102

Appendix E: Best Grounding Practice

Balanced transformers

Active electronic circuits achieve good results, but for ultimate noise rejection, transformers are needed. Transformers colour the sound especially at low and high frequencies due to core saturation and impedance rises. They are also expensive, so they are typically only used as external problem solvers when all else fails.

Screen termination

Sometimes ground loop currents are so strong that even balanced systems can pick up some noise. This is because the currents manage to find a way into a piece of equipment’s internal unbalanced circuits. This is easily cured by breaking the screen ground connection, so that it is only connected at one end of the cable. Opinions as to which end to break differ within the audio industry but:

•Induced noises in electronically balanced systems are typically best rejected by input stages, so breaking the ground there will generally give the best audio performance. This also allows any common mode AC currents from the output driver to return via the screen ground to their source rather than finding a longer path through the power cables, which may give rise to noise or crosstalk elsewhere.

•Alternately, breaking the screen connection at the send end provides a much more practical grounding scheme if cables are to be hot plugged. Then any cables that are plugged first (that is, only) into an input will have a screen and thus will not be a source of severe electromagnetic interference (which would be the case without the screen connection).

•If a transformer is utilised within the balanced connection the best CMRR performance will be obtained by breaking the screen ground at the transformer end of the cable.

With long cable runs, sometimes the impedance of the screen conductor is high enough that disconnecting one end allows some electromagnetic interference through the screen onto the signal conductors. This is typically audible as stray local radio transitions, typically at very low levels. If this is a problem, it can be cured by bridging the break in the screen connection with a capacitor. This improves the screen at high frequencies, but maintains the isolation that breaks ground loops at lower frequencies. 10nF to 50nF are good values to use and are available in ceramic packages that are small enough to fit inside connector shells. Some experimentation may be necessary, especially if multiple cables are bridging two units, because in this case the capacitors are effectively connected in parallel and their combined value will grow (for example, 32 channels at 50nF will equate to 1,600nF). It is probably better to use 10nF for this kind of multiple connection, so that the overall value only grows to 160nF.

Source

Destination

Screen

+

+

-

-

Chassis

Chassis

Screen termination diagram showing screen broken at destination

VeniceU Operator Manual

Page 111 Page 113
Page 112
Image 112
Midas Consoles U24, U32, U16 technical specifications Balanced transformers, Screen termination
Page 111 Page 113

U32, U24, U16 specifications

Midas Consoles has firmly established itself as a leading brand in the professional audio equipment market, particularly known for its innovative mixing consoles. Among its impressive lineup, the U series, including the U16, U24, and U32 models, stands out for their remarkable features and cutting-edge technologies that cater to both live sound and studio environments.

The Midas U16 is a compact yet versatile mixing console, offering 16 input channels suitable for various applications. Despite its smaller footprint, the U16 does not compromise on sound quality or functionality. It features high-definition preamps that ensure clean and transparent audio, while its processing engine allows for dynamic EQ and multi-effects, providing audio engineers with creative flexibility. The console comes equipped with an intuitive user interface, featuring a touch screen and easy-to-navigate controls, facilitating quick adjustments during performances.

Moving up in size, the U24 model provides 24 input channels, expanding the mixing capabilities for larger productions. The U24 retains the same premium-quality preamps as the U16, ensuring that every microphone and instrument connected to it is captured with precision and clarity. This model enhances the user’s experience with additional routing options and more extensive onboard processing capabilities. The inclusion of a dedicated effects engine allows for real-time manipulation of audio, making it ideal for live sound situations where adjustments need to be made on-the-fly.

At the top of the range, the U32 offers the ultimate in power and flexibility with 32 input channels. Designed for larger venues and complex audio setups, the U32 is equipped with additional features that cater to professional audio engineers' needs. This console includes advanced digital snake technology, allowing for seamless integration with stage boxes and remote connect capabilities. Furthermore, the U32 can support various plug-ins, making it versatile for different genres and sound profiles.

Across all models, Midas Consoles emphasizes robust construction and reliability, ensuring longevity and peak performance even in demanding environments. The range features a wealth of connectivity options including USB interfaces for direct recording and playback, as well as extensive routing possibilities to accommodate diverse setups.

In summary, Midas Consoles' U16, U24, and U32 models represent the epitome of modern mixing technology, characterized by their exceptional sound quality, intuitive interfaces, and comprehensive features tailored for professional audio applications. Whether it’s an intimate gig or a large festival, these consoles provide the tools needed to deliver outstanding audio experiences.
Top Page Image Contents