Wah Inductors. No hype. Just measurements.
- Thread starter Stickman393
- Start date
Stickman393
Well-known member
That's generally been the case with stock mounts for me too; I've collected a few that work well in certain situations, but for the most part moving forward I'll be making mine with custom mounts.
The mounts for these, especially the pot cores, can get real pricy real quick. I'm having to get creative with the way I do my own.
I've just completed winding three new cores with my new roll of Litz wire. I gotta say...it's much easier to work with than the stuff I was using before. More flexible, less likely to break. Its thicker, so it lays down easier, but I'm still getting like 40 ohms from a completed nominal 525mH coil.
The experiment here was to track my progress in programming the coil winder. #1 was *way* off and resulted in a coil that was heavily scatter wound. So....lemonade, bitches. #2 was less scatter wound, #3 had minimal to no scatter winds.
I'll be assembling them today and doing a comparison. There are still variables here that I can't quite account for: clamping force is still a beyond my current abilities to measure, and there will be some natural variation in the cores. But, in theory, scatter winding will have two impacts: a decrease in parasitic capacitance, and a decrease in inductance.
Will I be able to observe that? Dunno. Too many unaccounted for variables. Plus, I'm just a guitar player banging rocks together. Who is also a literal stick man.
The mounts for these, especially the pot cores, can get real pricy real quick. I'm having to get creative with the way I do my own.
I've just completed winding three new cores with my new roll of Litz wire. I gotta say...it's much easier to work with than the stuff I was using before. More flexible, less likely to break. Its thicker, so it lays down easier, but I'm still getting like 40 ohms from a completed nominal 525mH coil.
The experiment here was to track my progress in programming the coil winder. #1 was *way* off and resulted in a coil that was heavily scatter wound. So....lemonade, bitches. #2 was less scatter wound, #3 had minimal to no scatter winds.
I'll be assembling them today and doing a comparison. There are still variables here that I can't quite account for: clamping force is still a beyond my current abilities to measure, and there will be some natural variation in the cores. But, in theory, scatter winding will have two impacts: a decrease in parasitic capacitance, and a decrease in inductance.
Will I be able to observe that? Dunno. Too many unaccounted for variables. Plus, I'm just a guitar player banging rocks together. Who is also a literal stick man.
So, will a thicker wire need less winds to get it to the required mh?
For example, i found one online tutorial to build an inductor using a wah inductor kit (pot core n48, bobbin etc) using 38awg wire and it needed about 500 winds approx to get to around 500mh.
Would thicker wire need less winds or more?
Stickman393
Well-known member
In my experience...well, it all depends.
Inductance is proportional to the square of the number of turns. This is how I've made small adjustments while winding my own cores, but there are other factors to consider as well.
The clamping pressure with which the cores are held together will impact your final measured value. How well the cores align will also have a huge impact.
I believe the ferrite variety that they sell with those kits is the N48. If that's the case, 500 winds is probably about right. Doesn't matter if it's 38, 40, etc.
But...in my experience, the way the core is wound also matters. Several factors interplay here: scatter winding appears to lead to a core with a lower Q and decreased inductance (though...hard to say on that last bit, as these cores tend to have about a 20% tolerance, and the differences I've observed are well within that range). Which makes sense: scatter winding positions the wraps further away from each other, where their individual magnetic fields don't have as much strength.
But...in the case of perfectly straight and aligned coils: having those wires in close proximity to each other also means that their individual electrical fields will have a greater impact between winds, creating parasitic capacitance, which also shows up as a lower measured inductance value. But I've found this to impact the end result less than scatter winding.
Thinner wire will have more resistance over its length. My favorite inductors have had DCR values of around 30-60 ohms...toroids tend to be around the 10-20 range in my experience.
Resistance will influence Q. Greater resistance=lower Q, and vice versa. Some manufacturers will put resistors in series with the inductor to bring down Q...this is the case with the Ernie ball wah, a pedal that absolutely did not need its Q to be tamed. This is also how the 535Q controls Q.
Now...you might be thinking...wait! Isn't the Increasing "vocal mod" performed by increasing resistance?
