Pickup as pickup simulator

[Eddododo]

My buddy has a need for a switchable pickup sim for some late-in-chain effects that 'prefer' not to follow buffers. He and I have an appreciation for silly things, so we like the idea of having a pickup visible, top routed into the pedal. For house cleaning I would ground the pole pieces and shield the bejesus out of anything that needs be bejesus'd. I will include a tone and vol pot. It will effectively be an effects loop,  which would enact the early chain buffered pedals.  So aside from those details I literally plan on running the signal through the pickup hot to cold (or vice versa). Am I missing something problematic?

[Digital Larry]

All I was going to mention was the very likely reality of hum, but you seem aware of that already.  And the magnet will probably attract iron filings from the environment, supposing there are any.

[Eddododo]

Yes hopefully accounted for environmental hum- is single coil hum something I have to worry about with the pickup in series like this?
Oddly enough I had not considered the magnet issue, but I may just consider it a non issue

[DavidRavenMoon]

You don't need the magnet. Just the coils. And if you use two coils you will cancel the hum.


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[ashcat_lt]

...if you use two coils you will cancel the hum.

If they're reverse wired, yes.  You'll also get a different amount of inductance (and DCR, which usually isn't the issue) and all of the change in frequency response that entails.  Could be fun to have a Series/Parallel switch - maybe on a P/P like you might put on an actual guitar - to give you even more tonal options.

[graemestrat]

I'm wondering if it is going to work very well if it is late in your chain. Being late in the pedal chain will probably mean that the signal has been compressed somewhat which will make it unlike the pickup signal even with a simulator coil(s).
Just a thought......

[Transmogrifox]

I'm wondering if it is going to work very well if it is late in your chain.

He and I have an appreciation for silly things...

This may point out a different definition of what "works" means.

In the end most pickup simulators don't "work" because they don't "un-do" the pickup from the guitar that's driving them.  So unless you are using a guitar with a special pickup system that is practically "flat" or uncolored, then you're combining the effect of two pickups when you engage a pickup simulator.

This doesn't necessarily sound "bad", but it doesn't sound just like replacing the pickup in your guitar.

I think the same argument holds true for putting a pickup simulator later in the signal chain:  It may not sound "just like" replacing the pickup in your guitar, but it may sound good.  It's definitely worth a try.

I think it would be good to keep the magnet in there.  It provides a constant magnetic field bias and the extra magnetic material will effect the inductance of the coils.  The magnet will maintain any nonlinear effects of the pickup and make sure the inductance is correct.

Just some more crazy musings:
You could house it in an iron box to reduce the amount of hum (magnetic shielding).  This is half-joke because the weight of an iron box is unruly, but it's not entirely out of the question.  It would still be somewhat effective even if you mounted the pickup exposed on top.  Ideally it would be a box about 24"x24"x24" with the pickup suspended in the center.  The inside could be lined with ferrite tiles similar to what is found inside an RF emissions chamber.  The large dimension would be to minimize the amount of influence the magnetic shield would have on the pickup's inductance, although it may be overkill.

Something I did in software (DSP-land) was to simulate a pickup with a first-order high-pass filter followed by a second-order low-pass filter.  The high-pass was to emulate the balance based on pickup position and also to take the "boomy-ness" off of dull humbuckers.

That did the simulation part -- the next part is to "de-simulate" the source pickup.  This is just turning your guitar's pickup frequency response upside-down to undo what has already been done to it.

The point is you might be able to make a "de-simulator" with a pickup.  Basically you put the pickup in a feedback loop so you amplify the inverse of its impedance.  That way you approximately cancel the effect of your source pickup and then apply the effect of the target pickup.  This is a somewhat expensive way to do this, but I suppose it's cheaper than having multiple guitars with different pickups.  If you have money, multiple guitars is the way to go

For example, Kenny Wayne Shepherd had some 12 or 15 stratocasters on the rack backstage.  He used about 3 or 4 different ones that I noticed during the performance.  I assumed the difference between the strats must have been variations on pickups and string weight.  Some may have simply been hot-spares that he could grab when one went out of tune.  I was working as local grunt support for that show so I was backstage doing the setup & tear-down so I got a good look at the rig.  I didn't get a chance to talk to the tech to learn anything specific about the difference between the strats.  Either way, a rack full of guitars would be the way to go if really wanting different pickup sounds.

