Impedance vs. Volume

[m_charles]

hi!

I am trying to educate myself on impedance. I read RG's article, I think I'll grasp it all after I read it 100 times more, but for now a simple question.

In general, "impedance and volume are two different subjects, but they are related" would be a true statement, correct?

If I said, "my pick-up has lower volume (output) therefore it has low-impedance", would NOT be a correct statement, correct?

Simply put, high impedance does not mean high output and low impedance does not mean low output, correct?

thank you in advance!

chuck

[John Lyons]

For the most part impedance and output level are not related.

john

[calpolyengineer]

Impedence is the analog of resistance for AC circuits

-Joe

[R.G.]

In general, "impedance and volume are two different subjects, but they are related" would be a true statement, correct?

I think 'intertwined' or 'involved' would be more accurate than 'related'. It's almost impossible to have a discussion of audio volume without referring to impedances at one point or another, but they are very different issues.

If I said, "my pick-up has lower volume (output) therefore it has low-impedance", would NOT be a correct statement, correct?

You are correct; pickups having lower volume does not necessarily mean they have lower impedance, although lower impedance -is- one explanation for why a pickup might have low volume. Could also be weak magnets, distance to strings, a partial internal short, an external loading, etc, etc.

In fact, the statement is just about backwards. It probably is accurate to say "My pickup has a low impedance, therefore it has a lower volume, all other things being equal."

Simply put, high impedance does not mean high output and low impedance does not mean low output, correct?

No, it does not.

However ( you knew this was coming, right?  )
In the world of electromagnetic pickups, the output voltage is directly related to the number of turns. The number of turns has some bearing on the length of wire the pickup is wound with, and that adds resistance with every turn. More importantly, it adds inductance proportionately with the square of the number of turns. This is assuming everything else is held the same, of course. Electromagnetic pickups have an output voltage proportional to magnetic strength and the velocity of the moving parts, too, so you have quite a few variables to jigger around.

So in guitar pickups, a pickup with fewer turns has a lower resistance and maybe a much lower inductance. The output voltage goes down linearly with the number of turns, the pickup impedance is primarily inductive, and decreases with the square of the turns change. And in some cases, yes, it appears that low impedance pickups have low output, and high impedance pickups have high output. But there exists a slew of other caveats, such as at what frequencies.

You're very close to understanding. I tip my glass to you.