Well...sure. But that's a parallel path around the inductor. Increase the resistance there, and you force more current through the inductors path. Resistors don't really have a Q factor: they can only influence the Q factor of reactive components like inductors or capacitors.
Granted, treat the above information for what it is: the musings of a dude who is performing extremely unscientific experiments and barely understanding the stuff that he reads about those things that an electrician once told me he didn't believe in. Ahhhh...oh! Electrons. That's right.
Inductance is proportional to the square of the number of turns. This is how I've made small adjustments while winding my own cores, but there are other factors to consider as well.
The clamping pressure with which the cores are held together will impact your final measured value. How well the cores align will also have a huge impact.
I believe the ferrite variety that they sell with those kits is the N48. If that's the case, 500 winds is probably about right. Doesn't matter if it's 38, 40, etc.
But...in my experience, the way the core is wound also matters. Several factors interplay here: scatter winding appears to lead to a core with a lower Q and decreased inductance (though...hard to say on that last bit, as these cores tend to have about a 20% tolerance, and the differences I've observed are well within that range). Which makes sense: scatter winding positions the wraps further away from each other, where their individual magnetic fields don't have as much strength.
But...in the case of perfectly straight and aligned coils: having those wires in close proximity to each other also means that their individual electrical fields will have a greater impact between winds, creating parasitic capacitance, which also shows up as a lower measured inductance value. But I've found this to impact the end result less than scatter winding.
Thinner wire will have more resistance over its length. My favorite inductors have had DCR values of around 30-60 ohms...toroids tend to be around the 10-20 range in my experience.
Resistance will influence Q. Greater resistance=lower Q, and vice versa. Some manufacturers will put resistors in series with the inductor to bring down Q...this is the case with the Ernie ball wah, a pedal that absolutely did not need its Q to be tamed. This is also how the 535Q controls Q.
Now...you might be thinking...wait! Isn't the Increasing "vocal mod" performed by increasing resistance?
Well...sure. But that's a parallel path around the inductor. Increase the resistance there, and you force more current through the inductors path. Resistors don't really have a Q factor: they can only influence the Q factor of reactive components like inductors or capacitors.
Granted, treat the above information for what it is: the musings of a dude who is performing extremely unscientific experiments and barely understanding the stuff that he reads about those things that an electrician once told me he didn't believe in. Ahhhh...oh! Electrons. That's right.
Stickman393
Well-known member
Also: I'd say that yellow fasel is absolutely salvageable. Just need to get a bit of magnet wire, twist the end together with the one there, solder, insulate (nylon/kapton/polyamide tape is nice and thin and would do the trick), then wrap around the post, solder, and you're good.
Like so:
Like so:
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Stickman393
Well-known member
A'ite, I've recently picked up an old transition Italian crybaby. This was manufactured for a short time between 1967-1968, after the "script" box Clyde McCoy/top logo crybaby, but before the V846 and 95-blah blah blah. It contains an inductor that is quite unique in comparison to the others I've seen.
This has been dubbed the "clover leaf" inductor by the vintage pedal crowd. Not much information out there on them, and certainly not quite as desirable as the better-known "halo" or "trash can" inductors.
That said...judging by all the different Italian wah circuit boards I've seen over the years, I have to ask the question:
I'm beginning to suspect that there *may* not be all that much difference between the halo, the clover leaf, the film can. Or, rather, is there is enough variance between individual examples to make the categorization less meaningful than one might initially suspect.
Why do I suspect that? Because all the other parts on the various Jen and earlier Italian made wahs seem to have been swapped out at random...likely due to what was available at the time.
Because...what I do believe to be the case here...is that each of these followed essentially the same form factor. Halos, film/trash cans, clover leafs...they're all pot core inductors, 18mm in diameter X 11mm tall.
Granted...I don't know. I've heard that the halos were generally english-made. I suspect that the clover leafs were made on the same factory floor as the rest of the pedal due to the way their coil wires are directly soldered to the posts on the circuit board. Those wires are *very* delicate, making transportation of a completed inductor difficult. That's conjecture, though. I don't know.
