Does anyone make a HB with mismatched coils....

[Teleplayer]

Re: Does anyone make a HB with mismatched coils....

Interactions between the coils doesn't lower the Q (unless you split the humbucker, but that's another story), and that's the case regardless of whether the coils are matched or not.

Have you proved this with otherwise equally wound humbucker? Eg: humbucker assembled from 2x Fred Bridge coils, or 2x Fred Inside coils. To me its reasonable that mismatch in resonance frequency will exercise increased eddy current losses in the metal components.

Keep in mind that DiMarzio's patent stipulates that both coils have the same numbers of turns per coil, but different wire gauges, so they coils are not effectively mismatched at all. Because both coils have the same number of turns, they will have similar inductances and produce near identical voltage output. In fact, a regular P.A.F. having one coil with slugs, and one with screws, constitutes a greater coil mismatch than simply having used two different wire gauges. The difference you get from using thinner wire for one coil represents a trivial amount of series resistance, which you can measure yourself, and is the same as if you had put a 1k ohm resistor in series with one of the coils of a regular P.A.F. type pickup.

I expect the capacitance will be higher with a coil wound from a thinner wire. You make a good point about slugs and screws - That should have been pointed out in this thread (even though it does not apply to the S.D.). Its really true that conventional humbuckers are mismatched due to this, whereas the double screw types avoid it.

That's a rather small difference in DC resistance. They could have identical turn counts per coil and you might still see that amount of difference in DC resistance.

For a pickup with good quality control the difference is normally less. Also it seems to be consistent across a few sets of measurements I have seen for the PAF PRO.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

Have you proved this with otherwise equally wound humbucker? Eg: humbucker assembled from 2x Fred Bridge coils, or 2x Fred Inside coils. To me its reasonable that mismatch in resonance frequency will exercise increased eddy current losses in the metal components.

I'm not sure what gives rise to this line of thinking. Eddy currents impact the resonance, not the other way around. Specifically, eddy currents reduce the Q factor. This is not only true of guitar pickups, but in inductors and transformers, which is why they often have laminated, or non conductive cores when low eddy current losses, or a high Q factor is required.

I expect the capacitance will be higher with a coil wound from a thinner wire. You make a good point about slugs and screws - That should have been pointed out in this thread (even though it does not apply to the S.D.). Its really true that conventional humbuckers are mismatched due to this, whereas the double screw types avoid it.

It's hard to say where the capacitance will end up. The thinner wire has a smaller surface area, but the insulation thickness will vary between them also, and one coil might be wound tighter than the other. It tends to be a toss up, and in any event, this parasitic capacitance is rather small, especially compared to the guitar cable capacitance.

For a pickup with good quality control the difference is normally less. Also it seems to be consistent across a few sets of measurements I have seen for the PAF PRO.

They might have slightly different wind counts, but for all the reasons mentioned prior, it's neither here nor there.

 

[Teleplayer]

Re: Does anyone make a HB with mismatched coils....

I'm not sure what gives rise to this line of thinking. Eddy currents impact the resonance, not the other way around. Specifically, eddy currents reduce the Q factor. This is not only true of guitar pickups, but in inductors and transformers, which is why they often have laminated, or non conductive cores when low eddy current losses, or a high Q factor is required.

EDITED VERSION:
My thinking is along the lines of phase shift due to differently tuned coils. For the unblanced humbucker, each coil will have slightly different inductance and capacitance. I am thinking about complex phase angles of impedance which is an electrical engineering concept. When operating at frequencies below its open circuit resonance frequency, the lower tuned coil will have a smaller reactive component in its impedance than the higher tuned coil. IOW, as the lower tuned coil approaches its open circuit resonance frequency its impedance becomes increasingly like a resistor due to the effect of parallel LC resonance. In the same frequency range, the higher tuned coil has an impedance that is more like an inductor. Due to interaction of the series connection of two coils with unbalanced impedances, the currents flowing though each coil will not be exactly in phase. Phase shift of the current through each coil creates an component of the magnetic field in each coil of the humbucker that is out of phase with the change in flux from the string movement. How the out of phase magnetic field translates into eddy losses or change in Q is where I need to work harder to analyse! I am also not sure to what magnitude the effect would occur and whether its significant or not.

