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Does growl (or bite) come from the pickups?

Discussion in 'Pickups & Electronics [BG]' started by skycruiser, Apr 22, 2021.

  1. skycruiser


    Jan 15, 2019
    TLDR underlined question toward the end!

    I did some searching on this and there was a mixture of related discussion, so I thought I would put this out there directly.

    To help convey what I mean - this is what I am assuming about the output of a bass guitar.

    1. The output voltage signal of the bass is a combination of the filtered pickup output voltage and noise. For this discussion let's assume the noise is negligible and independent of player input to the instrument. Filtering is done by the pots/caps installed in the bass.
    2. The pickup is a type of transducer that converts the (relative) mechanical motion of the metal strings near the pickup to an electrical output signal. Nothing else affects the pickup output (again, neglecting electromagnetic noise/interference). The string construction materials and properties affect the magnitude of the induced fields or currents in the pickup, so I suppose the pick-up response depends both on the motion of the string and the string material. By "nothing else affects the pickup output", I am referring to all of those things we say affect the instrument tone (neck material, frets, bridge, body construction etc.) The impact of all of those features is that they affect the string motion, and therefore only affect the sound by the way they affect the string motion.
    3. The string movement is affected to varying degrees by a wide range of factors that include instrument components, player technique, string construction etc. But the final resulting input to the pickup is solely the string motion, influenced by all of those factors, and the coupling strength of the string to the pickup.

    My view of "growl" (or bite) is that it is a form of distortion. You have the "clean" output signal with no growl, and to some extent can add this distortion that we can interpret as a growl.

    I see two sources of what we might think of as growl.

    One is that the "growl" distortion is a disturbance in the string motion, and the pickup is faithfully passing this waveform to the output with high accuracy. This could be finger related disturbances, string contact with the frets, or any number of physical reasons the string is caused to move in a distorted way. Many discussions on the site discuss ways to produce this type of growl (e.g. technique, string type, setup, action).

    The second type of distortion is one that is due to non-linear (or non-typical) response of the pickup. This could be thought of as similar to a clipping op-amp output, or some other distorted response due to the limits of the electrical component. Basically in this scenario, the pickup is not faithfully producing an output waveform consistent with the motion of the string. The output is distorted (in a good way) because the range or linearity of the pickup is not keeping up with the input from the string.

    So my question is about this second possible source of growl or distortion. Do pickups have non-linear responses to the string motion that results in distortion that we interpret as growl? What is the physical basis for this, if it does exist? (magnetic saturation maybe??) And could this non-linear response be related to or dependent on the rest of the circuit in the instrument (volume pots, tone pot, cap(s)), wires)?

    If there is a pickup produced growl or distortion, it seems to me it is likely an overdriven effect that can be increased by strings with higher magnetic properties. I know properties vary with type of metal and construction, and some are considered "higher-output" strings (all else being equal).

    My reason for asking this is to try to figure out if I'm going in the wrong direction for my search for more growly/bitey pickups for my MIM Jazz. Maybe it would be a complete waste to put $150 into a set of pickups when string change, technique or setup would get me there. Or maybe I'll never get there until I get a set of pickups with a lower distortion threshold, so pick-up change is critical.

    [I know this is long-winded an almost every statement could be argued extensively. The idea was to simplify down the concept so that my final questions about pickups is better understood.]
    EatS1stBassist and Domespeed like this.
  2. markanini


    Jun 25, 2008
    I associate growl with full-range responce with some 2kHz emphasis. I carve out some mids in around 700Hz to enhance the growl further. I'ts rather easy to achieve on a J, that's why think there's a common association. Having pickups fairly high helps as that increases the amount of overtones relative to the fundamental.

    One source of distortion has to do with comb filtering, a consequence of sensing the string at a fixed location: Response Effects of Guitar Pickup Position and Width
    C Stone and skycruiser like this.
  3. Goatrope


    Nov 18, 2011
    Sarasota Florida
    My opinion/answer on the specific question:


    What I hear is strictly a function of setup and right hand attack. That’s how I get the “growl” that I think of when I read these discussions. I can get any bass, with any pickups to produce a “growl”.
    chadds, ezstep, erratick and 6 others like this.
  4. dwizum

    dwizum Supporting Member

    Dec 21, 2018
    You're using a lot of words which often get taken to have slightly different meanings among musicians, so this might be a bit of a challenge to unpack.

