Tonerider pickups..

[zeromick]

I'm lead to believe the Tonerider Octane is pretty good... hehe

[dave.king1]

Toneriders & Squier CV pickups come out of the same loading dock according to them in the know.

Not all Squier pickups are created equal, the CV ones in the CV Thinline are marked TCA1N & TCAN1B

[Simon Barden]

N for neck and B for bridge. Fairly standard.

[corsair]

Here we are, lads....

Tonerider ACII with a series/coil split/parallel switch where the tone pot used to be and the tone pot shifted to the old output socket spot.



The new headstock design....



... and as she is now,



I've sanded the back of the neck right down to 2000 grit and oiled it very, very lightly with Lizardspit, and it is beyond delightful to play!!

The pickup is just a monster; the impedance readings were switch up (series) - 2.2kΩ, middle - (coil split <north>) - 4.21kΩ and down (parallel) - 8.25kΩ but don't let that fool you; there is very little volume loss between settings!! Would someone please explain that to me, because I don't know why that should be so!!
The tonal differences are quite marked or quite subtle, depending on what outboard stuff I have dialled in, but at no FX with the tone approximately in the middle, the difference is subtle and if I had to quantify them I'd say that parallel is balls out, full on h/b noise - will do Peter Green or Slash with aplomb; coil split is a touch "thinner" as you'd expect and series is like parallel but with more pronounced hi-end happening.

I do know that I like it - a lot and will upgrade my first PBG kit with Toneriders of some stripe; just epic bang for the buck!!

[Simon Barden]

Simply sounds like your switch settings are actually the other way round to that you've described. The parallel setting will have the lowest resistance, the single coil the middle resistance and the series connection the highest resistance. So simply replace 'series' with 'parallel' and 'parallel with series' and it all makes sense.

I was recently setting up someone else's ES-1 build and they had the Tonerider AC4 pickups in. They sounded OK but were very hot, too hot really for the guitar and I had to turn the volume way down to get a clean tone without the front end of the amp being pushed. The ACIIs would have been a better fit.

[corsair]

Ah, there we go; thanks for that Simon - I had indeed transposed the series/parallel in describing the switch!!

However, my question remains; why, when there is such an enormous discrepancy in impedance values, does the volume not alter appreciably when switching between positions??

[dave.king1]

Pretty simple maths really

To use easy numbers 4 + 4 = 8 ( series ) 4 And 4 in parallel = 4/2 = 2.

The current & voltage remain constant in a parallel & series circuits at the common point ( jack socket in this case ) P= I x E

[Simon Barden]

The impedance value of a pickup is only really useful in estimating it's output relative to another pickup of the same configuration. If you swap a humbucker from the normal series arrangement to a parallel arrangement, then each individual coil is still creating the same signal. The difference is that in a series configuration, the signal from one coil is then passing through the second coil, so the output from the second coil is superimposed on top of that of the first coil. For a parallel configuration, the two voltages are simply averaged to get the resultant output. (There is also some extra interaction between the two coils but it's pretty complicated stuff and beyond my knowledge, but it does contribute slightly to the sound).

So for a series connection, this means that if the output from the first coil at a certain moment in time peaks at say +1v, then the output from the second coil will be added to this, so that if the second coil also generated a signal that peaked at +1v, then the total output at that point would be +2v. If one coil generated +1v and the other +0.5v at a point in time, then the combined output would be 1v + 0.5v = +1.5v.

For a parallel connection in the same circumstance, the voltage outputs of each coil would be averaged, so that if both coils generated a peak of +1v, the averaged value would be (1v + 1v)/2 = +1v. If one coil generated +1v and the other +0.5v at a point in time, then the combined output would be (1v + 0.5v)/2 = +0.75v. So in a very simple model, the output of a series-wired humbucker should always be double that of a parallel-wired humbucker.

This is one reason why parallel wired humbuckers produce a lower output than those wired in series. (Dave, I think you were thinking about passive components in series and parallel arrangements, but pickups are voltage/current generators so are a special case).

But the two coils don't produce the same waveforms. They are located around 17mm/0.67" apart and so each see a different part of the string. Whilst for the fundamental note and the first couple of harmonics, the string should be going in the same direction (although at different levels of deviation from the at-rest position). However, when you get to the much higher harmonics, the string might be moving in one direction above one coil, but in the opposite direction above the other coil. In this instance, you get either partial or total cancellation of the signals, so that a lot of the higher harmonics are either very attenuated or eliminated entirely. This is one reason why single coils sound brighter than humbuckers - they simply have a lot more higher harmonics present.

Another reason is that each pickup has inductance, impedance and capacitance values that help define the way the pickup sounds.

