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Number of Turns vs Resistance

3/18/2006 2:36 PM
Paul D.	Number of Turns vs Resistance Would you guys check me on this? A pickup's DC resistance figure is often given as an indicator of its output. Is Number of Turns not a truer indicator of output and, if so, then could one build a pickup with many turns of heavier wire thus giving high output with low DC resistance? I think Les Paul did this with his "Recording" pickups. I'm asking because I'd like to build a (passive) bass pickup that's powerful and has a wide frequency range. I'm aware that this been a goal for bass pickup makers since the dawn of time so this problem has surely come up before. Cheers, -Paul D.

3/18/2006 2:36 PM

Paul D.

Number of Turns vs Resistance

Would you guys check me on this?
A pickup's DC resistance figure is often given as an indicator of its output. Is Number of Turns not a truer indicator of output and, if so, then could one build a pickup with many turns of heavier wire thus giving high output with low DC resistance? I think Les Paul did this with his "Recording" pickups.
I'm asking because I'd like to build a (passive) bass pickup that's powerful and has a wide frequency range. I'm aware that this been a goal for bass pickup makers since the dawn of time so this problem has surely come up before.
Cheers,
-Paul D.

3/18/2006 5:10 PM
Dwight Listmayer	Paul, here's a thingy I pasted while the scholars of this forum ponder your challenging question. I think it's cool when fewer turns of thicker wire produce less K ohms resistance, while delivering smooth, wide-range sound. That's the stuff dreams are made of. Bass pickups can be quite unique because they are not required to transmit alot of trebles, like an electric guitar should do. So, some different theories could be tried, while remembering the principles of inductance per Joseph Henry. Inductance, quantity that measures the electromagnetic induction of an electric circuit component; it is a property of the component itself rather than of the circuit as a whole. The self-inductance, L, of a circuit component determines the magnitude of the electromagnetic force (emf) induced in it as a result of a given rate of change of the current through the component. Similarly, the mutual inductance, M, of two components, one in each of two separate but closely located circuits, determines the emf that each may induce in the other for a given current change. Inductance is expressed in henrys [for Joseph Henry]. An inductor is a device designed to produce an inductance, e.g., a coil; an ideal inductor, i.e., one having no resistance or capacitance (see impedance), is often called an inductance. Okay, the preceding was the paragraph I copied. I'm trying to learn something from it, I think? 'Cuz I don't have an answer but wanted to add something, while I'm interested in the topic. I have a 1978 MIJ P Bass copy with a 4K pickup that sounds quite nice. Smooth 'n Creamy like Betty Crocker's icing, hehe. Just my nickel's worth. Strat man Dwight

3/18/2006 5:10 PM

Dwight Listmayer

Paul, here's a thingy I pasted while the scholars of this forum ponder your challenging question. I think it's cool when fewer turns of thicker wire produce less K ohms resistance, while delivering smooth, wide-range sound. That's the stuff dreams are made of.

Bass pickups can be quite unique because they are not required to transmit alot of trebles, like an electric guitar should do. So, some different theories could be tried, while remembering the principles of inductance per Joseph Henry.

Inductance, quantity that measures the electromagnetic induction of an electric circuit component; it is a property of the component itself rather than of the circuit as a whole. The self-inductance, L, of a circuit component determines the magnitude of the electromagnetic force (emf) induced in it as a result of a given rate of change of the current through the component. Similarly, the mutual inductance, M, of two components, one in each of two separate but closely located circuits, determines the emf that each may induce in the other for a given current change. Inductance is expressed in henrys [for Joseph Henry]. An inductor is a device designed to produce an inductance, e.g., a coil; an ideal inductor, i.e., one having no resistance or capacitance (see impedance), is often called an inductance.

Okay, the preceding was the paragraph I copied. I'm trying to learn something from it, I think? 'Cuz I don't have an answer but wanted to add something, while I'm interested in the topic.

I have a 1978 MIJ P Bass copy with a 4K pickup that sounds quite nice. Smooth 'n Creamy like Betty Crocker's icing, hehe.

Just my nickel's worth.

