Can someone please explain inductance to me in simple terms?

[Dave Locher]

I thought I had a decent grip on resistance vs. output vs. inductance, but then I got a curveball.
I have been trying to compare some pickups I have used and liked over the years to get an idea of what else I might like to try. These are some stats I found on the interweb:
Gibson "Tarback" around 7.5k ohms, 4.7 henries.
Super Distortion roughly 14k ohms, 6.57 henries
Super 3 25k ohms, 7.53 henries
Lawrence L-500XL roughly 13.3k ohms, 9.2 henries

I thought henries gave a good indication of a pickup's overall output level and treble content (more henries = higher output, less treble) but the Super Distortion and Bill & Becky L-500XL are throwing me for a loop. At 9.2 henries vs. 6.57 henries the L500 seems like it should be much more powerful and have less treble, but neither seems to be the case. The L500XL seems roughly similar in terms of output and seems brighter and less mids-focused than the Super D. I also tried the 8-henry Lawrence L90 and it seemed much brighter AND lower output than the 6.57 henry Super Distortion.
Are these numbers only useful for comparing pickups that are otherwise identical? (Super D and Super 3 seem to fall into that?) OR are the numbers measured differently by different sources??

If someone could explain all of this to me in simple and straightforward terms I would really appreciate it.

 

[beaubrummels]

Re: Can someone please explain inductance to me in simple terms?

Magnet types and how coils are wound can also affect treble. You can't look at 1-2 characteristics and predict what a pickup will sound like. Have to factor everything.

I'll leave the inductance explanation to the EE scientists here.

 

[dotsdad]

Re: Can someone please explain inductance to me in simple terms?



Simple enough, right? :33:

 

[Dave Locher]

Re: Can someone please explain inductance to me in simple terms?

View attachment 88334

Simple enough, right? :33:

Oh yeah, I TOTALLY get it now.

 

[Blille]

Re: Can someone please explain inductance to me in simple terms?

View attachment 88334

Simple enough, right? :33:

Sent from my iPhone using Tapatalk Pro

 

[Securb]

Re: Can someone please explain inductance to me in simple terms?

 

[Hyperborea]

Re: Can someone please explain inductance to me in simple terms?

A current in a conductor generates a magnetic field. That magnetic field opposes changes in the current running through the circuit by creating a counter voltage. The inductance is the ratio of that back voltage divided by the rate of change of the current. It's, as given above, determined by physical properties of the circuit or coil.

 

[freefrog]

Re: Can someone please explain inductance to me in simple terms?

I thought henries gave a good indication of a pickup's overall output level and treble content (more henries = higher output, less treble) but the Super Distortion and Bill & Becky L-500XL are throwing me for a loop. At 9.2 henries vs. 6.57 henries the L500 seems like it should be much more powerful and have less treble, but neither seems to be the case. The L500XL seems roughly similar in terms of output and seems brighter and less mids-focused than the Super D.

I see at least two parameters at work here:
1-the DiMarzio includes a double thick magnet and big fat screw poles, giving a much stronger magnetic field than the thinner mags and blades in a BL;
2-ithe BL has a slightly higher Q factor, translated by a slightly narrower and peaky resonant frequency. It contributes to more perceived brightness.

It doesn't make false what you said: absolutely speaking (all other things being equal) higher inductance = more output and less treble.

It's just that the two pickups in your example have really different designs.

FWIW.

I'll try to post a comparative test chart later if time permits.

 

[dotsdad]

Re: Can someone please explain inductance to me in simple terms?

Sent from my iPhone using Tapatalk Pro

essentially the fancy math problem tells us: the shape of the coil affects the tone. The length of wire changes the tone. The thickness of wire changes the tone. The magnet changes the tone. The non ferrous parts changes tone. Discuss...

Sent from my SM-G930T using Tapatalk

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

View attachment 88334

Simple enough, right? :33:

Notice that the thickness of the wire is not mentioned anywhere. The implication being that if you wind three identical pickups, each with a different gauge of wire, the wire thickness itself won't make a difference, aside from the impact it might have on the overall dimensions of the coil.

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

I thought I had a decent grip on resistance vs. output vs. inductance, but then I got a curveball.
I have been trying to compare some pickups I have used and liked over the years to get an idea of what else I might like to try. These are some stats I found on the interweb:
Gibson "Tarback" around 7.5k ohms, 4.7 henries.
Super Distortion roughly 14k ohms, 6.57 henries
Super 3 25k ohms, 7.53 henries
Lawrence L-500XL roughly 13.3k ohms, 9.2 henries

I thought henries gave a good indication of a pickup's overall output level and treble content (more henries = higher output, less treble) but the Super Distortion and Bill & Becky L-500XL are throwing me for a loop. At 9.2 henries vs. 6.57 henries the L500 seems like it should be much more powerful and have less treble, but neither seems to be the case. The L500XL seems roughly similar in terms of output and seems brighter and less mids-focused than the Super D. I also tried the 8-henry Lawrence L90 and it seemed much brighter AND lower output than the 6.57 henry Super Distortion.
Are these numbers only useful for comparing pickups that are otherwise identical? (Super D and Super 3 seem to fall into that?) OR are the numbers measured differently by different sources??

