User manual RANE MH 4

[. . . ] OPERATORS MANUAL MH 4 HEADPHONE AMPLIFIER QUICK START Conect the output from any stereo source such as a mixer or tape deck, and plug the left and right inputs into the respective INPUT jacks. The Inputs accept balanced or unbalanced sources. This source is now routed to each of the four Outputs. For a single mono source feeding all headphones, connect it to either one of the INPUT jacks and engage the STEREO/ MONO switch. [. . . ] 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. Another way to create the necessary isolation is to use a direct box. 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. This is a dangerous and illegal practice. 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. Since most equipment is not internally grounded properly, connecting both ends of the shield is not often practiced, since doing so can create noisy interconnections. A common solution to these noisy hum and buzz problems involves disconnecting one end of the shield, even though one can not buy off-the-shelf cables with the shield disconnected at one end. The best end to disconnect is a matter of personal preference and should be religiously obeyed; choose inputs or outputs and always lift the side you choose (our drawings happen to disconnect the outputs). If one end of the shield is disconnected, the noisy hum current stops flowing and away goes the hum -- but only at low frequencies. A one-end-only shield connection increases the possibility of high frequency (radio) interference since the shield may act as an antenna. Many reduce this potential RF interference by providing an RF path through a small capacitor (0. 1 or 0. 01 microfarad ceramic disc) connected from the lifted end of the shield to the chassis. The signal takes on a flat-topped, or clipped shape. When an amplifier tries to go above its max power, it clips. compressor A signal processing device used to reduce the dynamic range of the signal passing through it. For instance, an input dynamic range of 110 dB might pass through a compressor and exit with a new dynamic range of 70 dB. The modern usage for compressors is to turn down (or reduce the dynamic range of) just the loudest signals. Other applications use compressors to control the creation of sound. [. . . ] Varies widely, from very low mic-levels to quite large line-levels. limiter A compressor with a fixed ratio of 10:1 or greater. The dynamic action prevents the audio signal from becoming larger than the threshold setting. Linkwitz-Riley crossover The most preferred active crossover design. [. . . ]