A pickup, in contrast, has the magnetic flux through its coils modified as the string travels through its magnetic circuit and completes it in some manner. If it were working in a linear manner, there would be no difference between playing louder and cranking the volume pot up.

That may work to some approximation when you microphone your electric guitar and amplify those results (or rather record them if you are not keen on feedback). There are things like piezo bridge pickups: those will tend to have a better chance of being made to sound similar via EQ since they have a comparatively linear, "microphoning" response. That does not mean that the frequency response is even, but merely that it is in some fixed relation to the input frequencies, and with EQ you can tweak that relation.

But the magnetic pickup action is rather far from being a linear thing so you'd need something seriously more contorted to have a chance to map one kind of pickup to the sound of another.

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    @RandyZeitman Linear system means that in theory there could be a corresponding reversing "undo" system which gives the original signal. For EQ it's theoretically like this. If the EQs are linear, it doesn't matter in which order you place them, the end-result is the same. But if you have a non-linear system such as a distortion pedal - or any processing which causes distortion - then there is no perfect "undo" even in theory. Something is lost within the process. And then the processing order matters. For example, dynamics processors such as compressors are non-linear systems. Jan 19 at 22:12
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    @Randy Zeitman - Linear is the correct term, in the sense of a mathematically linear system (en.wikipedia.org/wiki/Linear_system). The "multiple EQ sections" is referencing if you had multiple EQs run one after another; if you had 2 EQs with different settings and connected input->EQ1->EQ2->output, the output would be the same as if you connected input->EQ2->EQ1->output - the order doesn't matter. Jan 20 at 0:53
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    @piiperiReinstateMonica "Linear system means that in theory there could be a corresponding reversing "undo" system" - That line might confuse people, since it sounds like it's meant to be a loose definition of "linear". I can design a distortion circuit with a corresponding "undistortion" circuit. That doesn't make it linear (but if there was no possible undo, then at least we know it's definitely nonlinear)
    – Edward
    Jan 20 at 0:53
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    Linear transformations are not necessarily commutative nor invertible. What distinguishes a linear transformation from a non-linear one is that putting two signals through a linear transformation individually and then adding the result will have the same effect as adding the two signals together and putting the sum through that same transformation.
    – supercat
    Jan 20 at 20:11
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    Are pickups really linear? What I remember from physics lectures is that ferromagnetic materials have all kinds of weird behaviour and permanent magnets are even weirder.
    – ojs
    Jan 21 at 14:27
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From a physics perspective...

Different pickups have different magnetic fields. The magnetic fields have different shapes and sizes.

Part of what makes typical humbuckers sound different from single-coil pickups is the fact that the magnetic field on a humbucker covers more of the string. When it covers more of the string, that means that the string's higher modes (higher frequencies) will cancel out more. This is part of why typical single-coil pickups sound brighter than P90s, and P90s typically sound brighter than humbuckers.

Another factor that makes pickups sound different is the overall frequency response of the pickup. When you add more windings to a pickup, the output levels get higher, but it also increases the inductance and parasitic capacitance of the pickup, which makes the pickup sound darker. The wire also has resistance to it, and a higher resistance (thinner wire) will dampen the natural resonance of the pickup (reduce the Q factor).

In theory, you can adjust for the frequency response with EQ, but you cannot use EQ to adjust how big the magnetic field is. The problem is that making the magnetic field bigger, like for a humbucker, has a different effect on each string.

The reason why it affects each string differently is because you can think of it kind of like an EQ, except instead of applying an EQ to different frequencies, the EQ applies to different wavelengths. For example, if you have a magnetic field that is 2cm wide, then it will pick up a wavelength of 8cm just fine, but a wavelength of 2cm will be highly attenuated.

Each string has a different relationship between wavelength and frequency. So, changing the shape of the magnetic field is kind of like applying a different EQ curve to each string! Once all the strings are mixed together, you can't do that. That is why it is not possible to make a humbucker sound like a single coil pickup, or vice versa, using EQ.

Now consider that different pickups have lots of different magnetic fields. For example, you can get pickups with pole magnets or bar magnets. Also consider that when a string vibrates, it moves through different parts of the magnetic field... if you hit a string hard, it won't line up with the pole pieces, but with a bar magnet, that doesn't apply. These are differences that you can't just EQ out.

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  • This is the single best explanation for what makes pickups different, that I have ever read. Jan 21 at 17:38
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Short Answer is definitely NO.

Long Answer. EQ were existing long before digital signal processing. As it was mentioned, EQ comprises of Linear Change of the signal. Let's make it more clear. When you view at the signal as Fourier spectrum over some big approx 0.1s window, Ideal EQ only changes relative height of these peaks and does not change the harmonic structure. Technically, EQ is nonlinear operator over spectrum, but they were made to not touch the harmonic structure. Old EQs were just filters of the signal coming over series of RC or RL electric filters. Those were not changing your harmonic structure FOR SURE. So definitely NOT with passive elements.

Then the era of passive EQs came to an end, and then EQ became all active, which means that there is transistors which are having positive-negative feedbacks. First, making good EQualizer even with todays circuit design is a HUGE pain. And all EQ curcuitry had drawbacks as unwanted nonlinear actions over your signal. So deeply theoretically you can compensate for some other elements inside your signal trunk. But doing so with transistor technology is HUGE pain up to the point that even now simple analog amplifiers with transistors cannot successfully emulate even other vacuum tube amplifiers (hence the usage of VT amps is not discontinued despite them having their drawbacks).

And now, the digital EQ, which is not actually "real" EQ. Lets see, you got ADC-DAC converting of the signal. Which can only be successful up to some bit depth. I guess the best what today's ADC can do is 12-bit conversion for mass production. So you got discrete time and discrete levels, you are not doing even actual Fourier spectrum via integrating, you are doing Fast Fourier Transform, which only "resembles" the frequency spectrum of your signal. Digital EQ = "FFT image editing". It is not successful in on-the-fly activity. But people are using it a lot to noise-clean or level-edit their voices in-record. Because in studio you can afford to write sound in environment of 100dB accuracy and with at least 32-bit depth of signal. FFT is moving to it's limit, actual Fourier Transform, at maximum accuracy (infinite bit depth + infinite sampling rate).

Even so, if doing "editing Fourier image" can theoretically lead to editing the tembre or harmonic structure of your signal, which can mimic the tembre of instrument or some other element in your "signal trunk". There is very LITTLE to do about those harmonics which were suppressed by elements before your digital editing starts. You cannot "uncompress" harmonics which were supressed before because of laws of entropy. Ones your information is lost without backup you cannot turn that process back. Same what happens when you upscale a JPEG image without sophisticated tools.

About sophisticated tools AKA neural network editing etc. It exists, but it exists only for very few tasks which it was calibrated for. Long calibration, testing, huge work just to improve some quality of few tasks like improving the quality of sound from very old vynil record.

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    How is this related to guitar pickups?
    – ojs
    Jan 21 at 14:25

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