I started designing and building custom pickups in 1974 when I met Bill Lawrence. Also, thanks to Rick Turner for sharing many years of working together. Over the years, I have seen many forms of guitar pickups enter the marketplace as both aftermarket items and standard factory issue. What I've come to recognize most is to meet the needs of the individual and not try to influence them with anything except a little education.
Guitar pickups sound the way they do for many scientific reasons but the actual tone comes about because of their interface to the next stage of electronics. This can be an amplifier, console, or several stages of signal processing.The actual job of the pickup designer is to try to design pickups that will sound the same in any of these circumstances. That isn't so easy, but by understanding AC theory and by stacking up years of listening, it can be done. At Lawrence Sound Research back in 1975, we did what I consider the most complete testing of pickup design and configurations. Over the years, I have made and rewound hundreds of pickups, mostly on a custom basis, but also to provide coil taps and custom switching.
The PowerPlant line of pickups came about as a desire to create my own pickup for the APACHE line of solidbody electric guitars. I also offer this design as an aftermarket pickup for both single coil and humbucking replacements. The PowerPlant pickups are a low noise, high Q, low Z, high output design with ceramic magnets. I compare the sound they have to an old Gretsch guitar with heavy strings!! That means lots of presence, power, and clarity. They are passive design pickups and don't use batteries.
There are two main sources of electrical hum and buzz in electric guitar and bass systems, and both enter through the pickups and electronics. The sources are AC electrostatic fields and alternating electromagnetic fields radiated from electric wires, lighting dimmers, fluorescent light ballasts, power transformers in amplifiers et cetera.
Pickup coils and unshielded wiring in guitars act as very effective antennae that capture these radiated fields and pass the unwanted hum on along with the guitar signal.
With powerful modern amplifiers, multiple gain stages for distortion, and external effects, the hum problem really gets out of hand. If you are playing at 115 dB on stage, the hum can easily be at 85 dB, giving you only a 30 dB signal to noise ratio! These are not exactly studio specs...
Many musicians try to lessen the problem by using noise gates; unfortunately, noise gates seem to create as many problems as they solve by messing with the dynamic range of the intended signal. The best solution is to try to fix the problem in the signal chain as early on as possible. That means the instrument should be upgraded.
The two sources of hum, electromagnetic and electrostatic, manifest each in its own way. Electromagnetic noise shows up as a 60 Hz hum (annoyingly close to B flat), and its intensity changes as you turn the instrument towards or away from hum sources such as amplifiers.
Electrostatic noise shows up as a buzzing sound, occurring somewhat at 60 Hz, but more at the 120 and 180 Hz harmonics. This is the noise which occurs when you take your hands off the strings of your instrument (assuming that the strings are grounded).
Fortunately, there is a cure for each type of noise.
ELECTROMAGNETIC NOISE AND HUMBUCKING
Unfortunately, there is only one way to get rid of electromagnetic noise and that is by humbucking. A single coil pickup intercepts radiated magnetic fields very effectively, and cannot differentiate between the string signal (picked up as a magnetic field signal) and hum.
With humbucking, two matched coils are connected together out of phase. The out-of-phase hum fields thereby cancel each other out. Thus, the external fields do not interact with the pickups own permanent magnetic field. To pass the desired string signal in phase, the polarity of each coils permanent magnetic field must be reversed. This results in two 180 degree phase shifts which add up to 360 degrees; this puts the string signal back in phase.
The humbucking pickup, invented by Seth Lover of Gibson in the early 1950s, does a great job of getting rid of hum. The humbucking configuration is also inherently efficient as a pickup design; hence it has become known for its powerful and fat sound. However, there are sounds which you just cant get from the classic Gibson humbucking configuration.
To a large degree, the shape of a pickups magnetic field determines its sound. Therefore, no changes to the coils or magnet types will give a single coil sound to a Gibson-style humbucker.
If you are playing a guitar with single coil pickups, there are options which allow hum cancellation. A common solution is to use after-market pickups such as Duncans, EMGs, or Ultra Sonics which buck hum with two coils while having close to a single coil sound (see our Service Bulletin on pickups).
Another solution is to modify pickup polarity and wiring so that some of the combinations of pickups become humbucking. We often flip the polarity of the center pickups on Strat-style guitars so the two combination settings of the 5 way switch (neck + middle & middle + bridge) become very effective humbucking positions. In doing this, there is absolutely no discernible change in tone.
