"Tracking" speed of pickups?

[Plectrum]

Just something I've noticed:

More and more people are talking about "Tracking" and the "speed" that a pickup reacts "to your picking" etc.
Now, AFAIK, due to the laws of physics, the electromagnetic forces involved in induction of this kind are operating at something approaching light speed.

That sounds slow sometimes?

I have played some sludgy sounding and brazenly bright pickups in my time, and have never felt that they are reacting "slowly". Ever.

Is it possible some are hearing something I've not ever experienced, am I mistaken about the physics involved, or are they just describing something else completely erroneously?

(BTW: I am aware of the hex/midi devices and I'm not talking about that stuff).

[CRU JONES]

Just something I've noticed:

More and more people are talking about "Tracking" and the "speed" that a pickup reacts "to your picking" etc.
Now, AFAIK, due to the laws of physics, the electromagnetic forces involved in induction of this kind are operating at something approaching light speed.

That sounds slow sometimes?

I have played some sludgy sounding and brazenly bright pickups in my time, and have never felt that they are reacting "slowly". Ever.

Is it possible some are hearing something I've not ever experienced, am I mistaken about the physics involved, or are they just describing something else completely erroneously?

(BTW: I am aware of the hex/midi devices and I'm not talking about that stuff).

This is a very interesting perception of pickups by guitarists. I really very much on these perceptions that guitarists make. I have come to find that guitarists that play a lot and gig a lot don't miss much To what they actually mean, is where you come's in as interpreter!

There are some speed issue's that do exist with electromagnetic pickups. A current is not induced in a pickup at the speed of light. A normal pickup has reactance and an imperfect phase response. Speeding up a pickup as fast as possible may not get you the perception of a "fast tracking" pickup... But then, one never knows until they try!

Cheers,
Ethan

[Plectrum]

This is a very interesting perception of pickups by guitarists. I really very much on these perceptions that guitarists make. I have come to find that guitarists that play a lot and gig a lot don't miss much To what they actually mean, is where you come's in as interpreter!

There are some speed issue's that do exist with electromagnetic pickups. A current is not induced in a pickup at the speed of light. A normal pickup has reactance and an imperfect phase response. Speeding up a pickup as fast as possible may not get you the perception of a "fast tracking" pickup... But then, one never knows until they try!

Cheers,
Ethan

Sure, it is somewhat slower than the speed of light from what I have been taught. It is however ridiculously fast esp. when compared to sound.
299,792,458 m/s : 340 m/s
At just 1% C, we'd be talking 3 million m/s.
If we mic an acoustic at one foot distance, then put on our cans and record without hearing a delay (and with the right gear and chain, most professionals don't complain)... How can we possibly hear the sort of delays that E/M induction would cause?

Surely, reactance is a resistance; an attenuation, not a delay?
AFAIK also, phase response may delay the duty-cycle of waveforms, but not the amplitude of a combination of waveforms - like the attack of a note etc. So the perceived attack should be in the exact same place, even if the duty cycles are delayed.

I'm not trying to shoot you down here, just trying to work it all out. This stuff fascinates me.

[Chuck H]

It's true enough that if an inductor is reacting there is a time constant in how fast it can do that. This would be relative to the current, which is almost none since the pickup is playing into an impedance about 30 to 60 times greater than it's own, and the power supply, which in this case is the magnet, acts as a somewhat constant current I suppose. BUT... The guitar cable can have considerable capacitance. This would certainly present a low impedance to the pickup output in the HF. But since the magnet is a constant current I do wonder if the reaction time of the coil to is notable. I'm not really sure but it seems plausible.

[Mike Sulzer]

That inductance and capacitance are a low Q resonant circuit. If you input a transient to a resonant there is a build up of the response over time. You could think of this as a sort of delay if you like. There is no other significant delay in a pickup, and this one is chacterized by the frequency response of hte pickup. When playing with the volume all the way up, that resonance is a very important contributor to the tone of the pickup.

It's true enough that if an inductor is reacting there is a time constant in how fast it can do that. This would be relative to the current, which is almost none since the pickup is playing into an impedance about 30 to 60 times greater than it's own, and the power supply, which in this case is the magnet, acts as a somewhat constant current I suppose. BUT... The guitar cable can have considerable capacitance. This would certainly present a low impedance to the pickup output in the HF. But since the magnet is a constant current I do wonder if the reaction time of the coil to is notable. I'm not really sure but it seems plausible.

[Joe Gwinn]

Eddy currents can slow the response time. The classic way to build a slow-reacting (time-delay) DC-powered relay is to put a thick copper sleeve around the core, and wind on top of the sleeve.