So, they were probably sourcing the base models from different suppliers. But where were the ferrites they sources from? Damned if I know. How often were those suppliers swapping out the ferrite suppliers when one wasn't available? Again, damned if I know...but from studying photos of halos, the slightly different markings on the ferrites make it clear that even the halos used several different suppliers in making those inductors.
I'd love to study more examples, but I kinda scored on this one because I don't believe the seller quite knew what they had here. With these early examples commanding prices between 500-1500 a pop, finding additional examples is going to be cost-prohibitive. At least until I get my LLC set up and can write-off the expenses incurred.
Anywho: photos!
This has been dubbed the "clover leaf" inductor by the vintage pedal crowd. Not much information out there on them, and certainly not quite as desirable as the better-known "halo" or "trash can" inductors.
That said...judging by all the different Italian wah circuit boards I've seen over the years, I have to ask the question:
I'm beginning to suspect that there *may* not be all that much difference between the halo, the clover leaf, the film can. Or, rather, is there is enough variance between individual examples to make the categorization less meaningful than one might initially suspect.
Why do I suspect that? Because all the other parts on the various Jen and earlier Italian made wahs seem to have been swapped out at random...likely due to what was available at the time.
Because...what I do believe to be the case here...is that each of these followed essentially the same form factor. Halos, film/trash cans, clover leafs...they're all pot core inductors, 18mm in diameter X 11mm tall.
Granted...I don't know. I've heard that the halos were generally english-made. I suspect that the clover leafs were made on the same factory floor as the rest of the pedal due to the way their coil wires are directly soldered to the posts on the circuit board. Those wires are *very* delicate, making transportation of a completed inductor difficult. That's conjecture, though. I don't know.
So, they were probably sourcing the base models from different suppliers. But where were the ferrites they sources from? Damned if I know. How often were those suppliers swapping out the ferrite suppliers when one wasn't available? Again, damned if I know...but from studying photos of halos, the slightly different markings on the ferrites make it clear that even the halos used several different suppliers in making those inductors.
I'd love to study more examples, but I kinda scored on this one because I don't believe the seller quite knew what they had here. With these early examples commanding prices between 500-1500 a pop, finding additional examples is going to be cost-prohibitive. At least until I get my LLC set up and can write-off the expenses incurred.
Anywho: photos!
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Chuck D. Bones
Circuit Wizard
I'm not gonna claim that I read all of the post in this thread, so please forgive me if I cover some old ground.
The principle factors in inductor performance are:
The stray capacitance causes self-resonance, i.e. the freq at which the inductance resonates with the stray capacitance. It can occur at more than one freq because there is more than one stray capacitance path. Core loss affects the self resonance because core loss increases with freq and can dampen the self-resonance peak.
Self-resonance & core loss are the main reasons that the measured inductance varies with freq.
From an anlysis point of view, it makes more sense to measure an inductor's complex impedance at various frequencies. From that, we can extract the inductance, resistances & capacitance. Because core loss is relatively small and varies with freq, it's most important to assess the core loss at or near the self-resonant peak.
High permeability cores, such as ferrite, have to be gapped in order to prevent saturation, reduce core loss and control inductance. The gap is literally a gap in the magnetic path. Pot cores and cup cores have either an air gap at the center post or better, a non-magnet spacer. The gap is usually a fraction of a millimeter. If we overtighten the screw that passes thru the center of the core, we risk cracking the core. Ferrite is extremely brittle. E-I cores have gaps between the ends of the E and the I on each lamination layer.
MPP (Molypermalloy Powder) cores are made up of a mixture of a magnetic powder and an epoxy binder. This composite material is "self gapped" because there is space between the magnetic particles. One can build very stable and high-Q inductors with MPP. The catch is that MPP cores are only available as toroids (donuts). Toroidal cores are more difficult to wind because each turn of the winding passed thru the center of the toroid. There are machines that can do this, but they are expensive. I have hand-wound many toroids, including one in a CryBaby that my brother has. That Fasel in post #125 is a toroid. It can be repaired by unwinding one or two turns to get a little length on the end of the winding.
