Inductive balancing of cores and windings

[bbsailor]

That's interesting that the eddy currents have the particular effect on the peak's shape. It sounds like you're talking about "bandwidth" being effected, though



I tend to think of the "voice" as being the grand sum of all the factors involved. I think it's fair to say that narrow band widths result in a more shrill pickup, and could be said to determine it's shrillness, or lack there of. If the resonant peak is lower, a narrow bandwidth causes a nice midrange gives way to a nasally honk, which I readily witness when using tone caps between .022 and .003 uF. You can hear all these same things if you mess around with a parametric EQ while listening to music.

To all members commenting on this thread.

When it comes to the evolution of things to be analyzed we tend to get down to the fundamental elements such as in humans it is the DNA but in guitar pickups it is the LCR. However, in LCR pickup analysis we are looking for how the response graph shapes change when we change one variable such as coil turns, wire gauge, insulation thickness, dielectric constant, coil shape (tall, short or narrow, wide), core shape, core material, core size and the list can go on as long as there is some measured difference from making the variable change.

Passive pickups work in a loaded environment that consists of the pickup volume pot together with the amplifier 1 meg ohm (typical) input impedance which results in a 200K ohms load for a typical single coil and a 400K ohms load for the typical Humbucker or P90 style pickup. This resistive load is external to the R of the pickup but affects and interacts with the LC of the pickup to reduce the height of the resonance peak and broaden the bandwidth somewhat. Now add about 350 pf to represent a typical 10 ft guitar coax cable and you now shift the resonance peak frequency to a lower value closer to a value in the 2Khz to 4 Khz range. Now add a 250K or 500K pot in series with a .02 uF capacitor (tone pot on 10) in parallel with this load and you have now fully simulated the typical loading of a passive pickup mounted in a traditionally wired guitar body with passive on-board volume and tone controls.

Question: Should graphs of pickups be depicted with the pickups being measured alone or should they be depicted as measured in the typical pickup environment with the appropriate loads as suggested above? I realize that showing differences caused changing variables listed above can cause different graphs but what will the ear hear when the loading effect causes some subtleties to blend together?

If subtleties are to be preserved, some form of active buffering needs to occur either right after the pickup and before the volume pot or at the guitar end of the cable with an active device in the cable plug presenting a 5 Meg Ohm to 10 Meg ohm load to the pickup and a few K Ohm output impedance to eliminate the cable capacitance effect on the passive pickup loading. I have tied this type of device and there is a clear difference in the effect of using active buffering on the resonance frequency and peak but the pleasure of this effect is highly subjective.

I hope forum members jump in and share their opinion on this matter.

Joseph J. Rogowski

[Antigua]

Question: Should graphs of pickups be depicted with the pickups being measured alone or should they be depicted as measured in the typical pickup environment with the appropriate loads as suggested above? I realize that showing differences caused changing variables listed above can cause different graphs but what will the ear hear when the loading effect causes some subtleties to blend together?

It depends on whether different pickups change proportionately to the differing LCR values, of it they change somewhat unpredictably. For example, some people have noticed that Lace Sensors don't roll off the tone the same as a true single coil, which suggests that making a Lace Sensor that sounds like a true single coil "in context", with typical guitar loads and capacitances, is not the same as making a Lace Sensor that sounds like a true single coil "out of context", hooked up directly to test equipment.

[Mike Sulzer]

If subtleties are to be preserved, some form of active buffering needs to occur either right after the pickup and before the volume pot or at the guitar end of the cable with an active device in the cable plug presenting a 5 Meg Ohm to 10 Meg ohm load to the pickup and a few K Ohm output impedance to eliminate the cable capacitance effect on the passive pickup loading.

There are no subtitles to preserve. The guitar speaker rolls off dramatically at about 5KZ, and so the high frequencies are irrelevant. The cable puts the resonance at the frequency where people want it, with the chosen value depending upon what the guitarist is doing, depending also of course on the inductance the pickup is wound to. There is nothing magic about using a very high impedance load so that the Q is not lowered. Some pickups are higher Q than others; you choose what you want. (Studying the pickup in terms of its natural resonance is useful, however.)

Also, it is not necessary to use an active buffer. One can buffer to a sufficiently high impedance with a resistor divider in the guitar and amplify outside the guitar at the other end of the cable with a low noise amplifier. (A noise voltage a factor of five lower than a 12AX7 is practical.)

[fieldwrangler]

To all members commenting on this thread.

When it comes to the evolution of things to be analyzed we tend to get down to the fundamental elements such as in humans it is the DNA but in guitar pickups it is the LCR. However, in LCR pickup analysis we are looking for how the response graph shapes change when we change one variable such as coil turns, wire gauge, insulation thickness, dielectric constant, coil shape (tall, short or narrow, wide), core shape, core material, core size and the list can go on as long as there is some measured difference from making the variable change.