    Do pickups have "non-linear" response? Absolutely.

    Pickups don't make a perfect reproduction of the string motion as an electrical signal. Pickups, like all electronic devices, are not perfect in the electrical sense. Pickups inaccurately reproduce the string's signal because of these imperfections. This can be estimated in a theoretical sense by distilling the imperfections down into measurable characteristics (i.e. capacitance, impedance, etc). Because of these imperfections, the pickup will have a response curve in the sense that it reproduces some frequencies in the string differently than others - the very definition of non-linear. This is a part of why pickups sound different from each other - not all Jazz pickups sound the same. Some of these properties are sometimes deliberately manipulated to change the tone of the pickups, i.e. you might change wire gauge in order to shift the response curve of the pickup, because wire gauge impacts the resistance/impedance of the coil. Or you might change the pattern the wire makes when going on the bobbin, since a loosely wound coil will typically have a different capacitance than a tightly wound one.

    Another major factor, of course, is the position and "size" of the pickup's field relative to the string. We can't really think of a bass string as having a singular vibration, since the vibration is not constant along it's length. Position a pickup differently, and the signal is different. Or, use a pickup that senses a wider portion of the string, and the signal is different. The signal is essentially an average of the signal across the pickup's magnetic field, weighted by the strength of the field. This is why a short, fat pickup (like a P bass) sounds differently than a thin, tall pickup (like a Jazz).

    You've mentioned magnetic saturation, and I'm not sure what you mean by that. The strength and size of the magnetic field certainly plays a role in pickup tone. We just discussed the size/position. A stronger magnetic field will produce a stronger signal, but that doesn't really change tone or "growl." The composition of the magnet, and any other metal in the pickup's construction, will play a role as well. Magnets made from conductive materials (i.e. alnico) and/or pickups that have metal in their construction (i.e. a steel blade or steel slugs with a bottom mounted magnet, versus a pickup where the magnet itself is in the center of the coil and there's no other metal) will tend to damp certain frequencies more than a magnet that's not conductive and/or a pickup with no extra metal in it. This is a big part of why switching from alnico to ceramic makes a big difference on the tone - ceramic magnets are essentially more faithful in reproducing the full spectrum, so they can sound harsh, since our ears have been trained to like the more-damped tone from an alnico magnet. Pickup builders that use ceramic magnets often use them in conjunction with steel slugs or blades, which tends to help damp the brittle ceramic tone and reinforce the portions of the signal we're used to hearing more strongly.

    Does that non-linear response contribute to what we consider growl? Yes, I think so.

    Ultimately, if you're trying to decide if pickup choice can add or remove "growl" then I think the answer is yes, but probably for different reasons than you're thinking. Most people associate "growl" with a good upper midrange response. Pickups with a strong midrange are often discussed as being growly. Of course, that's only one component of the picture. String choice and technique are probably the most important components. Speaking as someone who builds and sells pickups, I would tell you to focus on technique first before going down the pickup rabbit hole trying to get more growl. Playing with a growly technique can get a growly tone out of nearly any pickup. Once you know you're doing what you can with technique and signal processing, then you can try pickups. Finding the right pickup will help enhance the growl you're putting into the strings with your fingers/pick/whatever.
  5. skycruiser


    Jan 15, 2019
    Thanks @dwizum! I accept and agree that pick-ups are non-linear when they function normally and that is part of the character. The non-linearity I'm asking about is more of an over-driven non-linearity. When the input is too large or has a spectrum that cannot be handled with the pickup's normal transfer function, does it produce a different type of distortion (basically a different transfer function due to input signal magnitude) and is this related to growl?

    I understand there is some debate on how pickups translate string motion to an output waveform. Historically the concept was that the metal string intersection with and movement in the magnetic field of the pickup induces the current in the coil, but more recently there was a publication that suggests it is the magnetized string doing the work, and the purpose of the magnet is only to magnetize the string. If this is the case, then the magnetic properties of the string will affect the signal level of the output, and if there is a saturation point in the coil that causes this distortion, the more highly magnetized string might get you there with smaller vibrations. (Of course moving the pickup closer to the strings will also affect the magnetic field strength of the string). But the point is, with a given pickup, a string change to one with higher magnetic properties may get you to this higher input level and pickup distortion (if it exists) at lower cost than a pickup change.