The principle factors in inductor performance are:
- Inductance - inductance can vary with flux density
- Copper loss - aka DC resistance. At very high freq (above audio) we also have to include the "skin effect" where current mostly flows on the surface of the wire. Copper loss can be modeled as a resistance in series with the inductance.
- Core loss - this is a complex function of frequency & flux density. It depends on core material and geometry. Core loss can be modeled as a resistance in parallel with the inductance. The effective resistance can be 100K or more.
- Stray capacitance is from turn to turn, and depending on how the winding is arranged, it is also layer-to-layer and start-to-finish. There is also capacitance between the winding and core. The stray capacitance can be modeled as a capacitance in parallel with everything.
The stray capacitance causes self-resonance, i.e. the freq at which the inductance resonates with the stray capacitance. It can occur at more than one freq because there is more than one stray capacitance path. Core loss affects the self resonance because core loss increases with freq and can dampen the self-resonance peak.
Self-resonance & core loss are the main reasons that the measured inductance varies with freq.
From an anlysis point of view, it makes more sense to measure an inductor's complex impedance at various frequencies. From that, we can extract the inductance, resistances & capacitance. Because core loss is relatively small and varies with freq, it's most important to assess the core loss at or near the self-resonant peak.
High permeability cores, such as ferrite, have to be gapped in order to prevent saturation, reduce core loss and control inductance. The gap is literally a gap in the magnetic path. Pot cores and cup cores have either an air gap at the center post or better, a non-magnet spacer. The gap is usually a fraction of a millimeter. If we overtighten the screw that passes thru the center of the core, we risk cracking the core. Ferrite is extremely brittle. E-I cores have gaps between the ends of the E and the I on each lamination layer.
MPP (Molypermalloy Powder) cores are made up of a mixture of a magnetic powder and an epoxy binder. This composite material is "self gapped" because there is space between the magnetic particles. One can build very stable and high-Q inductors with MPP. The catch is that MPP cores are only available as toroids (donuts). Toroidal cores are more difficult to wind because each turn of the winding passed thru the center of the toroid. There are machines that can do this, but they are expensive. I have hand-wound many toroids, including one in a CryBaby that my brother has. That Fasel in post #125 is a toroid. It can be repaired by unwinding one or two turns to get a little length on the end of the winding.
Stickman393
Well-known member
Ladies and gentlemen; this is what somebody who knows what they're talking about looks like. I am but a cave stick man banging sticks together and cursing at the gods as to why I haven't made fire yet.
I had gathered some of what you stated in the post: particularly the bit about stray capacitance and copper loss: though admittedly my words were more along the lines of "bruh it like, electrical fields itself" and "the wire is like lots of coffee straws".
Resonance is something that I struggle with a little. I take it this means when a signal is in phase, seeing as how inductance makes current lag behind voltage.
I'm gathering...that since both phase and frequency are time-dependent, that self-resonance occurs when the frequency of the signal and the phase lag recombine into a signal appears to be in-phase?
Hmm. I do have the ability to measure impedance.
Hmmmm.
...I think I might need to go through all these again and start measuring impedance...
Well, shit. For SCIENCE!
I had gathered some of what you stated in the post: particularly the bit about stray capacitance and copper loss: though admittedly my words were more along the lines of "bruh it like, electrical fields itself" and "the wire is like lots of coffee straws".
Resonance is something that I struggle with a little. I take it this means when a signal is in phase, seeing as how inductance makes current lag behind voltage.
I'm gathering...that since both phase and frequency are time-dependent, that self-resonance occurs when the frequency of the signal and the phase lag recombine into a signal appears to be in-phase?
Hmm. I do have the ability to measure impedance.
Hmmmm.
...I think I might need to go through all these again and start measuring impedance...
Well, shit. For SCIENCE!
Chuck D. Bones
Circuit Wizard
All you need to make a resonant circuit is an inductor and a capacitor. At resonance, the voltage and current are in phase. If we can observe the phase difference, on a scope for instance, we can very precisely detect the resonant frequency. The phase angle is zero because the phase shift in the inductor and the phase shift in the capacitor exactly cancel each other out at resonance. That's kind of the definition of resonance. Works for either series or parallel resonance.
