User manual FENDER AMERICAN STANDARD GUITARS

[. . . ] Conveniently shock-mounted to the back of the preamp case, the microphone is acoustically isolated inside the instrument, providing freedom of movement as well as minimal leakage from other instruments on stage. 2 ACOUSTIC GUITAR SYSTEM QUICK START To successfully combine microphone and pickup signals, it is best to start by presetting the microphone EQ to control feedback, then mixing in the pickup. The PREFIXTM ONBOARD BLENDERTM features three ways to control feedback; a PHASE switch, NOTCH filter and semi-parametric CONTOUR controls. Follow these steps to achieve a strong, feedback-free microphone response. Before plugging in, set all controls as follows: · NOTCH and VOLUME fully counter-clockwise · All EQ sliders at center position · BLEND slider at MIC position 2. [. . . ] Slowly increase the VOLUME until the guitar and speaker are approximately the same level. Leave the switch in the position that sounds the deepest and clearest. Slowly increase the volume until the instrument starts to rumble or howl with low to mid level feedback (100-200 Hz). Slowly increase the VOLUME again, until you hear a squeal (high frequency feedback). Slowly adjust the Contour FREQUENCY slider until the feedback is eliminated. Raise the CONTOUR Level slider (if possible) to just below the threshold of feedback. The pickup signal will add significant attack and definition to your sound. Double check the PHASE switch position until you find the clearest response. See diagram on page 6 3 FISHMAN PREFIXTM ONBOARD BLENDER PREAMP FUNCTIONS BATTERY COMPARTMENT Pull the small tab at the top of the ONBOARD BLENDERTM toward you. The body of the preamp will swing out, revealing the BATTERY COMPARTMENT. Insert a fresh 9V alkaline battery. MICROPHONE TRIM 9V BATTERY PREFIXTM SERIES PREAMP GUITAR BODY MICROPHONE TRIM CONTROL A small circular potentiometer is located on the underside of the preamp just below the battery compartment. A simple way to determine the quality of phase (in or out) of two sounds is to compare phase switch settings at low volumes. IN PHASE In phase is when the waveforms of two sounds originating from the same instrument are similarly aligned in time. Similar phase is like looking at yourself in a mirror: your reflection directly follows your movement. OUT OF PHASE UPPER PEAK Out of phase is when the waveforms of two sounds originating from the same instrument are aligned such that the upper peak of one wave occurs at the same moment in time as the lower peak of the other. Out of phase is like looking at yourself in a live LOWER PEAK video monitor; the image you see is similar, but the perspective is shifted. When you move to the right, the image appears to move to your left. 8 ACOUSTIC GUITAR SYSTEM WHY DO I NEED A PHASE SWITCH ? The phase switch is useful for two reasons: 1. Due to the interactive and changing nature of phase, acoustic amplification depends on maintaining optimum phase relationships between amplified instruments, sound systems and venues. Since an industry standard for polarity has not been established for all sound equipment, the phase switch can compensate for any unintentional differences that might occur between instrument and sound system. APPLICATIONS In any situation where the mic'ed instrument faces a loudspeaker, there will be an interactive phase relationship between the two. This usually occurs with stage amps, side fill and floor monitors at close distances. · LOW VOLUME AMPLIFICATION At low volumes, when a mic'ed instrument and speaker are at similar levels and are in phase, the sound is full and solid, with the lower frequencies emphasized. When a mic'ed instrument and speaker are out of phase at low levels, the bass frequencies cancel out to some extent. The resulting sound is somewhat unnatural and unbalanced compared to in phase. · HIGH VOLUME LEVELS At high volume levels, when a mic'ed instrument and speaker are in phase, the sound pressure from the speaker will excite the instrument's sound chamber, creating a feedback loop at the instrument's lowest octave. [. . . ] · HIGH VOLUME LEVELS At high volume levels, when a mic'ed instrument and speaker are in phase, the sound pressure from the speaker will excite the instrument's sound chamber, creating a feedback loop at the instrument's lowest octave. This "cavity resonance" feedback can be dealt with by putting the mic'ed instrument and speaker out of phase or by adding equalization. Inverting the PHASE switch will put the mic'ed instrument and speaker out of phase with each other, cancelling the low frequency feedback. If you move from your position on stage more than a few feet, you may have to invert the PHASE switch again to maintain an out of phase relationship between the mic'ed instrument and speaker. Continued . . . 9 FISHMAN PREFIXTM ONBOARD BLENDER Continued from Page 9 Here's why: A typical guitar has a cavity resonance of about 100 Hz. [. . . ]