Laserfiche WebLink
MULTI-PURPOSE SOUND SYSTEM <br />Section 16780 <br />15-1207 <br />ensure that all systems are free from spurious oscillation and radio frequency pickup <br />and shall correct any such defects. <br />E. Loudspeaker Polarity: Check the Polarity of the loudspeaker lines with an Acoustic <br />Polarity Tester. All loudspeaker lines shall be identically polarized with respect to color - <br />coding such that absolute polarity is maintained. <br />F. Freedom from buzzes, rattles and objectionable distortion: Apply a slow sine wave <br />sweep from 50 Hz to 5 kHz at a level of 6 dB below rated power amplifier output <br />voltage, to each system and listen carefully for buzzes, rattles and objectionable <br />distortion (each major loudspeaker zone shall be tested individually). Correct any <br />causes of these defects, unless the cause is clearly outside the sound amplification <br />system equipment and installation, in which case bring the cause to the attention of the <br />Owner. <br />G. Gain control settings: Establish tentative normal settings for all gain controls and <br />measure system gains at 1 kHz. Adjust all gain controls on rack -mounted equipment <br />for optimum signal to noise ratio and signal balance and, unless they are sub -panel <br />mounted, cap them to prevent tampering. Unless specified or instructed otherwise, <br />adjust gains such that in a given system the "front end" maintains 10 dB of clip margin <br />referenced to the first onset of clipping of the associated power amplifier(s). Settings <br />may require further adjustment by the Contractor as a result of testing by the <br />representative of the Architect. <br />3.10 SYSTEMS PERFORMANCE TESTING AND ADJUSTING PROCEDURES: <br />A. Individual Equipment Items: Test, measure, adjust and document the performance of <br />each individual item of equipment provided herein to demonstrate that it equals or <br />exceeds manufacturer's published specifications or the specific applicable portion of <br />these specifications, as applies. Tests shall be performed only on items that have been <br />substituted for items listed in these specifications. <br />B. System Performance: System interconnection devices, cables, methods, procedures, <br />shall not result in degradation of performance parameters of individual equipment <br />items. <br />C. Test Procedures, Audio: <br />Electrical tests: <br />a. Gain at 1000 Hz <br />b. Maximum.. Output <br />C. Input Clipping Level <br />d. Frequency Response <br />e. Total Harmonic Distortion <br />f. Signal to Noise Ratio <br />g. Signal to Crosstalk Ratio <br />2. Electro Acoustic Tests: <br />a. Uniformity of coverage; utilize a source of octave band pink noise centered <br />at 1 kHz and 4 kHz, with representative measurements made at ear level <br />26 <br />