[David Schwab]

I'd bet these guitarists are feeling the response of a tube amp, and not the pickups. I've been playing for over 40 years, and I never once felt a slow pickup. But I have felt slow responses from tube amps.

Solid state amps always feel quicker.

[copperheadroads]

Ceramic magnet pickup (less alloy)
Solid state amps
Ash body guitar (compared to alder of mahogany)
All have a quicker attack ...Lol

[Steve Conner]

It sounds like buzzword mania and magical thinking to me. Your average guitarist has no idea how the electric part of his instrument actually works. He thinks he does, but all he actually knows is a bunch of folklore and superstition.

So no, pickups don't have a time delay in reacting to your playing. They have a resonance as Mike said, but it is hard to understand how that could sound like a delay.

The human brain is such a fickle thing, though. If you don't believe that a pickup can sound slow, maybe you just won't hear slow.

The other thing that bothers me is hi-fi reviewers who say that a woofer sounds "fast". If it really was fast, it wouldn't need a tweeter.

[Mike Sulzer]

Eddy currents can slow the response time. The classic way to build a slow-reacting (time-delay) DC-powered relay is to put a thick copper sleeve around the core, and wind on top of the sleeve.

1. Eddy currents lower the Q of the resonance. That decreases its response time, kind of the reverse of a delay.

2. Eddy currents put a small dip in the midange response, as seen in many humbuckers. That could be thought of as a delay over a part of the freqency range.

[Mike Sulzer]

The other thing that bothers me is hi-fi reviewers who say that a woofer sounds "fast". If it really was fast, it wouldn't need a tweeter.

Yep. I think a woofer sounds "fast" when its level is adjusted properly with respect to the midrange and tweeter, assuming the woofer response is flat enough so that the balancing is worth doing.

[FunkyKikuchiyo]

I think players are hearing the envelope of the note which can be affected by many things, but quite often by magnet orientation. The dynamics of a pickup change based on design, and strings do not vibrate in the same manner in every vector, so which way the magnets are pointing will change things. Strats have more "pop" and sound "faster", and incidentally the magnets are perpendicular to the fingerboard, so a lot of that clank in the instrument comes through in comparison to another instrument. It is a similar phenomenon to comparing rest stroke and free stroke on a classical guitar. Each one interacts with the bridge and top of the instrument in different ways.

To my ears, pickups with a broader dynamic range sound "faster", so it might be worth checking cited examples to hear if the ones being called "fast" are also more dynamic. Very crudely and broadly speaking, I've found instruments with lower gauss and/or higher eddy current loading to be less dynamic.

Envelope (attack, sustain, decay, release) is one of those audible things that I haven't seen measured in any particular way as of yet, so it can be pretty tricky. As David S. said, amps can affect this quite a bit too, and when you consider the interaction elements between a pickup and the first gain stage of an amp, then it gets even more convoluted.

[David Schwab]

The other thing that bothers me is hi-fi reviewers who say that a woofer sounds "fast". If it really was fast, it wouldn't need a tweeter.

That's mixing time with frequency. Woofers aren't made to produce high frequencies as well, and most have an upper frequency cutoff, although a full range speaker does a fairly good job.

I can say as a bass player that smaller speakers feel faster, and since they are mechanical that makes sense. Large speakers have more inertia to over come. That's why tweeters are small and light. But of course smaller speakers don't reproduce the lows the same way as something like an 18" woofer. 10" speakers on the other hand feel punchier. I like 12" speakers for bass, but they have been uncommon until recently.

[FunkyKikuchiyo]

I had another thought - the time thing can be heard with wireless kits. If you stand far enough away from your amp you can "feel" a delay in the sound since the signal travels to the amp fast enough, but the sound takes a bit more time to travel back to you. A lot of guitar players comment on this and find it a bit strange feeling. It is a bit like when the audio is out of synch with video and words don't line up with lips. I wouldn't say I've ever gotten the same effect by changing pickups or amps.

[Joe Gwinn]

1. Eddy currents lower the Q of the resonance. That decreases its response time, kind of the reverse of a delay.

Isn't that backwards? A high-Q resonator takes time to build up, and a long time to ring back down. Q is basically the ratio of circulating energy in the resonator to incoming/outgoing energy.

2. Eddy currents put a small dip in the midrange response, as seen in many humbuckers. That could be thought of as a delay over a part of the frequency range.

How do we know that it's a small dip? Given the sqrt[f] dependence of eddy currents, one would expect increasing effect as the frequency increases. Something else must also be happening.