They might have slightly different wind counts, but for all the reasons mentioned prior, it's neither here nor there.

I just checked my notes for PAF PRO. The difference is higher than some other examples i have read about.

Inside coil (Red-Black) = 4.50k
Bridge coil (white-Green) = 4.18k

I wonder if there may be some subtle difference to wire spec, or the winding tension.

 

[Mincer]

Re: Does anyone make a HB with mismatched coils....

I have to thank all of you for these interesting discussions. I wind up learning a lot from things like this.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

The inductances of the two coils sum to form a single inductance value that dominates the overall circuit, including the guitar cable and other stray capacitances. The self resonance of the coils that is caused by their isolation from one another is at a frequency that is higher than the dominant resonance of the two inductances combined. Since the amplitude drops off above the dominant resonance, which is of a lower frequency, those smaller, higher frequency resonances are never audibly realized.

If this were 100% the case you would hear no decernable difference audibly in regards to orientation of these pickups, especially in the models with identical amount of ferrous material in each bobbin.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

EDITED VERSION:
My thinking is along the lines of phase shift due to differently tuned coils. For the unblanced humbucker, each coil will have slightly different inductance and capacitance. I am thinking about complex phase angles of impedance which is an electrical engineering concept. When operating at frequencies below its open circuit resonance frequency, the lower tuned coil will have a smaller reactive component in its impedance than the higher tuned coil. IOW, as the lower tuned coil approaches its open circuit resonance frequency its impedance becomes increasingly like a resistor due to the effect of parallel LC resonance. In the same frequency range, the higher tuned coil has an impedance that is more like an inductor. Due to interaction of the series connection of two coils with unbalanced impedances, the currents flowing though each coil will not be exactly in phase. Phase shift of the current through each coil creates an component of the magnetic field in each coil of the humbucker that is out of phase with the change in flux from the string movement. How the out of phase magnetic field translates into eddy losses or change in Q is where I need to work harder to analyse! I am also not sure to what magnitude the effect would occur and whether its significant or not.



I just checked my notes for PAF PRO. The difference is higher than some other examples i have read about.

Inside coil (Red-Black) = 4.50k
Bridge coil (white-Green) = 4.18k

I wonder if there may be some subtle difference to wire spec, or the winding tension.

Your reasoning does seem plausible or at very least partially. Regarding the paf pro, I do have a few kicking around I could measure to see if this is uniform from pick to pickup. If it’s intentional it would most likely be somewhat uniform from unit to unit.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

If this were 100% the case you would hear no decernable difference audibly in regards to orientation of these pickups, especially in the models with identical amount of ferrous material in each bobbin.

I'm not following what you're saying, but I can assure you that what I'm telling you is consistent with well worn principles of circuit analysis.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

As this pic comes from me, I’ll add a minimalist comment.

This screenshot was a snippet illustrating non finalized experimental results, surely picked somewhere in my archived data and posted to answer in a defined context (I don’t even remember in which topic nor when).

If I had to use again this screenshot, I’d rather put it a topic about SC sized stacks. The measurements done here about HB’s are different, especially those involving dual resonance DiMarzio’s.

Also and FWIW: a minor mod on the Kinman mentioned in my picture would suffice to give it a distinct dual resonant peak, absolutely audible in a played guitar. This mod (involving only stock parts with no added components) has already been tried here.

So, even if I understand what you say and find it logical, my experience is more on par with what JoeyVoltage says.