Here's an equivalent electrical representation of a pickup:



Vs is the AC source voltage generated by the pickup. Vo is the final output voltage. The inductance L and the coil impedance R, are in series with the voltage generator, whilst the capacitance is in parallel with the other components.

This arrangement forms a 2nd order low-pass filter with a resonant peak at the 'turnover' frequency point. At frequencies above this point, the frequency response drops off quite quickly at a rate of -12dB per octave.

Series-connected humbuckers generally have higher resistance, inductance and capacitance than a normal single coil pickup, which results in a lower resonant frequency than on a single coil pickup. E.g. for a low-output single coil pickup with a 5k ohm resistance, an inductance of 2 Henries and a capacitance of 100pF, the resonant peak is at 9.2kHz, with an amplitude boost of +27dB at the peak. For a high output humbucker with a 15k ohm resistance, an inductance of 10 Henries and a capacitance of 200pF, the resonant peak is at 3.6kHz, with an amplitude boost of +23dB at the peak.

Here are those values for a single coil and a humbucker plotted on a graph. This makes it easy to see the lower resonant peak frequency value of the humbucker compared to the single coil.



Lower coil resistance and inductance values of less powerful humbuckers (such as PAF style ones) increase the resonance peak frequency - which explains why these lower powered humbuckers can sound very clear in comparison to the hotter wound ones.

Note that adding volume and tone controls also affect the resonance peak, but at least this shows the other main reason that humbuckers sound darker and more middley than single coils - because the upper-mids and lower trebles are boosted (compared to the flat response of a single coil at these frequencies), whilst the mid- and upper-treble frequencies are filtered off. A single coil has a higher resonance peak - so has a flat response in the middle frequencies - whilst it is the treble frequencies that are boosted and that the low pass filtering doesn't start to cut frequencies out below the upper threshold of (good) human hearing at 20kHz.

Of course, the guitar's sound is then generally passed through a guitar amp with a speaker that doesn't put out much above 5-6kHz, so that's another low-pass filter the guitar's sound passes through. So you'd rarely get to hear the resonant peak of a single coil pickup, but you do get to hear some of the mid-biased peak of a humbucker.

Getting back to series/parallel humbucker operation, when the two coils are wired in parallel, then each coil behaves as if it's a single coil, so the inductance, resistance and capacitance values of the series-wired humbucker are to all practical purposes halved, and the resonant peak of each coil of the humbucker is moved upwards, giving a much less middley, far more trebley sound. Which is why a humbucker in parallel mode sounds pretty close to a single coil - it's only the phase cancellations and reinforcements at different frequencies caused by the two coils sensing different locations along the string that create a difference in sound to a true single coil. But the benefit is that as one coil is reverse polarity and reverse wound to the other one, that any airborne mains noise is picked up as an out-of-phase signal on one coil compared to the other one, cancel out when the two coil signals are combined and so it remains humbucking and (almost) noise free.

So to summate:


*In series mode, one coil's output is added to the second coil's output; whilst in parallel mode, the two coil outputs are averaged. A series-wired humbucker produces a stronger voltage signal (by roughly 6dB) than the same pickup wired in a parallel configuration.

*Each coil in a standard side-by-side humbucker produces a different output waveform because it is sensing a different part of the string. The higher harmonic frequencies interact and cause a frequency-dependent mixture of signal addition and cancellation. This is one reason why humbuckers sound different to single coils.

*A pickup, whilst creating an AC voltage when the strings vibrate over it, also acts as a 2nd order low pass filter with a resonant peak, above which the output falls off a- 12dB/octave.

*The resonant peak of a humbucker wired in series mode is at a significantly lower value than that of it wired in parallel mode. This lower peak frequency boosts upper-middle frequencies whilst frequencies much above this frequency are filtered out.

*In parallel mode, each coil has a frequency response more like a single coil, with a much higher resonant peak frequency, which leaves the mid frequencies flat and boosts the treble frequencies. The low-pass filter effect only reduces frequencies at the very upper reaches of human hearing and above, so the sound is a lot brighter than that of the pickup in series-wired mode.

*If wired correctly, a parallel-wired humbucker retains its humbucking noise-cancelling attributes.

Hopefully I've explained in a general sense how the series and parallel modes on a humbucker give different sounds and different output levels. I knew some of this before, but I had to look a good bit up today, so I'm by no means an expert on this subject!

[corsair]

This is fabulous; thanks ever so much, Simon!

I've always found understanding pickup theory a little like a black art but this I can understand.... I will have to re-visit it a few times to nail it home, though!!

Thanks, too, Dave!

[Hobastard]

Here we are, lads....

Tonerider ACII with a series/coil split/parallel switch where the tone pot used to be and the tone pot shifted to the old output socket spot.



The new headstock design....



... and as she is now,




!!

That looks pretty sweet to me..... (an Ex Navy Aircraft Maintainer).....