This can also be done to one pickup in a Tele, giving humbucking to the middle position. We did this to Bernie Leadon's 56 Strat and his two 53 Telecasters, and when we asked him how he liked it his reply was, "I didn't notice".
That is, of course, the whole point! If the hum isn't there, you wont notice it.
ELECTROSTATIC NOISE AND SHIELDING
Electrostatic hum and buzz entering a system from your instrument can be totally eliminated by 100% shielding of the pickups and control cavities. Usually, somewhat less than 100% will do an adequate job in guitars, which are inherently hard to shield; but the more complete the job, the better the results.
The whole idea behind shielding is to completely surround all circuit "hot" leads with a low resistance conductive cage which intercepts electrostatic fields and grounds them out. Just as one would not use unshielded "Zip" cord as a guitar cable, one shouldn't put up with an unshielded guitar.
We use a combination of conductive paint and adhesive copper foil to shield pickups and control cavities, making sure that there is a minimum resistance path to ground for all the shielding. We have encountered shielding jobs done by other shops where the shield is not connected to ground; this can actually make the noise problem worse!
We also carefully insulate any signal points which could short out to ground; unfortunately, many guitars are not designed to be shielded, with "hot" points of the circuitry too close to the cavity walls.
The following is a description of various shielding jobs commonly done in our shop:
PROCEDURE:
We lay down a copper tape ground drain in the body under the pickups, in the control cavity, the jack cavity, and on the underside of the pickguard. Then we paint all cavities (pickup, control and jack) with conductive paint, test for continuity, and repaint if necessary.
We take off the pickup covers, lay in a tab of copper tape, and paint the insides of the covers; we then run separate shield ground wires from the pickups to ground.
On Strats, we commonly flip the polarity and wires of the center pickup, giving humbucking in the two combined pickup positions on a five position switch. This has absolutely no effect on tone and is a real winning trick.
SHIELDING: $90
FLIP CENTER PU MAGNETIC FIELD (RWRP) $45
PROCEDURE:
Body cavities and pickguard as per a Strat. Many players donut like the neck position pickup cover as it adds to microphonics and squeal; taking it off, however, unshields the pickup. To take care of that problem as well as the bridge pickup, we wrap copper tape around both pickups, connecting the tape to ground with separate wires.
The Tele bridge pickup is mounted on a large steel plate, which helps shield it as well as acting as an inductive load. This gives the pickup that characteristic ëtreblyí tone.
Our procedure gives about 80% shielding coverage to the pickups and 100% to the controls. We can flip the polarity and wiring on the neck pickup giving about 90% humbucking in the both pickups position.
SHIELDING: $75
FLIP NECK PU MAGNETIC FIELD: $45
PROCEDURES:
Gibson has been very inconsistent in its shielding; some years they did a great job, requiring no further work from us, and some years they didn't do much at all! When Paul's do need shielding, we follow the same procedures on body cavities as with Strats plus shield the backplates. If the humbuckers don't have covers, we wrap the coils with copper as per Teles. Gibson has always used very well shielded cable, so no problems there.
SHIELDING [BODY CAVITIES]: $60.00
SHIELDING [PICKUPS]: $20.00
MODELS: GIBSON 335s, 345s, 355s, LUCILLE et cetera.
EPIPHONE SHERATON / CASINO
GRETSCH COUNTRY GENTLEMAN et cetera.
PROCEDURE:
On most of the simpler ësemi-hollowí guitars, shielding jobs are usually not absolutely needed and are a great pain to do! Companies generally use shielded wiring with a minimum of exposed (hot) wiring points.
On the Lucille, Gretsches and other instruments with removable backplates, we can do a great shielding job. Some of these have a lot of circuitry (Varitones, multiple tone switches, etc.) which can attract noise, and with these guitars we advise shielding.
SHIELDING: $90--$150
FENDER JAZZ AND PRECISION BASSES
PROCEDURE:
As per Strat with regards to control pockets and pickups. Fender did make some attempt at shielding basses using brass ground plane plates under the pickups and in some control pockets, but it is not adequate, especially given Fender's use of unshielded wire. The ëPí Bass pickup is humbucking, and the ëJí pickups are when both are turned up, so there's nothing to do there.
SHIELDING: $90
The procedures listed above apply to most other instruments, and costs will stay in line with those quoted.
If you have an unusual instrument which hums and buzzes, bring it in and well give you a quote!