Speak of the devil, I found a post where you had talked about Gibson doing the very thing we're discussing here, capacitance to ground in between the two coils: https://forum.seymourduncan.com/sho...uot-coil-tap&p=3810625&viewfull=1#post3810625

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

EDITED VERSION:
My thinking is along the lines of phase shift due to differently tuned coils. For the unblanced humbucker, each coil will have slightly different inductance and capacitance. I am thinking about complex phase angles of impedance which is an electrical engineering concept. When operating at frequencies below its open circuit resonance frequency, the lower tuned coil will have a smaller reactive component in its impedance than the higher tuned coil. IOW, as the lower tuned coil approaches its open circuit resonance frequency its impedance becomes increasingly like a resistor due to the effect of parallel LC resonance. In the same frequency range, the higher tuned coil has an impedance that is more like an inductor. Due to interaction of the series connection of two coils with unbalanced impedances, the currents flowing though each coil will not be exactly in phase. Phase shift of the current through each coil creates an component of the magnetic field in each coil of the humbucker that is out of phase with the change in flux from the string movement. How the out of phase magnetic field translates into eddy losses or change in Q is where I need to work harder to analyse! I am also not sure to what magnitude the effect would occur and whether its significant or not.

You're saying the phase angle would vary because "its impedance becomes increasingly like a resistor", but it doesn't actually become a resistor, it's still a reactance, and the real resistance is still a fixed value, so the phase angle remains the same.

The non ideal factors at hand, real resistance, parasitic capacitance, mutual inductance and eddy currents are not substantial enough to create two distinctly audible resonant peaks, regardless of how unalike the inductors are. In order to do that, you have to put a high capacitance between the inductors. In the course of doing some searching, I found that Gibson has already done this http://www.gibson.com/News-Lifestyle/Gear-Tech/en-us/Tuned-Coil-Tap-aspx.aspx , this is the correct way to do what DiMarzio claims their patent should do.

I just checked my notes for PAF PRO. The difference is higher than some other examples i have read about.

Inside coil (Red-Black) = 4.50k
Bridge coil (white-Green) = 4.18k

I wonder if there may be some subtle difference to wire spec, or the winding tension.

My PAF Pro shows a similar disparity, but the inductances I measure for each are near identical, so I have to assume it's an issue with the wire, and not the turn counts.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

I'm not following what you're saying, but I can assure you that what I'm telling you is consistent with well worn principles of circuit analysis.

What i'm saying is that if the dual resonance concept is inaudible bologna, and you end up with a single composite dominant resonance frequency, especially in a pickup with symmetrical pole configuration on both bobbins, logic would have it that you shouldn't be able flip the pickup around for a distinctly different frequency characteristics, which is another DiMarzio claim regarding the dual resonance patent. Oddly enough, many of their pickups under this patent do so. Many users of these products can assure you that this does indeed happen as well. This should not happen if in the reality of dual resonance, you just end up with one dominant resonance frequency with a little bit of inaudible overshoot on the tail end. Pickups such as the steve's special should not exist.

For the record I have no idea what dimarzio actually does in practice or how closely their pickups follow whats outlined in the original patent.

You're saying the phase angle would vary because "its impedance becomes increasingly like a resistor", but it doesn't actually become a resistor, it's still a reactance, and the real resistance is still a fixed value, so the phase angle remains the same.
.

I don't think he's quite saying that nor is he describing anything to the contrary to the general concept of reactance, but I'll let him speak for himself.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

What i'm saying is that if the dual resonance concept is inaudible bologna, and you end up with a single composite dominant resonance frequency, especially in a pickup with symmetrical pole configuration on both bobbins, logic would have it that you shouldn't be able flip the pickup around for a distinctly different frequency characteristics, which is another DiMarzio claim regarding the dual resonance patent. Oddly enough, many of their pickups under this patent do so.

Because the coil wound with 42 AWG is slightly larger, there is a chance that it will produce slightly more voltage than the 43 AWG coil, which has a smaller width, but the difference is going to be very tiny, because the vast majority of the flux change happens down the middle of the coil, where you have a highly permeable screw. The outter reaches of the coil are much less involved, so making a coil wider with thicker wire, or by using a flatter bobbin, makes very little difference.