Most of the time when we talk about impedance, we are only talking about the magnitude of the impedance and not the phase difference between voltage & current. With a perfect inductor, voltage leads current by 90°. With a perfect capacitor, current leads voltage by 90°. If we introduce resistance into the inductor or capacitor, then the phase difference is not 90° and will be frequency dependent. So if we want to think about impedance in it's complete form, we have to think about the magnitude and phase of the voltage-current relationship. There are two ways to describe impedance that takes account of magnitude and phase. The same way that we can describe a right triangle by measuring the length of the hypotenuse (the long, slanty side) and the angle between the base and the hypotenuse, we can also describe a right triangle by measuring the length of the base (horizontal side) and the length of the height (vertical side). Either way, we can completely describe the dimensions of the same right triangle. We can use that triangle as an analogy for impedance. The hypotenuse represents the magnitude of the impedance (Ohms), and the angle represents the phase (degrees or radians*). The other way of representing impedance, and the way that electrical engineers do it, is to use the base and the height. The base represents the resistive portion of the impedance. The height represent the reactive component. Think of it this way, the phase difference between voltage and current in a resistor is zero. That means the angle of the triangle is zero, therefore the height of the triangle is zero and the base is the same length as the hypotenuse. Now think about an inductor. The voltage leads the current by 90°. The equivalent triangle would have an angle of 90°, which means that the base is zero length and the height is equal to the hypotenuse. Put a resistor in series with the inductor and now the angle is somewhere between 0 and 90°. The angle depends on resistance, inductance and frequency. Same logic applies to a capacitor.
Here's a picture of what I just said. We use R to represent resistance, X to represent reactance, Z to represent the magnitude of the impedance, and α to represent the phase angle of the impedance.
* radians is a different way of measuring angle. From a mathematical point of view, radians is the natural way of describing angle. Degrees is an arbitrary measure, dividing a circle up into 360 pieces. Extra credit for anyone who knows why it's 360 and not some other number.
Most of the time when we talk about impedance, we are only talking about the magnitude of the impedance and not the phase difference between voltage & current. With a perfect inductor, voltage leads current by 90°. With a perfect capacitor, current leads voltage by 90°. If we introduce resistance into the inductor or capacitor, then the phase difference is not 90° and will be frequency dependent. So if we want to think about impedance in it's complete form, we have to think about the magnitude and phase of the voltage-current relationship. There are two ways to describe impedance that takes account of magnitude and phase. The same way that we can describe a right triangle by measuring the length of the hypotenuse (the long, slanty side) and the angle between the base and the hypotenuse, we can also describe a right triangle by measuring the length of the base (horizontal side) and the length of the height (vertical side). Either way, we can completely describe the dimensions of the same right triangle. We can use that triangle as an analogy for impedance. The hypotenuse represents the magnitude of the impedance (Ohms), and the angle represents the phase (degrees or radians*). The other way of representing impedance, and the way that electrical engineers do it, is to use the base and the height. The base represents the resistive portion of the impedance. The height represent the reactive component. Think of it this way, the phase difference between voltage and current in a resistor is zero. That means the angle of the triangle is zero, therefore the height of the triangle is zero and the base is the same length as the hypotenuse. Now think about an inductor. The voltage leads the current by 90°. The equivalent triangle would have an angle of 90°, which means that the base is zero length and the height is equal to the hypotenuse. Put a resistor in series with the inductor and now the angle is somewhere between 0 and 90°. The angle depends on resistance, inductance and frequency. Same logic applies to a capacitor.
Here's a picture of what I just said. We use R to represent resistance, X to represent reactance, Z to represent the magnitude of the impedance, and α to represent the phase angle of the impedance.
* radians is a different way of measuring angle. From a mathematical point of view, radians is the natural way of describing angle. Degrees is an arbitrary measure, dividing a circle up into 360 pieces. Extra credit for anyone who knows why it's 360 and not some other number.
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Stickman393
Well-known member
Ohhh! I know the answer!
The ancient Babalonyian stickmen counted numbers by having sex. This made getting change for a fiver very inconvenient and awkward, as the shopkeeper had to find somebody nearby to get it on with in order to participate in the legal currency system.