Passive pickups work in a loaded environment that consists of the pickup volume pot together with the amplifier 1 meg ohm (typical) input impedance which results in a 200K ohms load for a typical single coil and a 400K ohms load for the typical Humbucker or P90 style pickup. This resistive load is external to the R of the pickup but affects and interacts with the LC of the pickup to reduce the height of the resonance peak and broaden the bandwidth somewhat. Now add about 350 pf to represent a typical 10 ft guitar coax cable and you now shift the resonance peak frequency to a lower value closer to a value in the 2Khz to 4 Khz range. Now add a 250K or 500K pot in series with a .02 uF capacitor (tone pot on 10) in parallel with this load and you have now fully simulated the typical loading of a passive pickup mounted in a traditionally wired guitar body with passive on-board volume and tone controls.

Question: Should graphs of pickups be depicted with the pickups being measured alone or should they be depicted as measured in the typical pickup environment with the appropriate loads as suggested above? I realize that showing differences caused changing variables listed above can cause different graphs but what will the ear hear when the loading effect causes some subtleties to blend together?

If subtleties are to be preserved, some form of active buffering needs to occur either right after the pickup and before the volume pot or at the guitar end of the cable with an active device in the cable plug presenting a 5 Meg Ohm to 10 Meg ohm load to the pickup and a few K Ohm output impedance to eliminate the cable capacitance effect on the passive pickup loading. I have tied this type of device and there is a clear difference in the effect of using active buffering on the resonance frequency and peak but the pleasure of this effect is highly subjective.

I hope forum members jump in and share their opinion on this matter.

Joseph J. Rogowski

Oh boy. Don't have the time for a detailed report on my opinion and perspective on this stuff, but let's just say for the moment that these issues are quite front & center for me at the moment.

Ultra short version is that when I've presented pickups with broad frequency response yet low internal damping in conjunction with user-adjustable resonance & damping controls (C & R) most players have no idea how to relate to it, and some claim to think that the controls aren't even connected and I'm playing a joke on them. It's almost enough to make me hate electric guitarists as a group, and I'm currently in the process of talking myself off the ledge about this.

On the other hand, when I present these setups to university jazz students in a quiet room plugged straight into a clean amp they just can't stop commenting on how different it feels to play the instrument with the knobs & switches in different positions.

I know this isn't really the question you asked but I just had to vent my frustration...

[Mike Sulzer]

Oh boy. Don't have the time for a detailed report on my opinion and perspective on this stuff, but let's just say for the moment that these issues are quite front & center for me at the moment.

Ultra short version is that when I've presented pickups with broad frequency response yet low internal damping in conjunction with user-adjustable resonance & damping controls (C & R) most players have no idea how to relate to it, and some claim to think that the controls aren't even connected and I'm playing a joke on them. It's almost enough to make me hate electric guitarists as a group, and I'm currently in the process of talking myself off the ledge about this.

On the other hand, when I present these setups to university jazz students in a quiet room plugged straight into a clean amp they just can't stop commenting on how different it feels to play the instrument with the knobs & switches in different positions.

I know this isn't really the question you asked but I just had to vent my frustration...

That was right on topic and very interesting.

[LtKojak]

I've presented pickups with broad frequency response yet low internal damping in conjunction with user-adjustable resonance & damping controls (C & R) most players have no idea how to relate to it, and some claim to think that the controls aren't even connected and I'm playing a joke on them. It's almost enough to make me hate electric guitarists as a group, and I'm currently in the process of talking myself off the ledge about this.

On the other hand, when I present these setups to university jazz students in a quiet room plugged straight into a clean amp they just can't stop commenting on how different it feels to play the instrument with the knobs & switches in different positions.

Yeah... guitar players... can't stand'em, can't kill'em!

Anyway, your average Rock guitar player is not listening to the frequencies you're proposing, they don't even hear the swooshing sound of going over their head! They do feel the air moving, although they just assume there's an open window somewhere. *sigh*

OTOH, your young Jazz guitar player is listening to the music and the guitar to its fully extent, hence why they do respond to the stimulus. However, I don't think the older Jazz player would respond either, being those frequencies out of their listening range. Also they're too "brand-indoctrinated", and would accept any shite as "it sounds as it should be" as long as it has the Gibson brand stamped on it and would unconsciously adapt their playing to fit the product. I see it constantly when people come asking for p'up advice in Jazz guitar forums: 80% would say " '57 Classic" as first choice, and even more if they're over fifty years old.

You'd be surprised the amount of times I get the "that's how a Gibson should sound like" when I'm playing my Korean L5-CES copy with an A3-modded Duncan APH1N. And not only that, they even refuse to believe it when told. They still think it's a '57 Classic!