The difference in output voltage is small, but on top of that, the coils are so close together that reversing their positions under the guitar strings wouldn't change the harmonic content much at all. You'd get a more significant difference in the bridge/neck combo sound if you traded around the bridge and neck pickups, because now you're swapping voltage sources that are a couple inches apart, instead of two that are directly side by side. You need a serious difference in harmonic content in order to hear any real change if you're varying the voltage output between them.

Many users of these products can assure you that this does indeed happen as well. This should not happen if in the reality of dual resonance, you just end up with one dominant resonance frequency with a little bit of inaudible overshoot on the tail end. Pickups such as the steve's special should not exist.

People believe their stereos sound better when they used gold plated connectors. Ear-witness testimony, if you will, cannot be relied upon in the field of audio.

I viewed the product page for Steve's Special. I see no mention of re-orienting the pickup for a different tone, I just see the same unsubstantiated claims about "dual resonance".

For the record I have no idea what dimarzio actually does in practice or how closely their pickups follow whats outlined in the original patent.

They follow the patent more or less to the letter, with two coils using different wire gauges but similar, if not identical, turn counts. Keep in mind that just because a patent says something is so, doesn't mean it is so. The content therein only has to be convincing enough for a patent examiner to OK it. The patent examiner isn't going to create the thing in a laboratory and verify that everything happens as claimed.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

People believe their stereos sound better when they used gold plated connectors. Ear-witness testimony, if you will, cannot be relied upon in the field of audio.

Oh, I’m well aware. I deal with more of my share of this in other aspects of diy audio. Trust me, I’m one of the biggest skeptics out there when it comes to things of that nature.

I viewed the product page for Steve's Special. I see no mention of re-orienting the pickup for a different tone, I just see the same unsubstantiated claims about "dual resonance".

It was on their sight once upon a time, maybe under the faq section. They usually revise their site from time to time so I’m not sure where or if mention of that is still there. Having owned it, The Steve’s special does behave rather funky in this regard.

They follow the patent more or less to the letter, with two coils using different wire gauges but similar, if not identical, turn counts. Keep in mind that just because a patent says something is so, doesn't mean it is so. The content therein only has to be convincing enough for a patent examiner to OK it. The patent examiner isn't going to create the thing in a laboratory and verify that everything happens as claimed.

I’m well aware of the various techniques used to game the uspto. fwiw I did just sim a hypothetical model and it indeed shows quite a pronounced secondary resonance frequency that basically looks like high frequency overshoot due to how narrow the q is. What is interesting about it is that it has a slightly more gentle db per decade slope at hf, before it rises right back up due to the secondary resonance frequency. I am inclined to believe the dual resonance objective is at least partly true. Maybe I’ll post the plots up later. I might just dissect one of their pickups with the 4501 patent so I can work with real numbers and have a more reliable sim.

 

[freefrog]

Re: Does anyone make a HB with mismatched coils....

Speak of the devil, I found a post where you had talked about Gibson doing the very thing we're discussing here, capacitance to ground in between the two coils: https://forum.seymourduncan.com/sho...uot-coil-tap&p=3810625&viewfull=1#post3810625

Why "speak of the devil"? ,-)

Quick morning answer before a busy day:

-IMHE, there's a world to explore in LRC components creating dual resonance or shifting the resonant peak in a useable way once associated with pickups (in between coils, in parallel, in series). I've done such things for a touring pro and he's constantly using my circuits on stage:

-now, that's not what I was talking about with the mod doable on the Kinman (but I won't dig it here since it involves proprietary information).

I did just sim a hypothetical model and it indeed shows quite a pronounced secondary resonance frequency that basically looks like high frequency overshoot due to how narrow the q is. What is interesting about it is that it has a slightly more gentle db per decade slope at hf, before it rises right back up due to the secondary resonance frequency. I am inclined to believe the dual resonance objective is at least partly true.