Everybody loved this at first, of course, but eventually everybody just kinda got really tired of all the fucking. Thus why ancient civilizations were absolutely dead-set on the barter system that we still use to this day.
How'd I do? And to think, I used to sit in the back of class with my headphones on.
Feral Feline
Well-known member
Great thread.
Soulid infor, huemour, edjamakationall...
Soulid infor, huemour, edjamakationall...
Chuck D. Bones
Circuit Wizard
I think your talents may not be fully appreciated here. Have you checked out the More Jokes thread in the Open Discussion forum?
This was directed at Stickman, but I think it applies to Feral as well.
This was directed at Stickman, but I think it applies to Feral as well.
Feral Feline
Well-known member
Stickman has many hidden talents.
Not sure how, I mean, he's so thin, where is there to hide any? Yet, he we are.
PS: Those numeralis babyliciousohno-ions... were all bass-60 sexagesimal playahs...
60x60x60x60x60x60
Yeah, I looked it up. Maths is hard for lil ol me.
Not sure how, I mean, he's so thin, where is there to hide any? Yet, he we are.
PS: Those numeralis babyliciousohno-ions... were all bass-60 sexagesimal playahs...
60x60x60x60x60x60
Yeah, I looked it up. Maths is hard for lil ol me.
Stickman393
Well-known member
60 is too thin for bass.
Stickman393
Well-known member
Ok, I'm starting my new sheet with impedance and phase angle measurements.
Not much there yet. Did the two that I had immediately in reach. I'm gonna have to do a little digging to figure out how to make graphs that make sense.
For the future...I just snagged a boomerang *and* a colorsound inductor wah. What what. That boomerang will be attempt #2 at getting an El rad on the document.
Not much there yet. Did the two that I had immediately in reach. I'm gonna have to do a little digging to figure out how to make graphs that make sense.
For the future...I just snagged a boomerang *and* a colorsound inductor wah. What what. That boomerang will be attempt #2 at getting an El rad on the document.
Stickman393
Well-known member
Its an advantage of being entirely two-dimensional.
One can present a facadé of knowledgeable-ness whilst remaining less deep than a puddle.
Honestly, I take pride in inhabiting "the peak of mount stupid" on the dunning-kruger curve in as many different disciplines and I can muster.
Did you know, for example, that quantum physics states that for every disorganized drawer of cables and wires, another just like it exists elsewhere in the universe? What's more, if you change the position of those cables or wires, the other changes with it! ItS sCiEnCe!
I am also a firm adherent to the belief that jokes get funnier when you have to explain them. But nobody recognizes my genius...
Uhhh...what was I saying? Oh yeah. Deep. Still waters run deep.
So deep. So so deep.
*Stares hypnotically into his stick belly-button*
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Feral Feline
Well-known member
Well, that was deep... Well deep.
UtilityBeltFX
Well-known member
Thoughts on Tom Morello's original Crybaby? He refers to it as "early 80s," but it appears to have a DC jack input. Could be a mod? In the years since he's been photographed with a "Crybaby Classic" and of course his new signature wah, but I've always been curious about the OG. Which inductors might have been in there?
Chuck D. Bones
Circuit Wizard
Careful, there might be a farting dragon down there.
Stickman393
Well-known member
Looks like a hot potz II, which puts it in the early 90s. Most likely a 1408P. Looks like a stock barrel connector to me...though it's possible that it's a modification.
That was a good era for crybaby inductors. Anything late 80s-mid 90s, really. In the late 80s they used a Magnetics type F 1811p. 90s...dunno the exact grade, but I know that they used an N30 1408p on some when they started making pedals for budda. I'd venture a guess that they used N48 for a while.
I see two possibilities: either it's an older 1811P variant from the late 1980s that was modified with a barrel plug instead of a 3.5mm input and a new pot, or it's a stock model from 1992 onwards. Can't remember if he used much wah on their self titled in 92, but I know it's all over evil empire.
His signature model is a GCB-95 with a paint job, unfortunately. Typically a stock toroid inductor: honestly, I'm not super impressed with dunlops toroids...but they're a fair sight better than the blue and black cans they used in the mid 80s.
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