User manual RANE MQ 302S

[. . . ] OPERATORS MANUAL MQ 302S STEREO GRAPHIC EQUALIZER QUICK START If this is your first equalizer, please do yourself and your speakers a favor and read at least the first five pages. The MQ 302S is a stereo equalizer, so adjusting any slider affects both channels simultaneously. Begin by setting all sliders to their center detent (0 dB), and the INPUT LEVEL to its center detent (0 dB). After equalizing, use the EQ switch to compare equalized and non-equalized signal. [. . . ] Analyzers consistently and accurately "tell it like it is, " but ultimately, personal judgment determines what sounds good or appropriate. In fact, final optimum EQ settings, made after analyzer testing, will vary greatly depending on the type of music, sound pressure level, size of the venue and disposition of the audience. Conclusion: To consistently obtain the best sound from your system, use an analyzer and then your ears, in that order. The analyzer supplies the consistency and calibration while your ears supply the good taste. Manual-5 SOUND SYSTEM INTERCONNECTION Rane's policy is to accommodate rather than dictate. However, this document contains suggestions for external wiring changes that should ideally only be implemented by trained technical personnel. Safety regulations require that all original grounding means provided from the factory be left intact for safe operation. No guarantee of responsibility for incidental or consequential damages can be provided. (In other words, don't modify cables, or try your own version of grounding unless you really understand exactly what type of output and input you have to connect. ) THE ABSOLUTE BEST RIGHT WAY TO DO IT Use balanced lines and tie the cable shield to the metal chassis (right where it enters the chassis) at both ends of the cable. A balanced line requires three separate conductors, two of which are signal (+ and ­) and one shield. The shield serves to guard the sensitive audio lines from interference. Only by using balanced line interconnects can you guarantee (yes, guarantee) hum-free results. Chassis tying the shield at each end also guarantees the best possible protection from RFI [radio frequency interference] and other noises [neon signs, lighting dimmers]. THE NEXT BEST RIGHT WAY TO DO IT The quickest, quietest and most foolproof method to connect balanced and unbalanced is to transformer isolate all unbalanced connections. The goal of transformer adaptors is to allow the use of standard cables. With these transformer isolation boxes, modification of cable assemblies is unnecessary. Virtually any two pieces of audio equipment can be successfully interfaced without risk of unwanted hum and noise. Originally named for its use to convert the high impedance, high level output of an electric guitar to the low impedance, low level input of a recording console, it allowed the player to plug "directly" into the console. Now this term is commonly used to describe any box used to convert unbalanced lines to balanced lines. THE LAST BEST RIGHT WAY TO DO IT If transformer isolation is not an option, special cable assemblies are a last resort. The key here is to prevent the shield currents from flowing into a unit whose grounding scheme creates ground loops (hum) in the audio path (i. e. , most audio equipment). Do not be tempted to use 3-prong to 2-prong "cheater" adapters to lift grounds. It is true that connecting both ends of the shield is theoretically the best way to interconnect equipment ­ though this assumes the interconnected equipment is internally grounded properly. [. . . ] headroom The level in dB between the typical operating level and clipping. For example, a nominal +4 dBu system that clips at +20 dBu has 16 dB of headroom. hum Unwanted sound contaminating audio paths due to EMI (electro-magnetic interference) caused by AC power-lines & transformers getting into unbalanced, poorly shielded, or improperly grounded connecting cables. Hum has a definite smooth (sine wave) repetitive sound based on the harmonics of 50/60 Hz such as 100/ 120 Hz and 150/180 Hz. [. . . ]