What contributed to the unique tone of a Telecaster? Several factors contribute to the tone such as Body, Pickups, Electronics, Hardware, etc. Today let's talk about the most obvious factor-Pickups.
First, we can clearly see that the cover of the pickup from Telecaster is copper-nickel alloy. Secondly, we can see that the Telecaster uses a brass base plate. These two distinguish points caught my attention. In order to understand what the designs are for, and what difference does it make on the tone, we did an experiment.
One of the most critical parameters that determine the pickup is the resonant frequency F (F↓, the lower the tone, F↑, the brighter the tone.) The size of the resonant frequency is determined by the capacitance C and the inductance L together, the formula is
(1) When a copper casing is added to the outside of the pickup, the most significant effect is that the output power of the pickup is reduced, which is related to the shielding effect of the copper material on the magnetic field.
As shown in the figure above, the output amplitude of the pickup on the left side is the output with the shell added, which is obviously smaller than the output without the shell on the right side.
(2) Although the copper casing does not have magnetic permeability, when the external magnetic field changes, for example, when the string vibrates, there will be induced eddy currents. The effect of eddy current will hinder the change of magnetic field to a certain extent. Make the output sound of the pickup become softer and more pleasant. When the metal casing is added, the magnetic field eddy current distribution diagram is shown below.
(3) The the copper casing can make significant change on the inductance value of the pickup. Based on my knowledge on the filter circuit, this will have a certain filtering effect on the frequency. The following table shows the comparison of with and without the copper casing.
|
Pickup style |
|
Inductance Value |
Magnetic field strength (6 strings) |
Resonant frequency |
|
Tele |
With Copper Casing |
2.47H |
1097GS |
6.25Khz |
|
Without Copper Casing |
2.55H |
1122GS |
5.7KHz |
|
|
|
Quality factor |
Bandwidth |
Capacitor |
|
|
With Copper Casing |
1.478 |
4228hz |
263pF |
|
|
Without Copper Casing |
1.887 |
3020hz |
306pF |
We can see that after installing the copper shell, the inductance value goes down, the resonance frequency goes up, the bandwidth becomes more , and the tone will sound more full-bodied.
2.The effect of brass base on tone:
Through experimental simulation and actual testing, we found that when the brass base is added, the inductance L of the pickup is greater than without the base. When L↑, the resonance frequency F↓, and the tone becomes relatively low and deep.
This magnetic field vector distribution diagram is when the iron added at the bottom of the pickup:
When the copper added at the bottom of the pickup:
In summary, in addition to the body and the pickup itself, a more important influence on the phoneme is its shell design. The sound of the tele pickup with the cupronickel shell is softer and more pleasant; the brass base makes the magnetic field distribution tighter and the output fuller. This is the source of tele's unique voice. You can pick up the pickup and switch a shell of different material for it, maybe you will get some interesting sounds!
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