    Thanks for the advice on how to proceed. I don't have a lot of disposable funds for pickups so I will probably need to focus on technique and maybe investigate strings. I'm getting what I think of as zero bite/growl from my MIM, and would like to make some changes to get there.
  6. dwizum

    dwizum Supporting Member

    Dec 21, 2018
    I'm not sure if anyone here is going to be able to give you a precise answer to that specific question about "over drive" or distortion impacting what you hear as growl.

    It is definitely possible to get a distorted signal out of a pickup. Just raise it up as close to the string as physically possible. But that tone is not normally referred to as growl, and I don't think it is what you're after. Of course, you can overdrive any other part of the signal chain as well, and get slightly different overdriven tones - an overdriven pickup sounds different than an overdriven preamp. At any of these points, you can surf the fine line where only a very high output signal causes overdrive (i.e. a note played with really heavy attack), but again, that's not usually what we call growl, in my experience at least.

    Focus on picking/plucking technique, how much attack you play with, playing on the right part of the string, choosing the right strings, adjusting pickup height, EQ'ing to emphasize the right part of the signal. If you're totally stuck after all that, or just want to keep experimenting, try different pickups, or switch to a bass that's known for having a pickup location and format that emphasizes growl. Some basses are going to inherently be more growly based on the size and location of the pickup(s), and some basses are going to be much more flexible, which gives you a lot more freedom by changing pickups. For instance, in terms of tone, basses with two large soapbar pickup routes that are far away from each other are easier to dial in to a specific tone versus a bass with one pickup, or a bass with an inflexibly shaped pickup. Swapping pickups in a two-soapbar bass can more easily give you a range of tones than swapping pickups in a '51 P bass or a Jazz bass, for instance.
  7. I don't believe it's the pickups, it's the physical action of the vibration of the string to the fret.

    So yes technique will get you farther than replacing pickups.

    If it were electronic then someone could create a growl pedal, like a mwah pedal, they would sell great if they
    actually could make that happen. Mwah to me is the same thing actually minus the frets of course.

    Perhaps a good test of this would be to rest your ear on the body of your bass. Try your ear to the neck too.
    You'll easily hear the overdriven natural vibration sound from your bass, try different dynamics to see how it changes.

    Interesting subject to ponder.
    Carl Hillman and skycruiser like this.
  8. C Stone

    C Stone

    Sep 4, 2020
    Technique, set-up, EQ=GROWL!
    fauxtoe, pbass888 and Goatrope like this.
  9. dwizum

    dwizum Supporting Member

    Dec 21, 2018
    Just noticed in your signature that your bass is fretless. Setup has a lot to do with tone on a fretless, much more so than on a fretted bass. Action and relief contribute pretty significantly to how much the string vibrates against the fretboard as you play, vs vibrating freely. The string vibrating against the fretboard gives fretless basses their distinct muted attack and different sustain characteristics than fretted basses, and those characteristics are essentially adjustable in a way that's not possible on a fretted bass. A lower action tends to give more of a mwah tone with a softer attack, and a higher action gives a cleaner tone that's closer to a fretted bass and makes it easier to have a harder attack. If you're familiar with making adjustments on your bass, you may want to try higher/lower action and see if that helps you get the growly bite you're after.
    Bushmaster and skycruiser like this.
  10. Domespeed


    Oct 7, 2010
    I indeed have heard of non-linear things happening in a magnetic pickups apart from the obvious non-linear frequency response.

    Unfortunately, I have forgotten the terms that go with these things, but as I understood it, it goes in the direction auf saturation of the coils and the magnetic field.

