LMA8 Mic/Line Preamplifier
8
Remote ground connection
The balanced instrument/line input of the LMA8 opens up the unique possibility to use a pseudo balanced configuration
with instruments like guitar, bass etc. The configuration will cancel out a large portion of the electrical noise induced in the
cables. This is quite advantageous when using long cables on stage or in an electrically noisy environment near light
dimmers or near high power mains installations.
A guitar or bass hook-up is a high impedance system, and as such, it is very sensitive to electrical interference. Using a
balanced cable instead of a single core cable, introduces one additional wire to "receive" the environmental noise. This
additional noise signal is fed into the balanced input of the LMA8 at the negative input terminal, canceling out the noise
signal at the positive terminal without affecting the sound signal from the instrument.
The configuration will in most cases give a substantial noise reduction, depending on the electrical characteristics of the
instrument pick-up. The two signal lines are terminated by different impedances at the instrument and at the preamp input,
so a total noise cancellation will not take place. As a minimum, a noise reduction of at least 10 - 15 dB should be
expected.
Note that the noise from the instrument pick-up is not reduced. Only the noise induced into the cable is affected.
