Assessments - 4, GPA: 3.5
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Facilidade de uso
3 1. THE CONTROLS........................................ 4 2. USING THE MIXER......................................13 2-1-0 Signal-to-noise ratio................................13 2-2-0 Using the Mixer controls............................15 2-3-0 The VU meters....................................17 3. RECORDING WITH A FOUR CHANNEL TAPE DECK ..........19 3-1-0 Priliminaries......................................19 3-2-0 Recording.......................................21 3-3-0 Mixing down.....................................23 3-4-0 Adding more voices................................24 3-5-0 The four channel tape deck alone.....................26 4. CAUTIONS.............................................28 4-1-0 The reverberation unit..............................28 4-2-0 The PAN POTs....................................28 4-3-0 False stereo......................................28 THE LAST WORD ................................29 SPECIFICATIONS ................................30 INDEX TO TERMS................................31 Copyright © 1976 by ROLAND CORPORATION All rights reserved. No part of this publication may be reproduced in any form without prior written permission of ROLAND CORPORATION. INTRODUCTION Although it is designed as a part of the ROLAND System 100, the Model 103 Audio Mixer can be used in almost any situation where a four channel mixer is needed. A glance at the front panel will show that the operation of the Model 103 Audio Mixer doesn't present many problems, so this manual has been divided into three main sections. Section 1 is a breif description of the controls and their function. Section 2 contains a few more details on certain points. Section 3 gives a few notes on using the 103 Mixer in conjunction with a four channel tape deck for making synthesizer tapes. / I 1.THE CONTROLS page 5 page 6 The POWER switch 5 The Output Jacks The INPUT section The EFFECTS INPUT section 8 The EFFECTS OUTPUT section 9 The OUTPUT section % ^ i*. , Ni-s» «■T .. •V - * . 10 The VU meters The MONITOR LEVEL 12 2. USING THE MIXER The following are some points which will help you get more out of your mixer and related equipment. 2-1-0 Signal-to-noise ratio All electronic equipment generates a certain amount of noise. This noise, highly amplified, is the source of noise in the NOISE GENERATOR. Electronic circuits are also designed to take a certain level of signal (sound, in the case of audio equipment) with a minimum of distortion. For ease in calculations, this level is called "0" (zero). This is the meaning of the "0" on VU meters. Values above this "0" are "+" (plus) values (usually red on VU meters), and values below are " (minus) values. These values are measured in units called decibels (dB). (The bel is named after Alexander Graham Bell of telephone fame). The signal-to-noise (S/N) ratio for the Model 103 Audio Mixer is: "more than 60dB" (SPECIFICATIONS, P. 30). (Sometimes S/N is expressed as a negative value: —60dB, but the meaning is the same). This means that the level of the noise generated by the circuits is lower than —60dB in relation to the "0” reference level. A S/N value of 50dB would be considered from fair to good in hi-fi equipment for home use; 60dB is considered quite good. Values higher than this take you into the relm of professional equipment and this is one of the reasons for its high cost. 2-1-1 Dubbing losses..... When dubbing (copying) a tape, you lose a certain amount of sound volume and sound quality. How much you lose depends a great deal on the quality of the tape decks and mixer, the quality of the tapes used, and the recording and play speeds used. For the following discussion, we will assume a loss of 3dB. Fig. 2-1a shows a signal recorded with the high points at about OdB ("0" on the VU meter) on a tape deck with a S/N of 55dB. Copying this recorded signal onto another tape using a tape deck of similar quality produces the result shown in fig. 2-1 b. The noise already on the original tape combined with the new noise from the second tape deck produces a loss of 3dB; in other words, the noise level has risen 3dB to —52dB. 13 Fig. 2-1 Dubbing losses 0. ©. Fig. 2-2 Low level signal losses ®. ©■ 2-1-2 Recording levels..... Fig. 2-2a shows a signal which has been recorded at about —25dB for a pp effect. The difference between the noise level and the signal level is about 30dB. (In other words, the S/N for this recorded signal is about 30dB). If you changed your mind and decided to copy the tape in fig. 2-2a so as to produce a signal of OdB iff), you would be amplifying the noise as well as the signal and the result would be to drag the noise level up to —27dB (fig. 2-2b). With the signal at OdB iff), this noise may not be able to be heard, but it definitely would be very noticeable during any rests in the passage and during the silence before the passage starts and after it ends. This is why recording levels should b...