Yeah... guitar players... can't stand'em, can't kill'em! *sigh*

HTH,

[fieldwrangler]

Yeah... guitar players... can't stand'em, can't kill'em!

Anyway, your average Rock guitar player is not listening to the frequencies you're proposing, they don't even hear the swooshing sound of going over their head! They do feel the air moving, although they just assume there's an open window somewhere. *sigh*

OTOH, your young Jazz guitar player is listening to the music and the guitar to its fully extent, hence why they do respond to the stimulus. However, I don't think the older Jazz player would respond either, being those frequencies out of their listening range. Also they're too "brand-indoctrinated", and would accept any shite as "it sounds as it should be" as long as it has the Gibson brand stamped on it and would unconsciously adapt their playing to fit the product. I see it constantly when people come asking for p'up advice in Jazz guitar forums: 80% would say " '57 Classic" as first choice, and even more if they're over fifty years old.

You'd be surprised the amount of times I get the "that's how a Gibson should sound like" when I'm playing my Korean L5-CES copy with an A3-modded Duncan APH1N. And not only that, they even refuse to believe it when told. They still think it's a '57 Classic!

Yeah... guitar players... can't stand'em, can't kill'em! *sigh*

HTH,

Thanks for this, Pepe.

Much of my past playing life was as a 50+ jazz guitar player, although I may be somewhat hypersensitive to these issues. However, I will say that my feeling about the significance of damping issues to players (almost none of which recognize them as such) revolve around response characteristics as opposed to spectral. For instance, the best straiight-ahead jazz guitarist in Chicago (who I believe is also over 50) refuses to play with the (uncompensated, I'm sure) volume control on his axe above 3, because he claims "there's less wood in the sound."

[Mike Sulzer]

Thanks for this, Pepe.

Much of my past playing life was as a 50+ jazz guitar player, although I may be somewhat hypersensitive to these issues. However, I will say that my feeling about the significance of damping issues to players (almost none of which recognize them as such) revolve around response characteristics as opposed to spectral. For instance, the best straiight-ahead jazz guitarist in Chicago (who I believe is also over 50) refuses to play with the (uncompensated, I'm sure) volume control on his axe above 3, because he claims "there's less wood in the sound."

When he does that the RC constant of volume/cable system is flat past frequencies he is using (low enough source impedance) and the resonance of the pickup moves up to its natural value (without cable) which is also typically well above 5 KHz and outside the bandpass of the speaker. He wants flat response, apparently, with the ability to take it down further with the tone control. He also gets a constant tonal response when changing the volume as long as it does not go up too many numbers.

Playing with the volume down is a simple way to isolate the guitar from the cable. Add switchable capacitors across the pickups and you have a wide variety of sounds. Add a low noise preamp outside the guitar and you can even do it with high gain. Put a volume pedal in your effects loop and you have flexible control over how hard you drive the amp preamp with the guitar volume controls and the level of the sound with the volume pedal, and you can "preset" two very different sounds with the two pickups if each pickup has its own volume control and you are willing to use the volume pedal as you change.

[fieldwrangler]

All absolutely true, as regards both my knowledge and experience.

Much of my frustration and disorientation results from how much resistance I often encounter when trying to VERY GENTLY AND SPECIFICALLY introduce players to the idea that many of the tonal attributes they're pursuing can be more successfully accessed by thinking about things in terms of resonance & damping, combined with an understanding about how these exist in often hidden ways inside of the world of pickups, controls, cables, stomp boxes, preamps, power amps, speakers, cabs, rooms, mics, etc.

When making custom stuff this can work out very well through demonstrations and passing axes back & forth. Now that I'm in the process of finalizing a commercial design or two I see a lot of the more radical attributes of my custom stuff fading away and being replaced by parameters that look disappointingly like a whole bunch of other stuff out there.

I may yet find a way to avoid this. I'm not really buying into a "wisdom of crowds" approach at the moment, but I do see how the ecosystem of existing amps, speakers, etc., combined with the way in which many players have explained their tone formulas has resulted in a certain narrow box into which most pickups are made to fit.

[elipsey]

May I ask what effect the composition of steel used in pickup parts might have on the sound of the pickup?

It seems like for beginner hobbyist types (like me) humbucker pole pieces, screws, and keepers are mostly available in 1018 and 1022. Is there generally a pattern of interest in the behavior of these parts as the alloy number increases, e.g. bigger number = more carbon = more eddy currents = less treble, or something, that can be used any sort of a rule of thumb for the effect of the alloy on sound?

To avoid at least some of the "it depends" part of the answer, let's assume 5000 turns per coil, 500k pots, and a medium length cable plugged straight into a tube amp that doesn't have extremely high input impedance -- make it a 5F2A, why not?

(By the way, at the risk of being pelted with rocks and garbage, I will admit that I think '57 Classics are rather nice sounding. Maybe you guys just mean there's room for more than one pickup in the world...)

