Info from EMG Site ...
EMG's are easy to install. Each pickup features EMG's own Quik-Connect header and mating cable for quick installation. Included with each pickup are pre-wired volume and tone controls, battery clip, output jack, and diagrams. All models are designed for direct replacement into most standard instruments. There are instances where "direct" replacement isn't possible, but a minimum of work should be required.
There is no other pickup built as well as an EMG. The coils are precision wound, matched both resistively and inductively, and finally, vacuum sealed. All internal preamplifiers are Surface Mount Technology (SMT) for quality and reliability. Each pickup is tested for audio quality and reliability before encapsulation and again before shipment.
The first choice in design is the string interface. The selection of a bar magnet or individual pole pieces is also an important one. All initial EMG designs use a bar magnet for two reasons - Pole pieces place too much magnetism under the strings and cause the lower ones (primarily low E, A, and D) to go "out of pitch" with a Doppler effect. This is especially true of the Fender Stratocaster* where 3 poles under each of the strings push and pull them through a variety of unnatural movements. Poles can also make intonation and tuning difficult. On the other hand, pole pieces have the benefit of a percussive attack giving the pickup much more of a "plucky" sound.
Designs featuring a bar magnet have a much more linear (balanced) output from string to string. Its attack is less pronounced than the pole piece design resulting in smoother distortion, and much better sustain. String bending is smoother because the output doesn't fade when you bend strings. By relying on the internal preamp for gain the bar magnet can also be smaller, further limiting the magnetic "pull" on the strings. And, the continuous magnetic field of the bar allows for any string spacing. Perfect for any multi stringed instrument, and the less conventional instrument.
Most EMG Pickups use a magnetic bar. Single coil pickups are available in both bar and pole-piece designs. There are fewer negative attributes to the bar and it's preferable, but if you like pole-pieces for your playing style then there is an EMG model for you.
It's not really necessary for a pickup to have a magnet at all, but it helps. The magnet acts as the juice for the signal flow. The shape and type of magnet used in each EMG Pickup is different. Ceramic magnets don't affect the inductance of the coil but have a much stronger magnetic field. Alnico material exhibits less magnetism yet greatly increases the inductance of the EMG design. Each has an affect on the resultant output and frequency response of the pickup. The addition of steel poles (either bar or screw/stud) increase the inductance of the pickup design and further change the results.
Tall and skinny, short and squat, long and wide, every EMG Pickup has two and they are the basis of each EMG. There are different types and sizes of magnet wire that can be used, combining their attributes with the shape of the coil has a tremendous affect on the tone. A long, skinny coil will have more resistance yielding less low frequency response, while a short, squat coil will have less resistance, and more inductance.
It's a balancing act to achieve the style of tone you want. In all cases, EMG Pickups have two coils. This is necessary for noise reduction, while providing the vehicle for the distinctive EMG tone. Coils are sometimes placed side by side, or stacked, but in both cases each coil is treated independently by the preamp. Instead of having the coils in series or parallel with a single output, they are electronically summed so their attributes can be controlled individually.
The preamplifier used inside each EMG Pickup is no ordinary preamp. Built directly into each pickup, the preamp is an integral part of the pickup design assuring quality of sound performance, incredible noise reduction, and simplicity in installation. It provides a variety of benefits for us as the designer and for you as the player. A natural by-product of the preamp is gain. It allows us to design a pickup for its particular tone without concern for the pickup's output. After the coils have been modeled, any amount of output needed is available from the preamp.
One of the most important aspects governing the tone of a pickup is the resonant frequency. EMG Pickups use "Impedance Modeling" to manipulate the two coils. This innovation allows us to shape a mix of the reactive slope and resonance from each of the two coils. The idea is to achieve a complex mixture of each coils phase and frequency response resulting in a richer tone from the pickup. This means the sound is vibrantly alive with more harmonics than from conventional passive pickups. EMG Pickups like the EMG-S, EMG-SA, and the EMG-60 use this technique to its fullest, while the EMG-81 uses modeling in only a small way. Modeling might work well for a single coil pickup, but not for a design such as the EMG-ACS Acoustic Sound Hole Pickup. As each pickup design is approached differently, it all depends on the final result we're searching for.
Another benefit from the internal preamp is noise reduction. By integrating the preamp into the housing, all the elements of the pickup can be shielded. By matching the coils to a high degree, the low frequency hum and buzz are virtually eliminated. In addition, each EMG is housed in a composite cover cap that eliminates all other forms of interference. Most EMG Models have noise figures of better than -85dB, still other EMG Pickups achieve a noise figure that exceeds -100dB. All the internal components are fully vacuum-sealed and encapsulated in epoxy to prevent microphonic noise and to increase long-term reliability.
Low Impedence Output
The low impedance output of the EMG internal preamp provides other great features. You can run a cable for up to 100 feet (30 meters) without losing high frequency response. You'll also be able to get the same tone with a wireless unit as you do with a cable. The tone of your instrument will remain consistent when you change the volume control as well. Not only can you plug directly into your favorite amp, you can go direct to tape preamp (especially for acoustic guitar recording) or direct to a mixing console input without a direct box. You can plug into any portable cassette recorder, or even your home stereo auxiliary input, and play your instrument with incredible results.
An instrument equipped with EMG Pickups requires power from a single 9 Volt battery. With two EMG Pickups installed, your instrument draws about 160 microamps of current. Even if you play eight hours a day, this small amount of current drain means that a battery will last up to a year. A single 9 Volt battery will power as many EMG Pickups and Accessory Circuits as you can fit in your guitar. Power to the pickups is turned off by unplugging the guitar cable from your instrument.