Silent single coil

[Possum]

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There's more than just just string sensing area that defines difference between single coil and humbucker. I make a single coil that senses the strings in almost the same area as a bucker does and they don't sound the same. The reason is a humbucker if they are using equally wound coils don't just cancel 60 cycle hum, they cancel alot of other frequences in "notches" along the audio spectrum. I'm doing some experimenting now with equal wound coils and variations of mismatch. The thing I don't like about equally wound coils is that when you turn the volume pot down the pickup sounds really flat sounding. With a certain amount of offset this problem goes away. Question is how MUCH offset, where is the sweet spot? On a neck bucker a certain mismatch can actually make the pickup muddier than equal wound coils.

[Mike Sulzer]

There's more than just just string sensing area that defines difference between single coil and humbucker. I make a single coil that senses the strings in almost the same area as a bucker does and they don't sound the same. The reason is a humbucker if they are using equally wound coils don't just cancel 60 cycle hum, they cancel alot of other frequences in "notches" along the audio spectrum. I'm doing some experimenting now with equal wound coils and variations of mismatch. The thing I don't like about equally wound coils is that when you turn the volume pot down the pickup sounds really flat sounding. With a certain amount of offset this problem goes away. Question is how MUCH offset, where is the sweet spot? On a neck bucker a certain mismatch can actually make the pickup muddier than equal wound coils.

A pickup senses the part of the string over the pole piece. The sensitivity falls of rapidy away from the pole piece. Thus, a humbucker senses two areas of the string, one for each pole piece. This leads to the cancellation of certain harmonics where the string motion is opposite over the two pole pieces. This can be thought of a comb notch filter, but remember that the frequencies canceled are different for each string since they are determined by the harmonics of each string.

Humbuckers are also different from single coils because they have lower resonant frequencies and Qs.

A pickup does not sense uniformly over the width of the whole coil as is sometimes stated.

[Possum]

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I don't hear this string cancellation you're talking about, don't forget those two sets of poles aren' very far apart so I doubt the string could be opposite the other poles position. I"ve done prototype humbuckers using unique processes where you could actually hear double notes from both coils at the same time. Now if you're talking a single neck vs. bridge single coil I could buy that theory more easily and that is plainly heard. the cancellation I'm talking about is from both coils being wound the same number of turns. I am in the process right now of unwinding one of the coils 50 turns at a time and listening and recording the results of it fully being reassembled and installed into a guitar. Taking off only 50 turns you can hear other frequencies starting to open back up for fuller tone. the equal wound coils sounds great and very definied until you roll the volume pot down some, then it sounds flat and lifeless because too many frequencies just aren't there; which is probably why alot of these noiseless single coil ideas are lackluster.

The single coil that I designed that senses the string from 3 places doesn't sound at all like its missing frequencies due to any kind of cancellation and is very fat sounding.

[David Schwab]

I don't hear this string cancellation you're talking about, don't forget those two sets of poles aren' very far apart so I doubt the string could be opposite the other poles position.

Sure you do. Humbuckers have reduced high end partly as a result of the phase cancelation. As you move the two coils farther apart, the notch shifts until you get the 2 and 4 positions on a Strat, for example.

Don't forget that humbuckers have the coils wires up out-of-phase. The only reason they don't sound that way is the reverse magnets. So think of it as the waveform on one coil is going up, the other is going down. And the string is not vibrating the same over each coil because they not sensing the string at one location. Each one hears a slightly different portion of the harmonics on that string. So the higher harmonics "fall in the space" between the two coils, and miss the one side up the other side down effect, and get canceled out.

And then the lows and mids are reinforced when the two waveforms are summed.

The single coil that I designed that senses the string from 3 places doesn't sound at all like its missing frequencies due to any kind of cancellation and is very fat sounding.

The single coil doesn't have another reverse polarity coil hooked up to it. A single coil can't cancel out itself. If it senses the string in two locations, both are in phase with each other.

[Mike Sulzer]

I don't hear this string cancellation you're talking about, don't forget those two sets of poles aren' very far apart so I doubt the string could be opposite the other poles position.

The fundamental component results in the entire strong vibrating in the same direction with the maximum velocity and displacement in the middle.

The 2nd harmonic (or first overtone) has the two halves moving in the opposite directions with a null in the middle.

And so on.

A humbucker senses the string at two spaced points with the same polarity, or phase. (Both electrical and magnetic polarities are reversed.) The spacing between the poles of a humbucker is about 3/4 inch. If the scale is 25.5 inches, and we can get full cancellation with a wavelength of twice the spacing, then with an open string we can get strong cancellation from the 17th harmonic and above.

I can easily measure the 56th harmonic on an open E string (6). So there is plenty of frequency range where partial cancellation can occur. The higher harmonics are mostly picking transients, and so we expect the initial sounds of the string to be different when using a SC or a humbucker.

This degree of cancellation can be affected at the very high frequencies by using different numbers of turns, but you really are not changing things very much.

