### Post by pasqualino on Oct 22, 2020 17:40:53 GMT -5

I'm modelling everything like I always do, but in this case I attempted to stay on topic with the pickup/guitar modelling. The pickups are of great importance because you can't effectively simulate a stomp box if you use the std "ideal" AC source from SPICE or Micro-Cap. The simulation is worthless without having a proper model for the source series L and R and loop shunt C of the coils. Your case-study of a post is testimony to this.

I was wondering if it's possible to take a data sheet for a given pickup and plug new calculated parameters into the model.

This may have to be done empirically, but it would be nice if this data were available straight from the manufacturer or even if it could be calculated from the data sheet. To do it empirically, you might as well have them installed and pick out every note and take measurements. What's the alternative, buy a pickup, blast a optimally loud chirp at it, measure the response and then return the purchase?

I'm presenting an over complicated description and didn't mean to. I just want to have "reasonable" values for the model parameters of any given pickup. The AC resistance is easy to model in Micro-Cap since you only need to plug the equation for resistance as a function of f into the Freq field of the resistor. What equation is the real question. The L, C and DC resistance are

relatively frequency independent, but the AC resistance is an order of magnitude greater than the DC resistance because the loss in the magnets is is significant. It's an entropy thing...

Okay, I'm doing it again, sorry.

There has to be a straightforward way to get the parameters for the AC resistance. The structure for the pickup is consistent and we can easily calculate L, C and R

So I take what I said at the beginning of the previous paragraph back, there probably isn't a way to easily determine the parameters for magnetic loss unless the manufacturer tests the magnets in the lab and hands you a number or at least curves for changes of frequency at a few fixed values for intensity and visa-versa.

Probably a case of over analysis, I'll just fudge some reasonable equation in the freq field of the resistor model in Microcap and make adjustments. When in doubt, just guess a ballpark solution and iterate, right?

I'll shut up now.

I was wondering if it's possible to take a data sheet for a given pickup and plug new calculated parameters into the model.

This may have to be done empirically, but it would be nice if this data were available straight from the manufacturer or even if it could be calculated from the data sheet. To do it empirically, you might as well have them installed and pick out every note and take measurements. What's the alternative, buy a pickup, blast a optimally loud chirp at it, measure the response and then return the purchase?

I'm presenting an over complicated description and didn't mean to. I just want to have "reasonable" values for the model parameters of any given pickup. The AC resistance is easy to model in Micro-Cap since you only need to plug the equation for resistance as a function of f into the Freq field of the resistor. What equation is the real question. The L, C and DC resistance are

relatively frequency independent, but the AC resistance is an order of magnitude greater than the DC resistance because the loss in the magnets is is significant. It's an entropy thing...

Okay, I'm doing it again, sorry.

There has to be a straightforward way to get the parameters for the AC resistance. The structure for the pickup is consistent and we can easily calculate L, C and R

_{DC}from the data sheet. I've never seen specs for anything other than R_{DC, }Turns, wire gauge, insulation etc. Nothing regarding magnetic losses though. Maybe they exist and I just missed it. Now that I'm thinking about it, the distance between the strings and magnets in the pickup will vary and that's probably a square law thing regarding the intensity of the vibration of the magnet. Both intensity and speed (frequency) of vibration would contribute to magnetic loss.So I take what I said at the beginning of the previous paragraph back, there probably isn't a way to easily determine the parameters for magnetic loss unless the manufacturer tests the magnets in the lab and hands you a number or at least curves for changes of frequency at a few fixed values for intensity and visa-versa.

Probably a case of over analysis, I'll just fudge some reasonable equation in the freq field of the resistor model in Microcap and make adjustments. When in doubt, just guess a ballpark solution and iterate, right?

I'll shut up now.