    All the articles I found while googling with the search words "magnetic pickup", "saturation" etc. tend to be very scientific and go beyond my horizon, like these:


    skycruiser likes this.
  11. skycruiser


    Jan 15, 2019
    Thanks, I have tried a range of adjustments and 4 different sets of strings on the fretless and one conclusion I have come to is that I won't get to the tone I'm looking for with this bass as it is. I'm in the process of working out a neck swap to a fretted neck (planning to sell the loaded, fretless this afternoon in fact). I like some of different left hand techniques you can use on a fretless but I don't think it's what I need to play at this stage. I hope to get a better range of tones and playability with the fretted neck. In fact I have been vacillating between pickup and neck swap in my mind, but since I found a local buyer for my neck, I'm planning to make that change first.
    dwizum likes this.
  12. markanini


    Jun 25, 2008
    Magnetic saturation doesn't necessarily have to correlate with audio saturation, or may happen outside of voltages generated from normal playing. An active pickup would have have a more distinct linearity issue due to the extra circutry that has a definite max voltage before saturating.
    To know for sure you would have to set up a test using a driving coil feeding a signal at various voltages: Measuring the Electrical Properties of Guitar Pickups | GuitarNutz 2
    There might be some modulation as the string oscillates across the magnetic field of the pickup that contributes to growl, but I'm just speculating. I'm not sure how you would test that, strings can only move a certain way.
    Last edited: Apr 22, 2021
  13. skycruiser


    Jan 15, 2019
    Thanks, these look to be over my head but worth a review! From a quick read through of the first one, it appear to me that they use the first model of pickup function I mentioned above, where the signal is produced from the action of the metal string cutting through the fields produced by the pickup magnet. It does not seem to consider the motion of the magnetized string near the pickup coils.

    This is the article that describes the alternate view of pickup operation (this article has been discussed on TB in the past):

    How Does a Guitar Pickup Really Work? | Guitar World

    As you suggest, pickups likely have a well behaved but frequency-dependent linear response. This could be specified as a gain level that is a function of frequency (probably phase is also involved). When the input signal remains low enough, the gain vs. frequency function will faithfully pass the input to output according to that gain function. But my speculation is that there are physical limits to this, such at at some input level, the gain function breaks down (frequency dependent) causing a distortion of the output signal. It may be related to well understood saturation effects in power supply transformers. But this is just speculation. My gut tells me that there must be a limit to the ability of a pickup to maintain a constant frequency dependent gain function. Surely they can't operate over an infinite range of input signal levels. But I have no idea what amount of overhead is built into the design. Maybe you would need a guitar string magnetized to 1000x the typical level in a normal bass guitar setup, so you will never reach this distortion level. If this is true then maybe all of the growl effects are in technique. But if this is not true, it may be that we are always operating near this distortion level and some of what we think is technique is actually pickup distortion.
    Domespeed likes this.
  14. EatS1stBassist


    Apr 15, 2016
    So cal
    Nah! Change those pickups! Fender73? Maybe! Then make sure the strings-cable-amp deliver the goods!!
  15. micguy


    May 17, 2011
    When I think of growl....I associate it with the goodness that comes with things pushed in the 1.6kHz region. Some folks think of growl as pushed low mids. What I'll discuss is what affect the frequencies that I call growl.

    To start with, everything you hear from a bass (aside from hiss and hum) originates with how the string is moving. It's construction (round vs flat, and many other details) determine in part how it moves. How you strike it, including whether or not you've bounced parts of the string off a fret is obviously a huge part of how the string ends up moving - that part of your tone is absolutely in your fingers (and the frets that the string bounces off of). There is definitely acoustical stuff (physical vibrations) involved in getting growl. The end conditions of the string (what it's attached to at BOTH ends) also affect the string's vibration. Hint for those wanting more sustain - the end of the string with the huge block of metal attached to the huge block of wood is not what is limiting your sustain - that "other end" with the tiny bit of metal attached to the smaller bit of wood is where you're losing vibrational energy.

    Now, moving on to the pickups. Magnetic pickups are somewhat non-linear devices. If a string is a tenth of an inch from the thing, and you strike it so it's moving half of that distance at its maximum excursion, when it's closer to the pickup, it's now half the distance - the distance has changed by a factor of two from its rest position. Going the other way, it's maximum excursion is reached when it's 1.5 times as far away as the rest position. Given how magnetic pickups work, this results in a signal that is not the same as the movement of the string - it's "gently" distorted - the non-linearity gives you a lot of even order harmonics (hey, that's just like a tube). Those are part of growl.

    Now, the electrical response. Your pickups and your cable (assuming a passive bass) form a filter - the capacitance of the cable you use is DEFINITELY part of your bass's sound. Yes, there is interwinding capacitance in the pickup itself, but the cable usually has more - it's all part of one filter. As the resonance of a typical pickup and cable combination is in the upper midrange (where what I call growl exists), experimenting with cables of different capacitance (or using cables with the same construction, but with different lengths) can help you dial in your ideal growl.

