There are two common methods used. 1) sensing films or “transducers” mounted either under the bridge saddle, or 2) applied to the underside of the top or “soundboard.” And both of these systems can be either “passive” or “active” the difference being that the “active” system has the addition of a pre-amp and battery boost. The active system has become the most popular today, and again modern electronics has produced the warmest, cleanest, and most natural sound ever achieved.
One form of acoustic amplification is the use of a Microphone, a small miniature condenser type of “mic” placed inside the instrument. Actually, microphones were the original method of amplifying an instrument, either standing or sitting next to a microphone. The major problem associated with the use of a mic, both in the past and today, is feedback, causing irritating tones from amps, especially at high volume. We have experimented with many different types of internal microphones, and have now discontinued their use, especially with the advancement in modern pickup technology.
The electromagnetic pickup is another form of amplification of stringed instruments. This is actually an electric guitar pickup, modified for use on acoustic instruments. The same “coiled” pickup is mounted or straddled between the sound hole, and vibration from each string is “electromagnetically” transmitted to the magnetic coils within the pickup, then transferred to an end jack and then to the amp. The sound is very clean and clear, and will not produce any feedback. However, this pickup is not often used for two reasons. One, a pickup mounted within the sound hole detracts from the appearance and obstructs acoustic tones escaping via the sound hole. But a more important reason that this pickup is not chosen is because it sounds like an electric guitar pickup, which to some, defeats the purpose of having an acoustic guitar. Again, modern “transducer” technology has opened up many more options for creating a warm, clean, clear amplified acoustic instrument, with much less feedback than was possible in the past.
Since most acoustic amplification will be saddle transducers, let’s briefly discuss under-saddle transducer installation. The secure contact of the saddle plays an important role in sound transmission. The vibrating string transmits to the saddle, next to the bridge wood, then to the top wood, sends vibrations along braces, all of this is bouncing between the sides, top, and back, and eventually “jumps” out the sound hole. So the tighter and more solid the footing of the saddle, the better the transmission. However, if the saddle is too tight it does not make adequate contact with the sensing strip that was embedded underneath. Sound complicated? It is. And sometimes frustrating, even for the tech doing the installation. To illustrate, if a saddle pickup is chosen, the saddle is, in a sense, resting upon a “pillow” and string tone vibrations must pass through this pillow layer first before reaching any other material of the instrument. So this is a very critical area of sound transmission.
We have, in the past, installed “active” soundboard transducers, transducers that “stick” on the inside of the instrument, and have included and mounted inside a pre-amp. We have discontinued this installation. We continue to install undersaddle passive transducers. This pickup may also be connected to an external outboard preamp for enhanced tone and volume.
– Transducer strip installed under the bridge saddle. No pre-amp or battery. No on-board controls.
$150.00 (parts and labor)
NOTE: a preamp is not necessary, however in high volume settings an external outboard preamp will convert a “passive” system to “active” and greatly enhance tone and volume.
#1 – L.R. Baggs Undersaddle Transducer (designed for Ko’olau) with internally mounted volume control (accessible at sound hole area). Preamp and battery are mounted inside instrument.
$250.00 (parts and labor)
#2 – L.R. Baggs Undersaddle Transducer with preamp manufactured into the endjack. No volume control. No battery required. Recharging is accomplished by plugging endjack into an AC outlet. AC plug included. This is labeled as the “MiSi” pickup.
$250.00 (parts and labor)
Ko’olau Guitar & ‘Ukulele Company
Pono Guitar & Ukulele
401 N. Cane Street, A-10
Wahiawa, Hawaii 96786
(808) 622-1064 • Fax: (808) 622-1646