That's also my feeling on the basis of the experiments done here. I've various measurments in my archves about the dual resonance thing. Maybe I'll post a few samples later if time permits.

I wish you all a nice day.

 

[Hellion]

Re: Does anyone make a HB with mismatched coils....

....but NOT like a duncan hybrid where they are wound with different gauges. In other words, both coils are would with the same wire but one is wound lower. Or is that even design that could work? I realize it'll be noisier. I'm asking because i have been thinking of taking one of my dimarzio super D's and unwinding the screw coil from 7k down to 4 or 5k to lower the pickup's output while leaving the slug coil the same so it splits as well as it does now. I love super D's but i'd like less output without affecting the split sound and maybe the pickup would generate some interesting tones like the 59/hybrid does. I just don't know if this is a design that would be faulty given the same gauge on both but i thought i'd ask if there are any winders making something like that so i'd know it could be worth a shot.

Gibson's Burstbucker pickup might be what you're looking for. It's a coil dominant pickup, and I don't remember the specs, but I remember hearing about it 10+ years ago.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

Why "speak of the devil"? ,-)

Quick morning answer before a busy day:

-IMHE, there's a world to explore in LRC components creating dual resonance or shifting the resonant peak in a useable way once associated with pickups (in between coils, in parallel, in series). I've done such things for a touring pro and he's constantly using my circuits on stage:

-now, that's not what I was talking about with the mod doable on the Kinman (but I won't dig it here since it involves proprietary information).
.

You could even go further if you are willing to use some mild active circuitry, and make the resonance frequency between the coils sweepable.

Another thing you could do if you went full active is that you could dampen the self resonance of the coils completely, and then use gyration to add one any where you want, or make it sweep-able for each coil. doing it in this fashion wont have the same drastic reduction in high frequency response after the peak as a typical pickup does, although you may want some high end de-emphasis above 7-10khz. I think some companies of active pickups are doing this very thing, and marketing the product as one that dumps the muddiness associated with passive pickups.

 

[blueman335]

Re: Does anyone make a HB with mismatched coils....

What about it?

Last I knew you were in North Hollywood.

 

[Zhangliqun]

Re: Does anyone make a HB with mismatched coils....

Last I knew you were in North Hollywood.

Yes, I left CA behind last March. Cost of living too high, can't walk a block down the street there anymore without getting a contact high.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

I’m well aware of the various techniques used to game the uspto. fwiw I did just sim a hypothetical model and it indeed shows quite a pronounced secondary resonance frequency that basically looks like high frequency overshoot due to how narrow the q is. What is interesting about it is that it has a slightly more gentle db per decade slope at hf, before it rises right back up due to the secondary resonance frequency. I am inclined to believe the dual resonance objective is at least partly true. Maybe I’ll post the plots up later. I might just dissect one of their pickups with the 4501 patent so I can work with real numbers and have a more reliable sim.

Without knowing much of the details of how you're hypothetical model (that's a can of worms unto itself), keep in mind that in a typical electric guitar, the volume and tone pots introduce a significant load, while the guitar cable introduces a significant capacitance. I saw 7kHz-10kHz mentioned above, the cable capacitance is generally so high, around 400pF, give or take, that you don't realistically see harmonic content extending up much past 4kHz. Then when it comes to tiny resonances, such as the self resonance of a coil, you might see such things in a no load experiment, but once you put 250k or 125k across the inductor(s), large resonances are greatly diminished and small resonances disappear entirely.

The Gibson "tuned coil tap" goes to show that if you truly want two useful resonance peaks that create a valley, or a band stop in between them, you need to introduce a lot of capacitance, an amount that can only be had by way of an actual capacitor. About 1nF is the minimum you can go, and it would be rather tricky to get a coil to achieve 1nF worth of intrinsic capacitance in a coil. Gibson used a 10nF cap, and when I've tried this mod, 1nF had a nice but subtle effect, 10nF made an obvious difference. Mismatching wire gauges and other cute things like that doesn't allow for outcomes like this, from a circuit topology standpoint.