[Possum]

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Well I agree with David, but its because there are two coils, the cancellation is happening in the coils not from the string. The cancellation is happening because they wired to do that, the more hum you kill the more other frequencies you're killing too. Read the Lemme thing again. How could the string in the space of actually slightly less than 3/4 inch have one section vibrating in one direction and the other going in the opposite direction, that quite a twist there. If that kind of cancellation were happening then a single coil with two wide spaced pole sets would make it sound like a humbucker, well it doesn't. What I'm experiencing in these experiments is that equal wound coils actually sounds brighter because alot of frequencies are chopped out, but the resonant frequency is actually low. Start to mismatch the winds and those frequencies are reintroduced so the pickup starts to sound darker. I've only taken off 50 winds so the rez freq really hasn't changed much. The way you're describing string vibration it sounds like the string is divided up into very tiny little sine wave segments, I don't think its doing that, the waves are much longer than could be split over such a small space on a bucker pole set spacings. I could be wrong but if this effect is there its really insignificant. Somewhere there's a website that shows pickup place effects and how the strings vibrate.

[Mike Sulzer]

Well I agree with David, but its because there are two coils, the cancellation is happening in the coils not from the string. The cancellation is happening because they wired to do that, the more hum you kill the more other frequencies you're killing too. Read the Lemme thing again. How could the string in the space of actually slightly less than 3/4 inch have one section vibrating in one direction and the other going in the opposite direction, that quite a twist there. If that kind of cancellation were happening then a single coil with two wide spaced pole sets would make it sound like a humbucker, well it doesn't.

The string vibrates as I described; view this animation to see the first four modes: The Vibration of a Fixed-Fixed String. Scroll down to find the animation. If you accept that it works that way for the the first four modes, then if you establish that higher harmonics exist by measuring them, then they work in a similar way.

Suppose that you connect the coils of a humbucker in the reverse of the correct way. What do you hear (and I do not mean the hum)? Why?

Humbuckers cancel hum but if the signals are the same in the two coils they add. The coils do not cause cancellation as you are saying. Canceling more hum does not cancel more signal.

[Possum]

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Well maybe there is some string cancellation, it seems a bit far fetched to me. That would mean that every different note on the fretboard would have different amounts of cancellation? Hum cancelling though does not perfectly select extraneous hum and knock that out only. Read the Lemme document, he's done alot of work on this stuff and says that the coils are notching out other frequencies and thats what I believe. Whatever the cause this does happen. I've not listened to a bucker hooked up non-hum cancelling but am guessing it would sound alot fatter because frequencies aren't being notched out of the signal.

[Mike Sulzer]

That would mean that every different note on the fretboard would have different amounts of cancellation?

In terms of harmonics, yes, that is exacty right. But in terms of frequency, the response is the same for all fretted locations on a string, but different for each string. In effect, each string has its own filter that controls the response. That is why a string has a consistent sound: the frequency response of each fretted note is the same.

Read the Lemme document, he's done alot of work on this stuff and says that the coils are notching out other frequencies and thats what I believe.

Read it yourself.

Lemme: "Humbucking pickups have certain notches at high frequencies, because the vibrations of the strings are picked up at two points simultaneously."

He is saying exactly what I am saying.

[Possum]

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I just bit my tongue off, ouch....

[Possum]

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There is still something not accounted for here though. Why do single coil stacked noiseless pickups sound as flat and lifeless with equal coils as a regular humbucker? Its only sensing the string at one point. I still think there is some kind of cancellation happening in the coils themselves. Unmatching regular humbucker coils is a solution and not always predictable results.

[David Schwab]

Stacked pickups have a lot of low end phase cancelation. They come out very bright and thin sounding. So typically they are over wound to bring up the low end, and that of course changes the high end.

The newer stacks like the Dimarzio virtual vintage sound a lot like single coils.

On this track, the guitar parts are played on a Strat style guitar with Gibson scale length (a bit less chimey) and I used a virtual vintage solo pro (a bridge pickup) at the neck. This was a guitar a built for someone, and that's the way they wanted the pickup.

Bass Head

So you can hear that they sound just like real single coils.

(the guitar in the recording)

[soundmasterg]

The Gretsch Filtertrons are very evenly wound between the two coils, according to TVJones. Perhaps this is one reason why they are brighter than many humbuckers, aside from the narrower coil sensing area and lower winds?

Greg

[Possum]

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Now, this becoming contradicting. Why would there be low end phase cancellation in a stacked single coil if its only sensing the strings from one point? This is why I think there is something else going on with equally wound coils.

Hard to say anything about TV Jones or old Filtertrons, I'd have to examine the real alloys and everything about them to figure them out. His pickups are oustanding.

[Mike Sulzer]

There is still something not accounted for here though. Why do single coil stacked noiseless pickups sound as flat and lifeless with equal coils as a regular humbucker? Its only sensing the string at one point. I still think there is some kind of cancellation happening in the coils themselves. Unmatching regular humbucker coils is a solution and not always predictable results.

Traditional stacked humbuckers have lower resonant frequencies and Qs than SCs. They simply do not have the high frequencies.

There are two major differences between SCs and humbuckers:

1. Removal of high frequencies due to the circuit components, that is, more L from two coils causing a loss of highs.

2. Removal of selected highs in a periodic comb filter due to the spacing of the two sampling points on the string.

Suppose you buffer a standard humbucker in the guitar. The resonant frequency rises because you have removed the effect of the capacitance of the cable. You have removed the first effect, and if you want, you can use a selected C to put the resonance where it would be with a single coil. But the second effect remains.