So what exactly is needed to make this graph?

[ModulusMK]

Of course, but the high end I think is somewhere similar.
However, can you scan the pages of the book with pup info construction?

[Bruce Johnson]

Maybe I'm missing something in the discussion.....

I understand about the spectrum analysis software measuring the output of the pickup. But what are you using to drive the pickup? Is it in a guitar, and you're picking a string? Are you creating a sweeping field over it?

[belwar]

Maybe I'm missing something in the discussion.....

I understand about the spectrum analysis software measuring the output of the pickup. But what are you using to drive the pickup? Is it in a guitar, and you're picking a string? Are you creating a sweeping field over it?

BINGO.

Thats the million dollar question..

Im guessing there are several parts to making a graph like this..

1 - An oscilloscope.
2 - Some form of driver .. something that creates a uniform signal that can be produced the same over and over again.

What type of driver could be used? What would be an example?

[David Schwab]

Go to post #10 and read what Dave wrote. That's one way to do it. The other way, you put the pickup right into the circuit.

[Possum]

.

Helmut Lemme, read his translated article on pickups and how to use a driver coil. I think its the best way because putting the pickup IN a circuit is actually changing things, you're not actually reading what the pickup by itself is doing. If you're reading a pickup IN a guitar you're also getting a picture of your guitar, change guitars and you won't get the same results. this is sort of required reading in pickups 101, third classroom on the right, down the hall:
BuildYourGuitar.com :: The Secrets of Electric Guitar Pickups

[Possum]

..

I see he has a new version of his pickup analyzer, I emailed him once trying to get a price, no answer. He also added some comments about how humbuckers function and the difficulty of reading them. Very cool....

[belwar]

Ahh that mythical device.. If you ever get a price, or find out about it let me know. I dont think they exist..

So I get what I have to do know is build a driver.. and finish the work for gundry. the SOB is a slave driver.

[Joe Gwinn]

I see he has a new version of his pickup analyzer, I emailed him once trying to get a price, no answer.

I recall that it was 1,000 Euros, which at current exchange rates is about $1,500, exclusive of shipping and taxes.

[JGundry]

Ahh that mythical device.. If you ever get a price, or find out about it let me know. I dont think they exist..

So I get what I have to do know is build a driver.. and finish the work for gundry. the SOB is a slave driver.

Slacker.

[Yves]

Yes the pickups are bright, these are blade pickups with not alot of wire on them. I don't think it makes a huge difference what software you use as long as you use it and only it for everything you measure. Fuzzmeasure will do a log sweep, MLS and MLS pink noise filtered. I'm using a 50 ohm drive coil the way Lemme shows and just the standard Mac in/out's. This was one of the few times I found any use for frequency analysis, I had two prototypes that sounded similar and I needed to know something about what was going on...

But I think your set up might not be ideal (correct me if I am wrong): if you are driving your coil with the standard Mac out, your are driving the coil with a voltage generator (I assume your sine sweep is constant in amplitude throughout the frequency?).
But the coil impedance makes the current flowing into it frequency dependant.
And the magnetic field produced by the coil is proportional to the current flowing into it.
So you are producing an exciting field that is frequency dependant, which is not exactly what you want (i.e. your are not only ploting the pickup frequency response curve, but also the exciting coil response).
You would need a "calibration file" (something like with acoustic software and measurment mic) to "reverse match" the coil influence and produce a constant field throughout the frequencies, or drive the coil with a constant current. Lemme states it actually, that he needs to drive the coil with a constant current source, hence his "black box" I guess.

Well, as long as you use this to compare pickups, you've got an idea of what's going on, but not an absolute measurement IMO.

[Bruce Johnson]

But....If you use a driver coil like Lemme does, doesn't that take the pickup's magnets completely out of the test? If the driver coil is creating a sweeping cyclic magnetic field, which the pickup's coil is detecting, would any changes in the pickup's magnets make any difference in what you'd read on the spectrum analyzer? It seems to me that a driver coil setup could be useful for comparison testing of pickup coils, but not of much value for testing the complete pickup.

Or am I completely missing something here?

[Yves]

But....If you use a driver coil like Lemme does, doesn't that take the pickup's magnets completely out of the test? If the driver coil is creating a sweeping cyclic magnetic field, which the pickup's coil is detecting, would any changes in the pickup's magnets make any difference in what you'd read on the spectrum analyzer? It seems to me that a driver coil setup could be useful for comparison testing of pickup coils, but not of much value for testing the complete pickup.

Or am I completely missing something here?

Yes, I think you are right indeed: the exciting coil not only modifies the magnets field but also must intoduce mutual coupling with the pickup coil.

Anyway, for sure, such a setup is usefull for testing and comparison, but it doesn't replace a string vibration.

[Possum]

...

Yeah my setup is probably a bit crude but there really is no standard way to do this even at higher levels and expensive gear. That college that did a physics course on pickups came up with their version, very complex. If you only use one method and know what the results mean and keep it constant is all that matters. The driver coil needs to be low impedance, I used 38 gauge wire if I remember and only about 50 ohms. Yes the magnet is involved, you are exciting a coil that is butt up against the magnet in the field of the magnet so of course what magnet you have in there has a direct effect on what your graph will show.

[David Schwab]

Since we just discussed 'scopes, this very thing was talked about.

Take a look at Daniel's post here:

http://music-electronics-forum.com/t15048-2/#post120063

That's how he derived the graph he posted.

[Possum]

....

Here's a quick and dirty comparison of slug coil and screw pole coil on a '63 early Patent. Guess which is the slug coil? BTW, my driver coil is being driven by an amplified speaker for computers , not straight out of the Mac as I said before, crude but it works fine enough for my purposes. I'm actually setting up to do some experiments using this stuff since the LCR meter doesn't see very well in the higher frequencies...