Strat man Dwight

3/18/2006 6:02 PM
Fred Hammon	Les Paul did this and Epiphone reissued it as the Jack Casady Signature bass, a version of the Les Paul Signature bass. These pickups are low impedance. Their output signal is boosted with a transformer with a 3 position VariTone (VariOhm) switch. Casady claims to have had a hand in the redesign of this lo-Z pickup and sez they came up with #28 gauge...which is large indeed. (Somehow I think that could be a mistake - or a misprint) you can't get very much #28 wire on most 4 string bass bobbins. Anyway, what I'm trying to get across is that the bigger the gauge the lower the resistance but at some point you exceed the most desirable combination of factors for a hi-Z single coil bass pickup which seems to be pretty much what you'd find in most J type pickups etc. You can fool around with short and fat or tall and thin coil geometries or less wire vs more magnet etc. It's really all been done. Having said all that, if you've got the time I would encourage you to experiment with traditional pickup designs using progressively bigger gauges of wire with alnico and ceramic or even neo magnets and see what happens. Then let me know!

3/18/2006 6:02 PM

Fred Hammon

Les Paul did this and Epiphone reissued it as the Jack Casady Signature bass, a version of the Les Paul Signature bass. These pickups are low impedance. Their output signal is boosted with a transformer with a 3 position VariTone (VariOhm) switch.
Casady claims to have had a hand in the redesign of this lo-Z pickup and sez they came up with #28 gauge...which is large indeed. (Somehow I think that could be a mistake - or a misprint) you can't get very much #28 wire on most 4 string bass bobbins.
Anyway, what I'm trying to get across is that the bigger the gauge the lower the resistance but at some point you exceed the most desirable combination of factors for a hi-Z single coil bass pickup which seems to be pretty much what you'd find in most J type pickups etc. You can fool around with short and fat or tall and thin coil geometries or less wire vs more magnet etc. It's really all been done.
Having said all that, if you've got the time I would encourage you to experiment with traditional pickup designs using progressively bigger gauges of wire with alnico and ceramic or even neo magnets and see what happens.
Then let me know!

3/19/2006 3:55 PM
Mark Hammer	While you can't take a pickup and measure the number of turns from the outside with any degree of accuracy, you can always measure the DC resistance with as much accuracy as your meter can muster. Consequently, while #turns IS what matters, DCR has become the de facto means of measurement "out there" simply because of convenience and simplicity. It's a bit like describing a student based on their GPA rather than the strengths and weaknesses of their actual thought content. Not particularly accurate with respect to what matters, but in the ball park for all practical purposes. That being said, you are absolutely correct in wondering about whether one could turn out a high output pickup that had a very low DCR. I used to have one of the aforementioned low-impedance LP pickups (bought at the old Parsons Street Gibson facility in Kalamazoo for $18 shortly before it closed and resurrected as Heritage Instruments). It was much taller profile than normal, heavy as lead, and had a magnet that would stop a Mack truck form moving. But, it was very powerful at the same time as having a very low impedance. You will note that the style of music Les Paul was playing involved lots of notes held for only a brief period of time each on thick strings. In this context, the heavy pull of the magnets did not present any disadvantage the way it might using very light strings and trying to squeeze longer finger vibrato sustain out of the strings. Such pickups also don't present a disadvantage when using thick bass strings either. On a related topic, you will also note that a dual-coil humbucker can be wired in parallel OR with the coils in series. The one will result in a lower DC resistance than the other, even though the number of turns has not changed. Finally, I remember reading one of Jeff Baxter's old columns in Guitar Player some 30 years ago, where he discussed matching humbucker coils for number of turns so that hum-rejection could be maximized. Following his advice, I matched the two coils in a pickup I had for DCR, using a 4-1/2 digit DMM for extra precision. Bringing their respective DC resistances within less than 1% of each other DID result in better hum-rejection (though there have been many cogent discussions here about the tonal benefits of sacrificing a bit of hum-rejection for the richer sound of two mismatched coils). So, to some extent, if the coil-winding is consistent, the wire gauge identical, and the coil dimensions the same, DC resistance CAN be used as a reasonable substitute for counting turns. Just remember that you can get higher and lower DC resistances in many different ways, and that what always matters in the number of turns.

3/19/2006 3:55 PM

Mark Hammer

While you can't take a pickup and measure the number of turns from the outside with any degree of accuracy, you can always measure the DC resistance with as much accuracy as your meter can muster. Consequently, while #turns IS what matters, DCR has become the de facto means of measurement "out there" simply because of convenience and simplicity. It's a bit like describing a student based on their GPA rather than the strengths and weaknesses of their actual thought content. Not particularly accurate with respect to what matters, but in the ball park for all practical purposes.

