A post on fb by Phil Jones

[Chris P.]

Pickups and electrical output variation.

I was intrigued to see just how much variance there is on pickup output from a few passive basses I had at hand today.
So first I needed to see what the peak output would be obtained by plucking a single string hard and then setting up my analyzer and my custom pickup transducer to provide a constant alternating magnetic field, that would be the equivalent of the peak output from a single string plucked exactly the same time over and over again and that would be an impossible task.
I will dig into this deeper with more measurements sometime in the future but I thought I would just give a snippet of my preliminary results.
The test frequency was done at a frequency of 500Hz because all pickups are flat from 20Hz to 1000Hz. so it gives a level playing field to all pickups. The output was measured with a calibrated Fluke AC voltmeter. All pickups were connected to their pots and output was from jack out on instrument with volume at max and tone on full treble. In other words; the complete instrument with volume and tone on full.

Jazz Bass American Std 5 String -228 millivolts
Precision Bass American Std 5 String- 396millivolts
Telecaster Bass with Seth Lover designed Humbucking neck (Chrome )pickup 621millivolts.
Precision Bass with Lace Aluma-tone split Pickup -283 millivolts.

This is not the maximum pickup output that can be produced from the pickups. In fact the Telebass could peak than over 1 volt with more than one string plucked.

I used the same procedure to measure the output of my custom Ken Lawrence 6 string bass with Bartolini's (which I always considered having a very hot output.) That with the same 500 Hz tone induced into the coil, put out 2230 mV. That is almost 10 times the output of the passive Jazz Bass pickups!

This is just to give an idea that pickups have a huge variation and if you add a pre amp in the bass than that can be a magnitude of ten times greater output. This does not take in strings and they have variation due to the iron mass in them. And that does not include playing style.
Passive controls also will cause output fluctuation. Example the voltage output of the neck pickup on the Jazz Bass dropped by almost half when the neck pickup was turned up. So the pickup is influenced by the other.
.Another thing was that there were minor variations in output of exactly the same pickups and from neck to bridge pickups and even between the split pickups on P Basses. The reality is that this would not be noticed audibly as the variation was around 10-25mV and that is way less than a single dB in variation. Even it was I am pretty sure that players would subconsciously compensate with their own technique.
If anyone has any questions/comments please post it

[Dave W]

The output figures don't surprise me at all. What is surprising is his claim that "all pickups are flat from 20Hz to 1000Hz." My ears tell me otherwise.

[amptech]

Pickups and electrical output variation.

The test frequency was done at a frequency of 500Hz because all pickups are flat from 20Hz to 1000Hz.

Are you shure about this? I was not aware. I must admit that pickups is not my main field, but I do wind a good bunch of them and
did do a lot of research before I started doing this about 10 years ago. The natural resonance frequenzy of coils is determined very much
by the number of turns, and I'm aware this usually lies above 1khz. If this resonance frq. is low, the pickup will be more 'bassy' sounding and
vice versa. I would just assume that a pickup with a resonance frq. below 1khz is not flat at all around this point?

It is nice reading anyway, this post!