Notoriously quiet instruments, violins can easily be overpowered by the more boisterous sounds of drums, electric guitars or even powerful vocals in contemporary music. To compensate for this, choosing a good violin pickup is essential. The primary factors to consider when choosing your violin pickup are how the pickup attaches to the instrument and the kind of transducer it uses.
Some varieties of violin pickups attach to the bridge or clamp on to the body of the instrument. These tend to be the easiest type to install, but the contact with the violin body may dampen the resonance quality slightly. They can be moved to specific locations on the instrument for variations on tone production, such as under the lower strings to amplify the tone of lower notes or under the higher strings to amplify the upper register. Many of these models can be easily used with a standard acoustic violin.
Other types of pickups actually replace the bridge of the violin. They may contain individual transducers for each string or a single transducer for all strings. Since they measure the vibration of the strings directly at the bridge, which is where the sound is produced in the instrument, bridge-replacement pickups produce the tone quality that is most similar to an unamplified acoustic violin. They are also the least likely to produce feedback — the squealing or screeching noise that comes from the microphone picking backup sounds from the speaker. Since there is no variation on the placement, a bridge-replacement violin pickup tends to produce the most consistent tone quality.
Even though they offer several benefits, bridge units still have limitations. Certain models are designed only for an electric violin and cannot be fitted to a standard acoustic violin. If you want to move back and forth between amplified and natural sound, a different type of violin pickup might a better option for you.
The next factor to consider is the type of transducer the violin pickup uses. Simply put, a transducer converts one type of energy into another type. In the case of a violin pickup, a transducer converts the mechanical or electromagnetic vibration of the strings into electrical impulses, which are then converted to an amplified sound.
One popular type of acoustic violin transducer is the piezoelectric transducer, which measures the mechanical vibration of the string. These tend to have the best sound quality from lower strings, but may sound thin or weak in the higher strings. When used with a high-quality preamplifier, a piezoelectric transducer tends to produce the purest sound.
The other common type of transducer is the electromagnetic transducer, which is similar to an electric guitar pickup. Measuring the electromagnetic impulses given off by the vibration of steel strings, electromagnetic pickups are highly sensitive and can produce a wide dynamic range. Compared to the sound of an acoustic violin, the tone produced by an electromagnetic transducer may have a tinny or mechanical sound. Whether this is preferable to the more open sound of an acoustic instrument depends on the type of music you want to play as well as your own personal preference. These transducers may accidentally transmit other electromagnetic signals like those of cell phone transmissions due to their sensitivity.