Media console and equipment rack dimensions

The depth nobody measures#

Cabinet depth is quoted externally and equipment depth is quoted without its plugs, and the difference between those two conventions is where most media furniture fails. An AV receiver in a catalogue is 17 in (43 cm) deep. The same receiver in a cabinet is 21 in (53 cm) deep, because an HDMI plug body projects about 0.9 in (23 mm), a stiff high-bandwidth cable needs a bend radius near 2 in (50 mm) before it will turn down, and an IEC power lead wants the same again.

Set the datum at the inside face of the back panel. Everything is measured forward from there.

The last two rows never meet. A cabinet built to 24 in (61 cm) external solves it at a stroke, and that is not a coincidence: 24 in is the standard base cabinet depth, which is why media walls put together from built-in cabinetry work when furniture bought as furniture does not. The alternative is an open back and a cabinet standing 3 to 4 in (75 to 100 mm) off the wall, which then has to be reconciled with the skirting.

Console height, derived from the screen#

The console top is not a free choice. It is whatever puts the screen centre at the seated eye line, which for a sofa is around 42 in (107 cm) and is worked out properly in eye level and sightlines and in TV size, distance and mounting height.

For any 16:9 panel, height is 0.49 times the diagonal and width is 0.87 times it. So the console top has to sit at 42 in minus half the panel height minus about 2 in (50 mm) of pedestal.

Consoles are sold at 24 to 30 in (61 to 76 cm) tall. Read the fourth column again and the consequence is unavoidable: anything above 65 in of diagonal cannot stand on a normal console and keep its centre at eye height. At 75 in the console has to come down to 21.6 in, at 85 in to 19.2 in, and by 98 in it is a 16 in plinth, which is below seat height and looks like one.

That is the arithmetic behind the shift to wall mounting, not fashion. If the screen goes on the wall, the console becomes a low plinth of 16 to 20 in (41 to 51 cm) and its only job is depth and ventilation, with the mount taking over the height problem and its own constraints set out in TV wall mount dimensions, VESA and stud spacing.

Width has a simpler rule. Our recommendation is the screen width plus 6 in (15 cm) at each side, which for a 65 in screen means 68 to 72 in (173 to 183 cm). Narrower and the screen visibly overhangs. Much wider and the console starts to read as a sideboard with a television parked on it. The full range of stocked sizes is in TV stand and media console sizes.

In a projection room the rule inverts: the console has to finish below the bottom of the screen with clearance for the acoustic centre of the centre channel, and that bottom edge is fixed by the throw geometry in projector throw distance and screen size.

Rack units and the 19 in module#

Rack-mounted equipment follows EIA-310, which fixes the panel width at 19 in (482.6 mm) and the vertical module at one rack unit, 1.75 in (44.45 mm). The mounting flanges are 18.312 in (465 mm) apart and each unit carries three holes spaced 0.5, 0.625 and 0.625 in, which is why a panel bridging two units sometimes will not line up if it was punched to a different convention.

A four-post frame measures about 20.25 in (514 mm) across the uprights. A 600 mm joinery carcass with 18 mm sides has 564 mm of clear internal width, so the rack fits with 25 mm each side and no room for a vertical cable duct. That is another instance of the imperial and metric collision that runs through every fitted installation.

Vertically, the arithmetic decides how tall the cabinet has to be.

That totals 22U, or 38.5 in (98 cm) of panel space before the plinth and the top cap. A 12U rack, the size most people buy, gives 21 in (53 cm) and holds about half a system. Add a 4 in (100 mm) base and a 2 in (50 mm) top and the cabinet finishes near 45 in (114 cm) tall, which is deeper into the room than a console and usually ends up in a cupboard next door. Getting the signal there is a cabling question covered in data and network outlet placement.

Heat, and the airflow that removes it#

The relationship is fixed: the airflow needed to carry heat away is CFM = 3.16 x watts / temperature rise in degrees F. A receiver, a disc player and a streamer together dissipate roughly 200 W at ordinary listening levels. Holding that to a 10 degree F (5.5 degree C) rise needs 63 CFM through the cabinet. Accept a 20 degree F rise and it halves to 32 CFM.

Natural convection through a grille runs at 50 to 100 ft per minute of face velocity, so 32 CFM needs something like 45 sq in (290 cm2) of free area at the bottom and the same at the top. Decorative grilles are 40 to 60 per cent open, so that is two grilles of about 90 sq in each, roughly 6 x 15 in (150 x 380 mm). Most cabinet doors have a 20 sq in slot and a hopeful attitude.

Our working limit is that a closed cabinet with generous top and bottom vents handles about 75 W. Above that, fit a thermostatically switched fan, which moves 25 to 100 CFM from a 120 mm unit and costs less than a repair. Manufacturers typically ask for 4 in (100 mm) above a receiver and 2 in (50 mm) at the sides and rear, and those figures assume the cabinet itself is ventilated. The same logic and the same formula govern the service space in HVAC and air handler clearances.

Cables, conduit and the depth behind#

Behind the console, allow 4 in (100 mm) with the back panel cut out and 6 in (150 mm) if the back is solid and the cable has to turn twice. Behind a wall-mounted screen, the depth budget belongs to the mount, and the outlet has to be recessed so the plug does not add to it, with heights and box depths given in TV outlet, cable and conduit heights.

Conduit sizing is a plug problem rather than a cable problem. An HDMI Type A moulded body is roughly 0.9 x 0.6 in (23 x 15 mm), so 1.5 in (38 mm) internal diameter takes one terminated cable comfortably and 2 in (50 mm) takes two. Never size the conduit to the cable diameter: the connector is three times thicker, and a fitted plug will not pass a 1 in tube however hard it is pushed.

Leave a draw cord in every run. It costs nothing during the build and it is the difference between a five minute upgrade and a plasterboard repair.