Potting and Covers
It should be mentioned here that Seth Lover’s original humbucking design called for a nickel-silver metal cover to protect the coils and further shield the unit from noise. While making history with John Mayall and the Bluesbreakers, Eric Clapton for some reason decided to remove his covers. In a magazine interview he stated, “I have removed the metal covers from my pickups and the sound is fabulous.” Clapton could not have known that the pickup’s cover causes stray capacitance, which cuts a bit of the high-end off the pickup’s sound and increases upper harmonic content. Removing them opens up the pickup.
Another byproduct of the cover removal craze was that players discovered the plastic bobbins on some pickups were black, while others were cream colored. Of course, Eric’s were cream colored and sounded better. The truth of the matter is that cream colored and black colored plastic should not sound different, but the timeframe and run of pickups in which they were made could be different. During the second run of PAF pickups, Gibson ran out of the black plastic and used the cream color, thinking no one would ever see under the cover. They were still making some slight changes during that time that may have resulted in the reported sonic differences.
As gain levels began to increase, microphonic feedback became a problem.
Caused by the windings literally vibrating against each other, high-pitched squealing could occur. Potting or impregnating the coils with wax or other materials was nothing new, but the original humbucking pickups were not potted. I remember Eddie Van Halen saying in old interviews that he dipped the pickups in hot wax and “watched the coils melt.” Most pickups these days are potted in some fashion, but don’t try this at home!
The Birth of Active
While the replacement pickup market was booming, the options available to guitarists remained passive pickups with a variety of winds and magnets. At the time, a big focus was on having the power to push that Marshall into massive overdrive with loads of sustain and harmonics – amps didn’t have overdrive channels like today.
That’s when EMG entered with a radically new design: a coil and magnet- based pickup with one additional component – an internal preamp. New engineering techniques allowed for any amount of output, while the tone and frequency response could be shaped to the designer’s taste. The windings and magnet strengths could be minimized, limiting magnetic string pull and enhancing sustain.
At first people were a bit hesitant to accept these new pickups – called “active” pickups – that required a battery inside the guitar. But some players quickly found the benefits to far outweigh the problem of battery replacement. The first model – the 81 – is still the most popular active pickup in the world, used by many great players such as Zakk Wylde and Kirk Hammett. The need for a more vintage-style pickup produced the model 85. EMG has continued to design new models in both humbucking and single-coil varieties. The single-coil types can be made to cancel hum, and can have their circuitry tuned for single-coil tones. Additionally, it is possible to add other onboard circuitry to create just about any type of tone you wish, proving why active pickups remain a popular choice among those seeking out higher gain and specific tones.
Over time, the technology behind active pickups has branched out to combine the tonal benefits of single-coil pickups – spanky highs and lows, perfect for blues and country – with the reduced hum and higher gain of active systems. EMG’s S and SA models have become very popular with players looking to bridge both worlds. While purists may argue over whether or not these souped up designs sound like traditional designs, they certainly have their place – in situations requiring low noise, for example.
A Note on Electronics
It’s important to remember that your pickups do not work alone – they work in conjunction with the electronic components in your guitar. Pots and capacitors play an important part in the sound of your pickups. For example, EMG pickups are shipped with the proper pots (25k) and they must be used with this value; that said, you can feel free to experiment with the tone capacitor values to change your tonality. Another popular trick with active pickups is to install two batteries in parallel to increase current to the pickups, providing a bit more tightness and punch.
With passive pickups, the general rule is 500k pots for humbucking pickups and 250k pots for single-coils. This is not a hard and fast rule, however. Generally, the higher the impedance of the pot, the more highs are allowed through. If you have installed a humbucker and found it to be a bit too bright or brittle, changing from a 500k to a 250k pot might just do the trick. P-90 style pickups offer another example – I have heard them sound great with either value pot. Also, don’t forget 1 Meg pots. In the sixties, Fender began to install 1 Meg pots on Telecasters. Certain country artists were looking for bright, twangy Tele tones and this pot value did the trick. I have also seen seemingly dark humbuckers scream with harmonics while using this pot. It is important to remember that there are no rules here – use what you like. Pots are an inexpensive, simple way to experiment with your tone.
So Which Pickup Should I Choose?
It’s a question I’ve heard thousands of times, and likely the reason that you’re reading this article. Because the pickups are such an integral part of your tone, and linked in with every other component of your guitar, I usually decline to answer until I have the following information:
- The type of guitar, including woods, bridge and scale length
- The type of amp(s) employed
- The type of pedals used, especially overdrives
- The musical styles played with the guitar
- What exactly the player wants this guitar to do as far as versatility and range of tones
Remember, that no one guitar can do everything perfectly.
But if you find yourself waffling over the decision between active and passive pickups, you can generally assume that active pickups will have more bite, more sustain and more output. While it may be a generalization, active pickups are usually the best choice if you’re looking to pummel the front-end of your amp with the largest signal possible. While passives are generally more organic and interact more with your amplifier, it would be a mistake to assume that passive pickups are not capable of beefy signals. While there are numerous “vintage-style” pickups on the market, featuring more traditional outputs, there are likewise a new cadre of passive pickups available capable of throttling your amp just as effectively as an active humbucker.
Remember that with today’s amps, it is not really necessary to have a pickup with tons of output. That very same DiMarzio Super Distortion that drove those old non-master volume Marshalls into overdrive in the seventies may not be the right choice for your Bogner Ubershall. I recommend selecting a pickup that has the tone and harmonic content you are looking for, then cranking up the gain to whatever level you wish on a modern amp. If you are using an amp such as Retro King, Doctor Z, a Fender Reissue or any other non-master volume amp, pickup output may still be an important factor in your decision.
Although there are many advertisements out there showing artists endorsing certain pickups, remember that the artist has made their choice of pickups by taking into consideration how they sound through their gear. The signature models of a pickup really reflect the artist’s setup. Many players buy a pickup because they want to sound like their favorite player. It is far better to discover whatever pickup and gear that gives you the sound you hear in your head. Let your own ears do the deciding – don’t let some online forum or doctored sound clip decide for you. A little patience and an open mind will reward you with that glorious, gritty tone you’ve always been looking for.