If someone could explain all of this to me in simple and straightforward terms I would really appreciate it.

Inductance and capacitance combine set the point at which the pickup's treble response drops off. When either goes up, the cut off or "resonant" frequency goes down. The reason inductance is king is because it's much, much higher than the capacitance, in terms of the impact it has. 2 henries or more is considered very high, in general, and part of what makes a pickup cost as much as it does is just the sheer amount of fine wire involved that results in such a high inductance. Most all pickups have a capacitance somewhere between 50pF on the low end, to 300pF on the high side, which is not a lot, and this is true if high and low output pickups alike. Meanwhile, the inductance can range from 2 henries up to 12 henries, for a very high output humbucker.

Inductance is useful to gauge how much treble content you get from a pickup. The lower the inductance, the more treble you get. A typical Strat pickup has an inductance around 2.5H, while a Telecaster bridge is closer to 3.5H. A typical PAF type neck pickup is around 4.5H, while a bridge is wound a little "hotter" to 5.5H. P-90's typically have closer to 8H, and so they're somewhat darker than typical PAF remakes. Hot humbucker such as the JB and Super Distortion are also in the area of 8H.

The actual voltage output actually has little to do with the inductace itself, but related indirectly, sort of like DC resistance. What actually determines the output voltage is the average proximity of the average turn of wire to the guitar string. Think of every turn of wire as an individual pickup. 10,000 turns of wire = 10,000 pickups in series, combining the voltage of each turn of wire. In the same respect that putting the pickup closer to the strings makes the pickup louder, so too is that the case for every turn of wire. The turns of wire that are closer to the string produce more voltage than those which are farther away. Therefore, the overall voltage output is determined by how many turns of wire the pickup's design manages to place closer to the strings. The reason a JB is loud is not because it's inductance or resistance are high, it's for the simple fact that it places many turns of wire close to the guitar string. The higher inductance and DC resistance are merely (some might even say unwanted) side effects.

 

[Dave Locher]

Re: Can someone please explain inductance to me in simple terms?

Okay, so now we are getting somewhere!
So if all other factors are equal, higher inductance means more output and less treble but every other possible construction factor also has an effect? That, I can understand and live with.

One more naive question: if proximity of the wire to the strings is critical, wouldn't wide, shallow bobbins potentially make for an interesting barn burner of a pickup?

 

[Dave Locher]

Re: Can someone please explain inductance to me in simple terms?

Notice that the thickness of the wire is not mentioned anywhere. The implication being that if you wind three identical pickups, each with a different gauge of wire, the wire thickness itself won't make a difference, aside from the impact it might have on the overall dimensions of the coil.

Isn't r the radius of the wire, and hence the size of the 10,000 pickups in series?
I am NOT trying to be a smartass, I really want to understand all of this. I built my own guitar from scratch, but pickups are still this mysterious black box to me. It was trying 5 or 6 different pickups in that guitar that made me realize how much impact they have on the overall sound and feel of a guitar.

 

[beaubrummels]

Re: Can someone please explain inductance to me in simple terms?

Inductance and capacitance combine set the point at which the pickup's treble response drops off. When either goes up, the cut off or "resonant" frequency goes down. The reason inductance is king is because it's much, much higher than the capacitance, in terms of the impact it has. 2 henries or more is considered very high, in general, and part of what makes a pickup cost as much as it does is just the sheer amount of fine wire involved that results in such a high inductance. Most all pickups have a capacitance somewhere between 50pF on the low end, to 300pF on the high side, which is not a lot, and this is true if high and low output pickups alike. Meanwhile, the inductance can range from 2 henries up to 12 henries, for a very high output humbucker.

Inductance is useful to gauge how much treble content you get from a pickup. The lower the inductance, the more treble you get. A typical Strat pickup has an inductance around 2.5H, while a Telecaster bridge is closer to 3.5H. A typical PAF type neck pickup is around 4.5H, while a bridge is wound a little "hotter" to 5.5H. P-90's typically have closer to 8H, and so they're somewhat darker than typical PAF remakes. Hot humbucker such as the JB and Super Distortion are also in the area of 8H.

The actual voltage output actually has little to do with the inductace itself, but related indirectly, sort of like DC resistance. What actually determines the output voltage is the average proximity of the average turn of wire to the guitar string. Think of every turn of wire as an individual pickup. 10,000 turns of wire = 10,000 pickups in series, combining the voltage of each turn of wire. In the same respect that putting the pickup closer to the strings makes the pickup louder, so too is that the case for every turn of wire. The turns of wire that are closer to the string produce more voltage than those which are farther away. Therefore, the overall voltage output is determined by how many turns of wire the pickup's design manages to place closer to the strings. The reason a JB is loud is not because it's inductance or resistance are high, it's for the simple fact that it places many turns of wire close to the guitar string. The higher inductance and DC resistance are merely (some might even say unwanted) side effects.

