Impedance 101

[thehangingmist]

What is impedance? Is it like resistance?
When i wire two pickups in series, is the new impedance the sum of both the individual impedance values?
And when wired in parallel?

Low impedance pickups don't work well without a preamp? What is the ballpark value below which u know u will need a pre?

 

[line6man]

Impedance is the opposition to alternating current. It is a vector sum of resistance (opposition to the flow of current) and reactance (from energy stored in inductive and capacitive components.)

For series components: ZTotal​=Z1​+Z2​+...Zn​
For parallel components: ZTotal​=1/([1/Z1​]+[1/Z2​]+...[1/Zn​])

Low impedance pickups are uncommon, but don't necessarily need preamps. Certain Gibson pickups come to mind. The greater concern is output level.

 

[thehangingmist]

Impedance is the opposition to alternating current. It is a vector sum of resistance (opposition to the flow of current) and reactance (from energy stored in inductive and capacitive components.)

For series components: ZTotal​=Z1​+Z2​+...Zn​
For parallel components: ZTotal​=1/([1/Z1​]+[1/Z2​]+...[1/Zn​])

Low impedance pickups are uncommon, but don't necessarily need preamps. Certain Gibson pickups come to mind. The greater concern is output level.

thanks!
i was hardly able to get any put from these unknown soapbars i have but with a pre they are quite ok. Cannot figure out what's the reason to that! These cannot be active pickups for sure!

 

[line6man]

thanks!
i was hardly able to get any put from these unknown soapbars i have but with a pre they are quite ok. Cannot figure out what's the reason to that! These cannot be active pickups for sure!

If you're trying to measure pickups, a standard Ohm meter will give you a measure of resistance to direct current. It's difficult to determine the impedance of a pickup, because reactance is frequency dependent.

In any case, active pickups often have a rather high resistance (EMGs can be around 60k Ohms.), despite their low output impedance, when powered. The easiest way to spot an active pickup, however, is to check for a positive DC supply lead.

 

[thehangingmist]

thanks!

 

[Ric5]

Remember 8 ohm plus 8 ohm = 4 ohm.

 

[walterw]

Remember 8 ohm plus 8 ohm = 4 ohm.

in parallel;

in series, 8Ω + 8Ω = 16Ω. (call me captain obvious!)