THE Audinni BLOG

AV Furniture: Design, Making & Maintenance.A blog from Audinni MD and third generation cabinet-maker Simon Gavin, featuring informative posts about the world of AV furniture, including numerous expert tips, a buying guide to AV cabinets, Hi-fi stands and other performance AV furniture.

The AV Cabinet Buying Guide, Part One: Ventilation.

 av cabinet ventilation open back active cooling fans Audinni
The rear of a bespoke Audinni Profile AV Cabinet showing an open-back, and slotted base, with active cooling fans for closed areas [client specification.]
"Nothing in life is certain except deathtaxes and the second law of thermodynamics." 
- Seth Lloyd, Professor of Mechanical Engineering at MIT, 2004.
"In this house, we obey the laws of thermodynamics!"
- Homer J Simpson

The Audinni AV Cabinet Buying Guide is an occasional series of articles detailing the various technical and aesthetic issues to consider when buying an AV cabinet. Part One deals with ventilation and heat control.

Ventilation and heat dispersal should be one of the main considerations when buying an AV cabinet. AV equipment produces a lot of heat. If this heat is not dissipated effectively, then it will have an adverse effect on both the performance and the lifespan of the equipment.

** Several studies have established a maximum operating environment ´╗┐temperature of 30 degrees Celsius [85F] for AV seperates. For every 5 degrees of temperature in excess of 30C, equipment lifespan can decrease by a staggering 40%. A further study from the Uptime Institute states that for every 10 degree rise over 21 C, long term performance reliability is reduced by 50%.**

The actual amount of heat produced by your equipment will depend upon the amount of power drawn by the equipment in the first place. Although the "conservation of energy" principle means that the amount of heat emitted by a piece of AV equipment cannot exceed the amount of power it uses, some Class A AV amps can transfer up to 80% of the input energy into heat output. [Class D amps are far more efficient, and can be as low as 15-20%. Manufacturers are being increasingly pro-active in publishing heat output data.]

Correct AV cabinet design can solve the problems of heat build-up. Bad AV cabinet design can actually make things worse!

There are essentially two main solutions:

- Passive convection [enabling heat transfer and dissipation through airflow].

- Active cooling [fans, heat exchangers, air conditioning, etc.] 

When designing a Audinni AV cabinet, thermal management via passive convection is one of our key performance considerations. [We have specified 'active cooling' fans in a number of cabinets, but this is normally where a client has requested an aesthetic appearance that prohibits passive airflow.]

The over-riding principle is to create a clear exit-route for heat to follow. Using this principle of passive airflow as a design fundamental, we normally specify an "open back" exit route for heat. Further ventilation is provided through air inlets in the floor of the cabinet. Wood slotted-shelves assist with sub-unit ventilation, however it is important to avoid re-circulation of hot air, or short-circuiting heat from one component to another. Depending upon requirements, we may specify slots in the rear top of the cabinet.

A performance AV cabinet should have a clear airflow built into the design. For example, in tall cabinets with multiple separates,  it is necessary to establish a "chimney effect" for rising heat, at both the sides and to the rear of the cabinet, with heat able to escape at the top of the cabinet.

All of our standard AV cabinets have been designed with passive airflow in mind. [Naturally passive airflow will also depend upon the ambient temperature of the room/environment, but this would normally be lower than the heat produced by the AV equipment.] When designing a bespoke AV cabinet, we will discuss yourequipment with you and having understood your heat dissipation requirements, we would design a piece of furniture with appropriate airflow channels and exits. 


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