That being said, you are absolutely correct in wondering about whether one could turn out a high output pickup that had a very low DCR. I used to have one of the aforementioned low-impedance LP pickups (bought at the old Parsons Street Gibson facility in Kalamazoo for $18 shortly before it closed and resurrected as Heritage Instruments). It was much taller profile than normal, heavy as lead, and had a magnet that would stop a Mack truck form moving. But, it was very powerful at the same time as having a very low impedance.

You will note that the style of music Les Paul was playing involved lots of notes held for only a brief period of time each on thick strings. In this context, the heavy pull of the magnets did not present any disadvantage the way it might using very light strings and trying to squeeze longer finger vibrato sustain out of the strings. Such pickups also don't present a disadvantage when using thick bass strings either.

On a related topic, you will also note that a dual-coil humbucker can be wired in parallel OR with the coils in series. The one will result in a lower DC resistance than the other, even though the number of turns has not changed.

Finally, I remember reading one of Jeff Baxter's old columns in Guitar Player some 30 years ago, where he discussed matching humbucker coils for number of turns so that hum-rejection could be maximized. Following his advice, I matched the two coils in a pickup I had for DCR, using a 4-1/2 digit DMM for extra precision. Bringing their respective DC resistances within less than 1% of each other DID result in better hum-rejection (though there have been many cogent discussions here about the tonal benefits of sacrificing a bit of hum-rejection for the richer sound of two mismatched coils). So, to some extent, if the coil-winding is consistent, the wire gauge identical, and the coil dimensions the same, DC resistance CAN be used as a reasonable substitute for counting turns. Just remember that you can get higher and lower DC resistances in many different ways, and that what always matters in the number of turns.

3/20/2006 8:39 AM
David Schwab	One thing I want to add about dual-coil humbuckers wired in parallel... this is one of the things I dislike about EMG P pickups, since they are wired in parallel they have a big hole in the mids. While the parallel wiring does lower the DC resistance and therefore gives a sound with more highs and lows, it lacks midrange. I much prefer to wire the coils in series and just wind less wire on them.

3/20/2006 8:39 AM

David Schwab

One thing I want to add about dual-coil humbuckers wired in parallel... this is one of the things I dislike about EMG P pickups, since they are wired in parallel they have a big hole in the mids.

While the parallel wiring does lower the DC resistance and therefore gives a sound with more highs and lows, it lacks midrange.

I much prefer to wire the coils in series and just wind less wire on them.

3/21/2006 2:07 AM
Paul D.	"since they are wired in parallel they have a big hole in the mids" Yes David, I agree entirely! This is the basis of the Jazz Bass sound - I happen to like the sound (like the "Smiley-face" EQ sound) but I always add a series/parallel switch to all my twin pickup instruments (mostly basses). To my ears, series = power & punch, parallel = mellow & "hollow". Cheers, -Paul D.

3/21/2006 7:23 AM
David Schwab	Paul, I don't mind two pickups in parallel as much as I don't care for the two coils of one pickup in parallel... at least not on bass! The EMG P is a nice sounding pickup, but I can't help but think it would sound so much fuller in series. I do like that Jazz bass sound, but even then, two pickups in parallel always seems to lack something. Take a Gibson Les Paul for example. I hate the sound with both pickups on! It's less than the sound of either pickup by its self. I know this is because of both the impedance interaction, and also the over lapping frequencies on the pickups. I think there has to be a better way. On one of my basses where I wound the pickups and made my own preamp, I have an actual mixer section to blend the two pickups. That takes care of the impedance interaction. The two pickups never "touch" each other. One of these days I'm going to experiment with filtering out the over lapping frequencies and see what that does (when both pickups are combined). Should be an interesting sound option! Having two different sounding pickups helps a lot too.

3/21/2006 7:23 AM

David Schwab

Paul,

I don't mind two pickups in parallel as much as I don't care for the two coils of one pickup in parallel... at least not on bass! The EMG P is a nice sounding pickup, but I can't help but think it would sound so much fuller in series.

I do like that Jazz bass sound, but even then, two pickups in parallel always seems to lack something. Take a Gibson Les Paul for example. I hate the sound with both pickups on! It's less than the sound of either pickup by its self. I know this is because of both the impedance interaction, and also the over lapping frequencies on the pickups. I think there has to be a better way.

On one of my basses where I wound the pickups and made my own preamp, I have an actual mixer section to blend the two pickups. That takes care of the impedance interaction. The two pickups never "touch" each other. One of these days I'm going to experiment with filtering out the over lapping frequencies and see what that does (when both pickups are combined). Should be an interesting sound option! Having two different sounding pickups helps a lot too.

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