Where to put your amplifier Heat, ventilation and space on the cabinet: why your amplifier needs air around it
The amplifier is the part of the system that gets hottest. On the cabinet it needs air, and the rule I give everyone is just one: never anything on top.
Why it gets hot.
An amplifier takes power from the mains and turns it into the energy that drives the speakers. Part of that energy becomes heat. To get rid of it there are heat sinks, the metal fins you can often glimpse through the grilles, and the vents in the lid through which the hot air escapes. In some models the whole chassis acts as a heat sink, which is why the lid gets hot to the touch.
How hot it gets depends on how it's built. Class A amplifiers are the hottest, because they draw a lot of power even when playing quietly; class D amplifiers, the most efficient, get much less hot. But all of them need to let the heat out.
Never anything on top.
It's the rule I give everyone. An object resting on the amplifier, whether a book, another component or the turntable, blocks the vents the hot air escapes through. The heat stays inside and the unit runs hotter than it was designed to.
This isn't just a woodworker's habit: manufacturers write it in their manuals. Rega advises against stacking other equipment directly on top of the amplifier. Arcam and JBL ask you not to place objects or other electronics on it. Rotel asks you not to block the ventilation slots.
A turntable on top of the amplifier is doubly wrong: besides blocking the air, the amplifier's transformer can make the cartridge hum. In the Brio manual, Rega advises keeping the amplifier as far from the cartridge as the tonearm lead allows.
How much space to leave.
The manuals give similar figures: Rega and Rotel call for at least 10 centimetres of free space around the unit, Audio Analogue at least 5 centimetres around and above. If your amplifier's manual gives a figure, follow it; if you can't find one, 10 centimetres of free space above is a good reference.
On the cabinet, that means choosing a shelf at least that many centimetres taller than the amplifier, and leaving space behind it too, where cables and plugs come out.
My furniture. In the Vinyl the amplifier shelf has 28.4 centimetres of clear height in the Beech version, more than most amplifiers need: air stays free above it. In my other hi-fi racks each component has its own shelf.
Neither on top of nor under another component.
The advice works the other way too: better not to put the amplifier on top of another component. Heat from the one below rises and warms the amplifier, and two units close together can interfere with each other: Rotel, for example, advises against placing the amplifier on other equipment precisely to avoid interference. Ideally, each component has its own shelf.
Closed cabinets and soft surfaces.
An amplifier shut in a compartment with no air exchange heats the air around it and keeps heating the same air. If the cabinet has doors or a closed back, leave space around the unit and an opening at the back. Rotel says so clearly: if the unit sits in a bookcase or cabinet, there must be enough space around it for ventilation.
Don't place it on rugs, sofas or fabric, which block the openings underneath, and keep it away from radiators and heaters.
Why it pays off.
Heat is electronics' main enemy. Electrolytic capacitors, among the first components to age, last roughly twice as long for every 10 degrees cooler, according to their manufacturers. An amplifier that can breathe runs cooler and lasts longer.
Many amplifiers also have a protection circuit that switches them off when they overheat. If yours shuts down by itself after playing loud for a while, the first thing to check is the air around it.
Amplifiers on ExtrasoundOn Extrasound, the hi-fi shop that sells my furniture, you'll find amplifiers and furniture with a shelf for each component.
Frequently asked questions.
Can anything be placed on top of the amplifier?
No: you'd block the vents the hot air escapes through. Manufacturers advise against it in their manuals too.
How much space does an amplifier need above it?
Follow your model's manual. Many manufacturers call for at least 10 cm of free space around the unit.
Can the turntable go on top of the amplifier?
No: it blocks the air and the amplifier's transformer can make the cartridge hum. Better two separate shelves.
Can an amplifier go in a closed cabinet?
Only if there's space around it and air can circulate, for example with an open back. In a closed compartment the heat builds up.
Is it normal for an amplifier to get hot?
Yes: some use the whole chassis as a heat sink and get hot to the touch. But if it switches itself off, it needs more air.