Rickenbacker pickups

[Les]

Oh, quitcher rantin' possum.

You said it was useless and I'm just trying to give you something that isn't.

We used virtually an identical SPICE analysis at Shure decades ago to make literally millions of high impedance, humbucking, alnico 5 and 9 fitted phono cartridges.

At least you don't have to mess with #54 wire!

We used resistive loading and little brass shorted turns (slipped over the coils) to control the upper peak.

It's real. Believe it. It's what a kid plugging his guitar into a fender will hear. You'll like it later!

[David Schwab]

Great stuff for thought here!

This thread is getting interesting.

I think there is self inductance and capacitive effects going on between turns... it would be cool to measure and chart these kinds of things, which in turn could help show how they affect (or not) the tone of the pickup.

Does it make sense to characterize transducers by their conducted
impedance curves yet ignore their transducted energy curves?

Does it make sense to test a transducer according its sensitivity to
a local energy field such as time-varying sound pressure or magnetic flux?

Gedanken experiment:
If you constructed a guitar pickup, e.g.,
a single PAF coil of 65 layers at 65 winds/layer,
as a stack of 65 spiral winds instead of 65 layers,
would it make a difference?

If such a pickup were mounted in a strung and tuned guitar,
would the magnetic flux be the same through all spiral layers?

Would the winds at the top experience more flux than the bottom ones?

If the magnetic flux varies along the vertical axis of the coil...

-drh

[Les]

David,

Yes, it is good to have tools to understand the sonic significance of the electrical parameters.

The spice models I did and impedance runs are inherently linear operators, but pickups are inherently non-linear devices.

However spice is fully capable of non linear analysis. It could even do time delay comb filter effects from wide or spaced pickups. Hysteresis, non-uniform fields, frequency dependent resistance, capacitance, and inductance... it can do all of that. But even the linear model is close.

To broadly answer salvarsan's Gedankin experiment I could just say this:

1) pickups are very very loosely coupled magnetic circuits.

2) e=d(Ba)/dt

3) pickup output drops off if it is moved away from the string and

4) stack humbuckers work real good.

So anyway I was asked to do this tester bit by folks not on this thread. I said I would, and did. I have some contractural obligations to deal with here, so I have to kinda go away now. I gave Scott the spice circuit files to play with.

I hope this helps you guys!

[soundmasterg]

Possum, I didn't mean to imply that there was something wrong with your method of testing the resonant frequencies, I just figured with these suggestions we could get it to display more of a peak and make it a bit more useful. If I get the time, I'll check with some engineers here at work and see if a current source amplifier of sufficient design can be cobbled up for not too much scratch.

Les, I'm glad you were able to build the device that you were after. Personally I'd just use the toasters, but then I'm going to be switching the higains from my 330/12 BBR into my 360/6 BBR and putting the toasters in the 12. The higains sound good but the toaster sound is what I'm after in the 12. I'll be trying some TI flats too on it. Have fun with yours!

So anyway I was asked to do this tester bit by folks not on this thread. I said I would, and did. I have some contractural obligations to deal with here, so I have to kinda go away now. I gave Scott the spice circuit files to play with.

Thanks for dropping by Les. This a cool forum with a lot of interesting info on it. We can always use someone with your knowledge and good humor so I hope you can drop by from time to time and contribute. David Schwab is another RIC user here besides me, and Sergio from the RIC Resource forum is a regular here too, so you're among friends if you get the time to hang out.

4) stack humbuckers work real good.

Maybe, but they sound like crap!

Greg

[David Schwab]

Maybe, but they sound like crap!

Crap is such a strong word!

I prefer side by side coils for humbuckers, but I have to say I've heard some very nice stacked pickups in recent years.

I like the stacked Tele lead pickup I made.. sounds like a Tele, even though I was trying to go for something else. lol

They don't sound exactly like single coils though.

[Possum]

splicey tomatoes and spice....

the splice program wouldn't be useful to me really. How would you program in say, a steel core humbucker bobbin 1/4 inch thick with a certain radiused ends, half inch tall, 1018 steel, tape insulated, aluminum bobbin top, paper bobbin bottom, 5,000 turns of 44 heavy formvar? Impossible :-) You just have to make it and listen to it. Sure, then you could make a chart but it would only be useful if you make a variant of the prototype to compare it against.

As far as sharp peaks on a chart, pickups don't have sharp peaks, I think the guys who get that are using an impedance method or something, like those college kids are using, its not really a frequency response chart. I tried Joe' Gwinn's multimeter method to identify resonant peaks once and what I ran into is that most pickups had such slow curved peaks that you couldn't really identify some of them. Espescially hand wound pickups have smoother peaks than machine factory wound stuff.

Heck, if someone wants to build something I could use for cheap I might be interested, even if I had to use on a PC (the world's dumbest machines....). I was thinking of buying Mac The Scope at one point, a very expensvei Mac software but after trying the demo found out it wasn't any more useful than the freebie FuzzMeasure I was already using.