[Eddododo]

Well to be clear the main goal here is to simulate the loading of a raw guitar as his fuzz is preceded by buffered pedals... basically looking at R.G.'s pickup simulator but doing it with a pickup instead of a little transformer

[ashcat_lt]

Well to be clear the main goal here is to simulate the loading of a raw guitar as his fuzz is preceded by buffered pedals... basically looking at R.G.'s pickup simulator but doing it with a pickup instead of a little transformer

Yep.  It's all about the inductance of the pickup against the low impedance of a fuzz creating an LPF which some people for some reason think is more "authentic" than any other LPF topology in this situation. 

[DavidRavenMoon]

In the end most pickup simulators don't "work" because they don't "un-do" the pickup from the guitar that's driving them.  So unless you are using a guitar with a special pickup system that is practically "flat" or uncolored, then you're combining the effect of two pickups when you engage a pickup simulator.

That's not the point. People use these types of circuits when you have a fuzz that has a low impedance input that ends up loading down the pickup. If you place a buffer before the fuzz, or use active pickups, you won't have that interaction. So placing a coil before the fuzz circuit simulates that interaction because the fuzz is loading the coil and reducing the frequency response.

So it doesn't matter what the original pickup sounds like since the buffer is isolating it from the circuit.



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[amz-fx]

My buddy has a need for a switchable pickup sim for some late-in-chain effects that 'prefer' not to follow buffers. He and I have an appreciation for silly things, so we like the idea of having a pickup visible, top routed into the pedal. For house cleaning I would ground the pole pieces and shield the bejesus out of anything that needs be bejesus'd. I will include a tone and vol pot. It will effectively be an effects loop,  which would enact the early chain buffered pedals.  So aside from those details I literally plan on running the signal through the pickup hot to cold (or vice versa). Am I missing something problematic?

I bought a Tele pickup and mounted it inside a small metal box with in/out jacks. Its purpose is to use when I need to convert the low impedance output of my signal generator to something more resembling a guitar's characteristics.

For best hum rejection, use two wires (signal and gorund) to the input and twist them tightly together. Same for the output. You already mentioned that you would be shielding it too, so that's good.

http://www.muzique.com/lab/pickups.htm

Best regards, Jack

[DavidRavenMoon]

My buddy has a need for a switchable pickup sim for some late-in-chain effects that 'prefer' not to follow buffers. He and I have an appreciation for silly things, so we like the idea of having a pickup visible, top routed into the pedal. For house cleaning I would ground the pole pieces and shield the bejesus out of anything that needs be bejesus'd. I will include a tone and vol pot. It will effectively be an effects loop,  which would enact the early chain buffered pedals.  So aside from those details I literally plan on running the signal through the pickup hot to cold (or vice versa). Am I missing something problematic?

I bought a Tele pickup and mounted it inside a small metal box with in/out jacks. Its purpose is to use when I need to convert the low impedance output of my signal generator to something more resembling a guitar's characteristics.

You could have used a small signal transformer. That would have stepped up the output.
A pickup won't do anything in this regard.

For best hum rejection, use two wires (signal and gorund) to the input and twist them tightly together. Same for the output. You already mentioned that you would be shielding it too, so that's good.

http://www.muzique.com/lab/pickups.htm

Twisting the wires only serves to act as semi shielded cable. It will not reject hum from the pickup coil. Shielding also won't do it. This is why humbuckers were invented. And they were used years before showing up on guitars for inductors.



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