Most preamps aren’t cheap, so you don’t want to ruin your investment. But what if your preamp is hot. Should a preamp even get hot, and when is it too hot?
A preamp will get warm, but it’s too hot when you cannot leave your hand on the top. This excess heat could be caused by dust, a broken fan, or incorrect placement of the preamp. Creating more space around the preamp or using a small fan to provide adequate cooling are two ways to cool it down.
A preamp can put out a lot of heat for a piece of equipment without moving parts. If you’re worried about your preamp, this guide will help you understand why they get hot and then give you tips on how you can cool yours down.
Why Do Preamps Get Hot?
Preamps and other electronic equipment with transistors get hot because of the current that flows through them. An electric current heats up because the electrons moving through the current bump up against each other, thus creating heat through kinetic energy, a process called Joule heating.
Electronic designers add several components to cool a preamp, including heat sinks which remove the heat by transferring it from the transistor into the air. Heat sinks are large pieces of metal designed in such a way as to allow maximum surface area. They wick the heat away from the chip or transistor, transferring it to the heat sink, allowing more efficient heat dissipation.
When Is a Preamp Too Hot?
A preamp is too hot when you can’t leave your hand on the top. This excessive heat could be caused by dust, a broken fan, malfunction, or incorrect placement of the preamp. Creating more space around the preamp or using a small fan to provide adequate cooling are two ways to cool it down.
What Happens When a Preamp Becomes Too Hot?
When a preamp becomes too hot, the excessive heat can damage it, just like all electronics such as computers. Luckily, most preamps sold these days come with shut-down features when they overheat.
If your preamp doesn’t dissipate heat effectively, the life of output transistors will also be shortened, and you’ll eventually hear increased distortion.
How Can You Cool Down a Preamp?
Start the troubleshooting process by first checking on what can be most easily remedied—air circulation. If that’s not the issue, then there are a few additional solutions to consider.
Fix Inadequate Air Circulation
The most common reason that preamps get too hot is location. A preamp shouldn’t be located too close to heating ducts or other heat-producing equipment. Hopefully, you haven’t placed your gear in an area where it gets direct sunlight. But if you’ve done so and put them in a cabinet, thinking to protect the equipment from heat, you could actually be trapping heat in the cabinet.
You cannot always go by the manufacturer’s guidelines regarding spacing. Guidelines can be anywhere from 2 to 4 in (5.08 to 10.16 cm), and some manuals will simply say you need to provide enough space for air to circulate.
Their guidelines are often vague because they cannot control each variable that would go into location and heat. Instead, they assume that a person who invests in a preamp will notice when it’s too hot and make adjustments that will allow the equipment to run cooler.
One adjustment to make is if you’re stacking equipment, unstack them. You’ll not get adequate airflow between them, and the heat from the component below (probably your amplifier) will rise.
Ideally, each component of your system should have its own shelf, so this might be time to invest in a shelving unit that has separate shelves.
Cool the Preamp With a Fan
A preamp can be cooled with a small fan, which is a popular option for many audiophiles. Here are some fans you can choose from that are available on Amazon.com:
- Separate small fans. Buy small and inexpensive fans, such as the Arctic Breeze Mobile Desktop Fan, a small USB-powered fan that usually runs under 10 dollars. It’s quiet and has a flexible neck.
- Small USB computer fans. This set of Xin Da Yuan USB Computer Fans are intended for computer and AV cabinet cooling. Unlike some small fans, these come with rubber foot pads to make them quieter. You can also find similar fans at stores that sell computer parts.
- Fans with temperature control. These fans let you adjust the speed and solve the problem of noisy fans affecting your listening pleasure, but they come at a higher price. An example are these AV Cabinet Cooling Fans which have speed control and thermal switch that turns the fan on when temperatures rise above a preset temperature. They sit on top of an electronic component and pull air out.
- Cooling kits for cabinets. If the idea of having holes drilled in the sides of your cabinet turns you off, cooling kits include fans set into small grills. This Coolerguys CabCool Fan includes a thermal control switch and an oak grill. The fans can be reversed—have one bring air in and the other pull air out.
You also need to think through fan placement. As we know, warm air rises. If your fan blows down on your equipment, it’ll trap the hot air exactly where you don’t want it to remain. Fans should push cool air over the equipment in an open cabinet, meaning you want to place them on the side of your preamp and have them blow cool air over it.
Some people suggest that you point the fans outward to pull the warm air out. Although that method will work to extract hot air, it won’t cool the amp. To create a draft, compromise. Point one fan to bring in cool air and place a second fan on the other side to pull out the hot air so that the air is pulled out of the area.
If you decide you don’t want to cut holes in the sides of your cabinet, then consider having one fan on the bottom of the cabinet pointing up and an exit point near the top of the cabinet, so the hot air has no choice but to move up.
So it’s crucial to pay attention to the airflow path. Hot air rises, so place your fans, so you work with that principle, not against it—no sense in working harder than you need to.
Why Not Just Get Rid of the Preamp?
A preamp’s job is to take an audio signal from a source and add character and warmth shape and definition before it’s amplified for additional processing through the amplifier. Preamps add character and warmth to your sound, whether you’re using them for recording or playback.
In a Hi-Fi setup, you can’t just get rid of the preamp unless you have an integrated amplifier (amp and preamp in the same box) to use instead.
A preamp gets hot, but it shouldn’t get too hot. Generally, if you can’t keep a hand on it, then it’s definitely too hot.
Designers and manufacturers aren’t specific in manuals regarding how hot is too hot. It’s not because they don’t want to tell you, but environmental factors play a role, and they cannot know what they are.
One guideline is that most small fans with temperature controls turn around when the temperature is in the mid-80s inside a cabinet. Remember to provide adequate room around your preamp (and all electronic equipment) and keep it out of direct sunlight.