[ScottA]

May I ask what effect the composition of steel used in pickup parts might have on the sound of the pickup?

It seems like for beginner hobbyist types (like me) humbucker pole pieces, screws, and keepers are mostly available in 1018 and 1022. Is there generally a pattern of interest in the behavior of these parts as the alloy number increases, e.g. bigger number = more carbon = more eddy currents = less treble, or something, that can be used any sort of a rule of thumb for the effect of the alloy on sound?

To avoid at least some of the "it depends" part of the answer, let's assume 5000 turns per coil, 500k pots, and a medium length cable plugged straight into a tube amp that doesn't have extremely high input impedance -- make it a 5F2A, why not?

(By the way, at the risk of being pelted with rocks and garbage, I will admit that I think '57 Classics are rather nice sounding. Maybe you guys just mean there's room for more than one pickup in the world...)

Actually it's less carbon = more eddy currents, in general.

Permeability goes up significantly as carbon content decreases. Conductivity also increases with decreasing carbon content, but it is a weaker function.

And yes, '57 Classics do sound pretty good.

[Tony Bones]

Oh boy. Don't have the time for a detailed report on my opinion and perspective on this stuff, but let's just say for the moment that these issues are quite front & center for me at the moment.

Ultra short version is that when I've presented pickups with broad frequency response yet low internal damping in conjunction with user-adjustable resonance & damping controls (C & R) most players have no idea how to relate to it, and some claim to think that the controls aren't even connected and I'm playing a joke on them. It's almost enough to make me hate electric guitarists as a group, and I'm currently in the process of talking myself off the ledge about this.

On the other hand, when I present these setups to university jazz students in a quiet room plugged straight into a clean amp they just can't stop commenting on how different it feels to play the instrument with the knobs & switches in different positions.

I know this isn't really the question you asked but I just had to vent my frustration...

So-called "50's wiring" just changes the loading on the pickup compared to "modern" wiring. Some electric guitarist love it because it offers a greater array of tones. Some guitarists find it confusing so stick with modern wiring because they understand which way to turn the knobs to get closer to the sound they want.

You just need to find the right electric guitarists!

[fieldwrangler]

May I ask what effect the composition of steel used in pickup parts might have on the sound of the pickup?

It seems like for beginner hobbyist types (like me) humbucker pole pieces, screws, and keepers are mostly available in 1018 and 1022. Is there generally a pattern of interest in the behavior of these parts as the alloy number increases, e.g. bigger number = more carbon = more eddy currents = less treble, or something, that can be used any sort of a rule of thumb for the effect of the alloy on sound?


To avoid at least some of the "it depends" part of the answer, let's assume 5000 turns per coil, 500k pots, and a medium length cable plugged straight into a tube amp that doesn't have extremely high input impedance -- make it a 5F2A, why not?

(By the way, at the risk of being pelted with rocks and garbage, I will admit that I think '57 Classics are rather nice sounding. Maybe you guys just mean there's room for more than one pickup in the world...)

I just profiled a pickup comparing 1010 & 1018 (or so they're specified when sold) slugs and got EXACTLY THE SAME IMPEDANCE CURVES. The test rig seems fine, as I can clearly see the difference between two coils with a couple hundred turns difference.

Today we listen...

[charrich56]

Guys,

What a frightening (8-)) combination of intelligence, experience, and willingness to share knowledge and experiment we're seeing on this thread. I have an enormous respect gained over several years for a lot of the people who have been commenting so far.

So here's a question since there are some heavy hitters in the room here:

Do you think that the magnetic characteristics you are discussing (remanence, coercivity, eddy losses, etc.) of the poles, magnets, magnetic structure, etc. in the pickup are nonlinear in the interaction between string and magnetic field, and complex coil impedance, and therefore not easily reproducible by downstream signal processing, or are they in your opinion, linear filtering effects that can be separated out by magnetic circuit, coil effects, etc. which can just be added in or changed by X stages of analog or digital filters downstream?

[LtKojak]

Guys,

What a frightening (8-)) combination of intelligence, experience, and willingness to share knowledge and experiment we're seeing on this thread. I have an enormous respect gained over several years for a lot of the people who have been commenting so far.

So here's a question since there are some heavy hitters in the room here:

Do you think that the magnetic characteristics you are discussing (remanence, coercivity, eddy losses, etc.) of the poles, magnets, magnetic structure, etc. in the pickup are nonlinear in the interaction between string and magnetic field, and complex coil impedance, and therefore not easily reproducible by downstream signal processing, or are they in your opinion, linear filtering effects that can be separated out by magnetic circuit, coil effects, etc. which can just be added in or changed by X stages of analog or digital filters downstream?

In a nutshell, no.

HTH,