Secrets of Home Theater and High Fidelity - John E. Johnson, Jr.

Heat is the main enemy of consumer electronics. Unfortunately, many amplifiers get hot during use, especially if they have any bias into Class A operation.

I have several amplifiers that get quite hot – too hot to leave my hand on the heat sink fins for more than a few seconds.

One in particular – a Classé CA-5200 – has another issue. It is on a shelf where the top of the chassis is only a few inches from the bottom of the next shelf up.

This presents a heat dissipation issue, and this amp gets hot.

Little Things: Keeping your Cool with Hot Amplifiers

So, I purchased a product called the Vornado Zippi, which is a small fan that has cloth blades.

The fan is mounted on a stand that is very flexible to allow the fan to be pointed at any angle you wish.

The Vornado Zippi fan is available for $29.95/each from Westside Wholesale.

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I purchased several of these fans and put two of them near my Classé CA-5200 multi-channel power amplifier as shown in the photos below. One cools the left bank of heat sink fins, and one cools the right bank.

Little Things: Keeping your Cool with Hot Amplifiers

Little Things: Keeping your Cool with Hot Amplifiers

The fans are about 2/3 of the way back and point up at about 45 degrees, towards the heat sink fins. I can feel the air coming out across the top of the amplifier.

I turn them on by connecting them to a power strip. This lets me turn both on with just one power button.

I measured the temperature of the heat sinks when the amplifier was off. It was 77 degrees. I turned it on, and after an hour, the heat sinks were 114 degrees. Then I turned on the fans. After 5 minutes, the temperature had decreased to 99 degrees, and after 30 minutes, it was 89 degrees, where it stabilized. That is a 25 degree reduction in temperature. These measurements were made with no music playing, so the amplifier was at “idle”.

Note that transistors are designed to operate within a range of temperatures (SOA Safe Operating Area). With the fans, they will be operating in the lower part of the range, and the amplifier will last longer. Also, I used these fans because the amp was sitting too close to the shelf above it. For amps sitting in a large space, the fans would not be necessary. However, being paranoid, I would use them anyway. Here is a quote from Elliot Sound Products: “Under ideal conditions, a transistor’s power dissipation rating refers to the maximum peak power that the device can handle, with the junction temperature at 25° C. At any temperature above 25°, the power is derated (reduced) linearly, until it reaches zero at around 150° C. In some datasheets, you will see that they refer to case temperature, rather than junction temperature. Regardless to the terminology used, it is the maximum permissible temperature of the silicon die (the semiconductor junctions) that is the limiting factor. Very few transistors are designed to operate with a junction temperature above 150°C.”

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One nice feature is the soft cloth blades. You can stick your fingers in the blades and not get cut. It doesn’t feel good, but in case you have small children with curious fingers, they will probably just have a good cry but no cuts. I also found my cats think they are an interesting item to poke their paws into. They keep doing it, so it seems harmless enough.