Technology: The Basics of Choosing and Using Racks for Installation



By Geoff Meads, Presto Audio Visual If you think about it, home technology devices have come full circle. The very first radios, televisions and stereos were essentially pieces of wooden furniture. I can clearly remember one grandfather's 'Sunshine' radio and the other's 'sideboard' music centre, both resplendent in real wood casework. Indeed, our family's first PYE colour TV was finished in finest faux teak wrap. While it was the fashion to have technology out on display through the 1980s and 1990s, now the trend is back to hidden technology. With many technical toys being odd shapes and sizes (I'm looking at YOU, network router manufacturers!) hiding them away can be simply a matter of good taste. [caption id="attachment_910" align="aligncenter" width="483"] Even if hidden in a cupboard, would this give your client the impression of a professional job? (Image courtesy of Your Smart Home - a project they were called in to rescue).[/caption] Good aesthetics are only one of the reasons why proper mounting and cable planning of electronic equipment is an important part of overall system design and installation. Serviceability, upgradability, physical stability, user interaction and thermal management are all concerns when choosing an equipment mounting regime, and each area must be considered in detail, especially for larger systems. [caption id="attachment_911" align="aligncenter" width="300"] Good aesthetics are only one of the reasons why proper mounting and cable planning is important. (Image courtesy of Grahams Hi-Fi).[/caption] Design Considerations Let's look at each of the above in a bit more detail. 1) Serviceability No product is perfect. Things can and do go wrong and, if they do, you, the installer, will need to get to the item in question and, at the very least, have good enough access to test, diagnose and rectify faults. Any rack used will need to allow this for all equipment within it. 2) Upgradability We live and work in an ever-changing world of technology. Connections, formats and user needs change all of the time. Rack choice and planning will need to allow for access to equipment for software or hardware changes over time. 3) Physical Stability A lot of the equipment we install, particularly big AV receivers and other audio amplifiers, can be heavy - very heavy in some cases! These pieces must be carefully placed so as not to turn the rack into a potential tip hazard. You might also need to need to tie a rack to the back wall to prevent tipping, especially if the rack is on rails. 4) User interaction Items as if CD, DVD and Blu-ray players and games consoles need constant user access. In these cases, we need to understand who might be using the device. If a games console or disc player is to be rack-mounted, it will need to be placed low enough for the kids to reach it to change discs. 5) Thermal Management Heat is the biggest killer of electronic devices. While analogue equipment is generally more resilient to high temperatures than digital, all electronic equipment must be kept at a reasonable temperature to ensure long-term reliability. If heat is an issue in the rack then a temperature-controlled, active cooling system (thermostatic fans to you and me) must be designed in, and have adequate airflow and ventilation to remove hot air and replace it with cooler air. Rackable equipment A lot of electronic equipment used in CI is designed for rack mounting. That means it is designed to fit in an industry-standard-sized rack and secured by bolts at either end of the front plate. The rack fixing point on the equipment can take different forms. The first comprises a flat front plate that is an integral part of the equipment design, and this extends beyond the sides, with holes for the mounting bolts. The second comprises additional 'ears' that can bolted onto the sides of the equipment, again with mounting holes. The third comprises a separate tray that bolts into the rack and provides a shelf for the actual kit to sit on within the rack. [caption id="attachment_912" align="aligncenter" width="378"] Music server with rack ears attached.[/caption] Standards The good news is that rack size is standardised, not just across the CI world, but also across a whole host of other professions. Pro sound, IT, broadcast and networking engineers all use the same 19" racks, meaning we have a huge array of racks and rack accessories to choose from. The height of equipment designed for rack mounting is also standardised into the 'U' (unit of 1.25 inches or 44.45mm). 1U is 1.25 inches high, 2U is 2.5 inches high and so on. We don't even need to remember the actual height in inches or millimetres since both equipment height and rack height are specified in Us as standard. 21U of equipment, vent space and spacer panels, all of which will contribute the total space needed, will require a 21U rack. Simple! Rack Types The smallest common rack type is the wall-mounted rack. These are often used for IT systems and networks in small or home offices. Space is limited to 12U or so in height and about 150-300mm in depth. Weight capacity is also limited due to the necessity for wall hanging. [caption id="attachment_913" align="aligncenter" width="250"] A wall-mounted rack typically used for the small/home office.[/caption] Next is the open floor-standing rack. These are simply constructed and often shipped as a flat pack for construction on site. They are cheap, simple and light, but offer very little security, no control of heat and can look messy in domestic environments. Then we have the floor standing, enclosed rack which is also often delivered as a flat pack. These are better than the open racks for heat management, security and keeping out dust, damp and family pets! They can still look a bit 'industrial' unless soffit-mounted into a wall or kept in a machine room. Most of the basic rack types look a bit industrial, but there are a number of manufacturers that produce better-looking systems, specifically for the residential market. Custom cut rack shelves with special front panels are also available to tidy up equipment that isn't expressly designed to be rack mounted. [caption id="attachment_914" align="aligncenter" width="300"] A good-looking custom rack cabinet. (Image courtesy of Finite Solutions).[/caption] Cabling One of the hidden advantages of mounting in a rack is that cabling can be run up each side at the back then across horizontally to the intended piece of equipment. Cable trays or tie bars can be used to support the cables across to the right socket, with cable ties being used to secure cables. Don't forget to keep mains power and lower level signals on opposite sides of the rack to minimise interference. [caption id="attachment_915" align="aligncenter" width="600"] Where to start fault-finding in a mess like this?[/caption] In my experience, a tidy rack with neatly-secured cabling is much less likely to have faults, but even in the event of a fault, finding it in a tidy rack is far easier! [caption id="attachment_917" align="aligncenter" width="300"] A well-dressed rack makes fault finding easy. (Image courtesy of Konnectiv Technology).[/caption] Conclusion Designing, installing and commissioning a rack full of equipment can be a daunting task. There is much to think about and a world of choice when it comes to components. However, a properly-installed system within a professionally-wired rack looks better, will be easier to service and leaves the customer with a real sense of a professional installation. If you've never used a fully-fledged rack in an install, check with your local rack supplier, training provider or CEDIA, to see which courses they run that can train you in how to properly specify, populate and dress a rack. Geoff Meads is a consultant to CEDIA and Managing Director of Presto Audio Visual Ltd, a Web design and technical training agency specialising in the residential technology sector. www.prestoav.com

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