 

[Joey Voltage]

Re: Does anyone make a HB with mismatched coils....

Without knowing much of the details of how you're hypothetical model (that's a can of worms unto itself), keep in mind that in a typical electric guitar, the volume and tone pots introduce a significant load, while the guitar cable introduces a significant capacitance. I saw 7kHz-10kHz mentioned above, the cable capacitance is generally so high, around 400pF, give or take, that you don't realistically see harmonic content extending up much past 4kHz. Then when it comes to tiny resonances, such as the self resonance of a coil, you might see such things in a no load experiment, but once you put 250k or 125k across the inductor(s), large resonances are greatly diminished and small resonances disappear entirely.

The Gibson "tuned coil tap" goes to show that if you truly want two useful resonance peaks that create a valley, or a band stop in between them, you need to introduce a lot of capacitance, an amount that can only be had by way of an actual capacitor. About 1nF is the minimum you can go, and it would be rather tricky to get a coil to achieve 1nF worth of intrinsic capacitance in a coil. Gibson used a 10nF cap, and when I've tried this mod, 1nF had a nice but subtle effect, 10nF made an obvious difference. Mismatching wire gauges and other cute things like that doesn't allow for outcomes like this, from a circuit topology standpoint.

Yes it was loaded with 500k and about 470pf-680pf for cable capacitance I even went up to 1nf. I really wanted to ignore the effects of the tone control for this. I also did try the Gibson method while I was at it, and it didn’t look too dissimilar. The trick though is that the inductance of the two coils does have to be somewhat dissimilar, which is easily done in such models that use that big slug blade in one coil or that use the virtual vintage, or any methods to shove more ferrous core material with in the bobbin. Part of me thinks that on models that have pretty dissimilar wire gauges like the Steve’s special where one coil is most likely 6k worth of 43, and the other is 12k worth of something stupidly thin, that the turn count on each coil is asymmetric as well. This pickup too is one with the aforementioned scooped sound as well, especially for a pickup that’s made the way it is.

 

[PicoRiveraTele]

Re: Does anyone make a HB with mismatched coils....

Yes it was loaded with 500k and about 470pf-680pf for cable capacitance I even went up to 1nf. I really wanted to ignore the effects of the tone control for this. I also did try the Gibson method while I was at it, and it didn’t look too dissimilar. The trick though is that the inductance of the two coils does have to be somewhat dissimilar, which is easily done in such models that use that big slug blade in one coil or that use the virtual vintage, or any methods to shove more ferrous core material with in the bobbin. Part of me thinks that on models that have pretty dissimilar wire gauges like the Steve’s special where one coil is most likely 6k worth of 43, and the other is 12k worth of something stupidly thin, that the turn count on each coil is asymmetric as well. This pickup too is one with the aforementioned scooped sound as well, especially for a pickup that’s made the way it is.

Regarding your seeing two distinct (and useful) resonances with inductors of differing values is something I'd have to see to believe. When you put two impedances in series, they add together, and as mentioned above, the difference in parasitic capacitance between them would have to be astronomical for a pickup coil, in order for it to serve the purpose here. The added ferrous core materials only provide a tiny boost in inductance, because as high as their permeability might be, the majority of the core itself is air, and the vast majority of the magnetic circuit, as a whole, is air. It would be similar to making an inductor's core slightly longer. On top of that, DiMarzio puts these things in both coils, so the boost will be symmetrical. And on top of that, the way the patent is worded, with "same number of turns" of wire per coil is going out of their way to make sure the inductances are close. If diverging inductances are the secret recipe, then the patent would be shooting itself in the foot by the second sentence.

You can say a pickup sounds "scooped", but everyone says that about the '59 model, and it's using no such coil imbalances. People's ears aren't a suitable stand in for an actual response analysis.