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previous: Dave Stephens ONe of the things about resonant pe... -- 1144981315 View Thread

Re: Wait a second

4/13/2006 8:05 PM
moocowRe: Wait a second
The measurement issue is just a second reason why the resonant frequency number is not too useful. To me, the best reason to ignore is that this type of resonant frequency is dependent only upon the pickup inductance (which we can measure reliably) and the winding capacitance. The winding capacitance is very small so we get a high resonant frequency in the 10-12kHz range. This resonant frequency measurement is really an indicator of the winding capacitance, which itself has no effect on the sound of the pickup (the cable capacitance overwhelms the winding capacitance).  
 
Once the pickup in wired up and plugged into an amp, the cable capacitance overwhelms the winding capacitance and causes the resonant frequency to drop to the 3-4kHz range. This 'in-circuit' resonant frequency can be measured using the direct drive method (the one I like) as well as the drive coil method (the one everyone else on the planet likes). Unlike the 'pickup-only' resonant frequency, the results will be the same in both cases.  
 
This in-circuit resonant frequency is the one we actually hear. We can't hear a pickup that isn't plugged into anything so we never hear that 10kHz resonant frequency. As it is, it is hard to measure correctly and get a number that high. The in-circuit resonant frequency is the one that is relavant, but it is deternmined by the pickup inductance and the cable capacitance. I keep having to say this, but the only contribution the pickup makes to this resonant frequency is the *inductance*. The DC resistance, winding capacitance, and eddy current losses do not affect the location of this resonant frequency. This is why it is ok to ignore that 'pickup-only' resonant frequency, but it is *not* ok to ignore pickup inductance.  
 
Chris Kinman has some information about these two types of resonant frequency on his website. He makes the distinction between the two, but Seymour Duncan does not. I think this is a misleading thing to do but then again, he's the one who's making money by selling pickups, not me.

 
Replies:
David Schwab [QUOTE]This in-circuit resonant fre... -- 4/18/2006 10:31 AM