If I put a JB and a Seth both 3/16" from the strings, how does the JB have more turns of wire closer to the string? If the JB bobbin is taller but still 3/16" away from the strings, then it has more turns of wire away from the string.

 

[beaubrummels]

Re: Can someone please explain inductance to me in simple terms?

Notice that the thickness of the wire is not mentioned anywhere. The implication being that if you wind three identical pickups, each with a different gauge of wire, the wire thickness itself won't make a difference, aside from the impact it might have on the overall dimensions of the coil.

Then why do pickup makers specify min-nom, nom-max, etc. wire for particular model pickups?

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

Okay, so now we are getting somewhere!
So if all other factors are equal, higher inductance means more output and less treble but every other possible construction factor also has an effect? That, I can understand and live with.

Inductance has about as much to do with output as DC resistance. It's the turns of wire that get you the output, it just so happens that inductance and resistance also increase along with the turns of wire, so these three things all track somewhat closely.

Not ever other possible construction factor has an effect, only those that have some sort of reactive or resistive quality, which is to say parts that are conductive or magnetic.

One more naive question: if proximity of the wire to the strings is critical, wouldn't wide, shallow bobbins potentially make for an interesting barn burner of a pickup?

They also need to be close to where the magnetic field is strongest, which means close to the pole piece. If the loop of wire is very wide, then the flux change through the loop of wire will include both the primary and the return path of the magnetic field (positive in one direction, negative in the other) of the moving guitar string, therefore cancelling out the total flux change. That's why a Jazzmaster pickup is not much louder than a Strat pickup.

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

Isn't r the radius of the wire, and hence the size of the 10,000 pickups in series?
I am NOT trying to be a smartass, I really want to understand all of this. I built my own guitar from scratch, but pickups are still this mysterious black box to me. It was trying 5 or 6 different pickups in that guitar that made me realize how much impact they have on the overall sound and feel of a guitar.

r is the radius of the coil. Since a guitar pickup's coil isn't round, that equation isn't quite detailed enough. A rectangle loop model would give a more accurate inductance calculation. Another difference is that those models usually assume an air core, or a solid permeable core, but a pickup has a core that is part air and part permeable material, since there are gaps in between the pole pieces.

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

If I put a JB and a Seth both 3/16" from the strings, how does the JB have more turns of wire closer to the string? If the JB bobbin is taller but still 3/16" away from the strings, then it has more turns of wire away from the string.

The JB uses finer wire, making for a higher density of loops of wire, or a greater overall turn count, for a given set of coil dimensions.

 

[PicoRiveraTele]

Re: Can someone please explain inductance to me in simple terms?

Then why do pickup makers specify min-nom, nom-max, etc. wire for particular model pickups?

I've never seen this information provided by a pickup maker myself. Wire diameter is applicable to the amperage rating, minimizing resistance or mitigating skin effect, or making sure the overall coil size remains small. Since a guitar pickup deals with low voltage in the audio frequency range, only the issue of overall coil size is of concern.

 

[freefrog]

Re: Can someone please explain inductance to me in simple terms?

Okay, so now we are getting somewhere!
So if all other factors are equal, higher inductance means more output and less treble but every other possible construction factor also has an effect?

Somehow. I've here a prototype pickup measuring only 4k for a surprisingly strong 6.1H due to "other construction factors". Although it has four time less resistance than a 16.2k / 6.85H SH13, it has almost the same inductance and sounds accordingly (powerful and beefy like a P90 in this case).

One more naive question: if proximity of the wire to the strings is critical, wouldn't wide, shallow bobbins potentially make for an interesting barn burner of a pickup?

To answer this question, you could try some surface mount transducers, like many Rowe/DeArmond built decades ago for cheap guitars- or their variations. Example:

http://www.ebay.com/gds/Gold-Foil-Guitar-Pickups-Japan-Types-Observations-/10000000178130123/g.html

I've such a pickup (a 1966 Silver Foil) here. 11.52k, 3.86H. It sounds rich and powerful (but squeals like a pig under high gain).

Oh, and... when it comes to wide shallow coils, there's also and of course the (regular sized) Burns tri-sonic and its variations.

FWIW, my personal experience with such shallow coils makes me consider them as prone to unwanted feedback, unless they are properly or heavily potted. The DiMarzio "Brian May" single coils are another example of that (albeit their shallow coils are not wide).

Good luck in your "guitar made from scratch" project. I've also built myself a part of my gear and IME/IMHO, it's worth the effort.