    Oh, and....this is very important. Pickup placement is a huge factor in the mid frequency content of your bass. A P bass (for example) pushes the low mids - you CAN'T give ONE frequency for what it pushes most; it's a wavelength filter - that means the frequency that the location pushes is different on every string. A P bass thus has lots of low mids - that's where the max output of one pickup in that location shows up. A J bass, with both pickups on, has a pronounced dip in that same region (a little higher, actually), which takes away that low mid heaviness, and substitutes a "scooped" sound. By taking away low mids, the upper mids of a J are more audible (a J also has more extension of the upper mids before the thing resonates and then rolls off - two J pickups in parallel are a lower inductance than a typical single P pickup).

    So, what gives you growl? Turns out it's a bunch of things. Some of it is in your fingers. Some of it is in a magnetic non-linearity. Some of it is in the strings, some of it in the pickup/cable combination.
    Last edited: Apr 22, 2021
    skycruiser likes this.
  16. dwizum

    dwizum Supporting Member

    Dec 21, 2018
    That is definitely a thing - all you have to do in order to make it happen is raise the pickups. Or in the course of experimentation, build a pickup with magnets that are much too strong (ask me how I know!). As in any sort of distortion caused by over driving a component, you reach a point where additional amplitude starts getting traded for more harmonics. It's pretty different than distortion at other stages, and you'l know it when you hear it.

    Technique, plus a configuration (pickup, EQ, etc) that naturally emphasizes the frequencies that we perceive as contributing the most to growl. Which is why there is at least some legitimacy to the question of "which pickups are the most growly" or "which bass is the most growly."

    But, again, I don't think that "growl" in the sense we all talk about it is caused by over-driving the pickups. You can build a pickup with very weak magnets and/or lower the pickup well past the point that pickup distortion is no longer possible (no matter how hard you play) and still get a growly tone.
    ahbradot and Domespeed like this.
  17. Jazzdogg

    Jazzdogg Less barking, more wagging!

    Jul 29, 2006
    San Diego, CA
    FWIW, several year ago I bought a fretless Lakland 55-94, which came strung with rounds. It growled to such an extent that, for my taste, it was unplayable. Switching to TI jazz flats and increasing the distance between the fingerboard and the strings eliminated the growl, which made me exceedingly happy. The only adjustment I made to the pickups was to make them conform to the fingerboard radius; the adjustments were slight.

    Good luck in your quest to achieve your ideal sound. :)
    Johnny Fingers and skycruiser like this.
  18. skycruiser


    Jan 15, 2019
    Cool, so it sounds like you have experience where you could identify that the pickup design made it susceptible to overdrive leading to a distorted output signal directly from the pickup. This is exactly what I was wondering about - if it is possible and something we experience. Now my question, how much of the "growl" can this account for?

    As an example, I hear a range of growl/bite sounds in this demo video comparing 4 different Aguilar Jazz bass pickups. Is this variation due to the player's technique or do these pickups have different sensitivity to input causing variation in their level of output distortion?

    Or is the pickup-produced distortion a "bad" distortion such that no pickup manufacturer would design that into the pickup? Is pickup distortion a type of distortion to be avoided?
  19. Corevalay

    Corevalay Supporting Member

    Sep 10, 2009
    New Jersey
    To answer your question as simply as possible.... Yes. I truly believe the pickup model helps produce growl.

    Better, more punchy pickups will result in growl. However, I also believe pickup placement (70s vs 60s), fingerboard wood, and the bass itself will also factor into this. Oh, there's also your amp and cabinet! Lot's of factors for sure, but I fully believe the pickups would make a difference.
  20. JeezyMcNuggles


    Feb 23, 2018
    Santa Maria, CA
    I suck, but nobody really notices
    Growl and bite are two totally different things. The bite comes from your attack. How you pluck and fret.

    Growl is a mid range thing where instead of a boom, thud, or mellow purr, your bass growls. Like aaaaaaarrrrrrrrrrrrrrrrrr.

    Those are both clean tones. Distortion roars. Clean growls.
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