A while back, I had the opportunity to jam with the guitar legend, Carlos Santana, on his “Shaman” album.
I remember being in the live room the day before, ensuring all his solid-state, tube, and power amps were good to go. Just as I was about to turn off the lights and the equipment, the engineer stopped me in my tracks.
He asked, “What are you doing?”, and I told him I thought we were wrapping up. That’s when he revealed – Carlos likes to leave his amps on all night to achieve that perfect distortion. The man prefers his sound hot, literally.
That session was an eye-opener for me about amps. They heat up for various reasons. For Carlos, it’s all about the sound.
However, sometimes, it could indicate a problem. So, let’s discuss four reasons why Amps can get hot and the red flags to watch out for if they’re generating too much heat.
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4 Reasons Amplifiers Get Hot
One of the main reasons many amps get extremely hot is due to vacuum tubes. This isn’t exclusive to guitar amps; many high-quality preamps and speaker amps with added tube circuits also heat up to provide extra warmth.
The term ‘warmth’ is often used to describe second and third-order harmonics in music. The two primary providers of this warmth are vacuum tubes and tape.
If you’ve ever opened a piece of music equipment, like an amp, preamp, or compressor that uses vacuum tubes, you’ll notice that they glow similar to light bulbs. This is because they’re designed to control the flow of electric current.
My advice for using any tube amp is to turn it on and let it warm up for at least three hours before use, and then leave it on for the next 12 hours. Most well-constructed tube amps control the amount of collateral heating, which includes other components near the tube, such as the grill and casing.
So, don’t worry if your amp gets extremely hot; it’s actually a good sign.
However, if you start smelling something unusual, it could be a sign of an issue with poorly constructed circuit boards that may be melting due to the heat of the tube. This could be problematic, and I recommend always trying to buy the highest-grade tube gear possible to avoid such issues.
Power and Voltage Problems
Shortly after my arrival in LA, I designed a few studios for notable producers to earn some extra money. While studying at Berklee, I learned about acoustics and the optimal placement of equipment, but I hadn’t delved much into the wiring aspect of studio construction.
While planning out the best location for the studio within a house and implementing well-grounded power, I learned a lot. Having never wired a studio from scratch before, I didn’t realize how much power output and current could impact the performance of the gear.
If you’re noticing unusual changes in your amp’s performance, such as overheating, you should check the grounding of your dwelling. This applies whether you’re in a recording studio, house, or apartment. It’s crucial to have proper solid copper wiring grounded with a copper rod.
If this is too complex or if you’re a renter without access to the wiring, the best workaround is to use a Furman power distribution strip. Despite having well-grounded copper wiring throughout my studio, I still use Furman power conditioners with all my amplifiers, especially the tube gear.
If you’re running multiple guitar amps in a live room, I also recommend the Black Lion Audio PG-XLM power conditioner. It features a handy voltage monitor on the front that allows you to track any variations in power distribution from your main outlets.
With regulated power, your amplifiers won’t have to work as hard to control the Bias when idling. I’ll discuss this more in the next section.
Bias is a significant factor that heats up your amp. However, it’s not a big issue when you’re actively using it, but rather when the amp is idle.
Bias is a setting on your amp that manages how much DC current or outlet power your amp uses when it’s not in use.
It’s crucial to understand how your equipment handles being left on for many hours. Many people are unaware of Bias and how to adjust it for optimal results.
Most amps have a feature called a Bias trimming pot on the PCB (Printed Circuit Board). It’s typically set to the factory default settings upon purchase.
However, some tech-savvy users like to adjust these settings to make the voltage run a bit hotter in the amp. This adjustment makes the tubes work harder and produces a richer distortion.
Overheating is typically a more significant issue for tube amplifiers than solid-state amps, but solid-state amps can also overheat if the DC voltage isn’t correct. This issue can affect the sound, altering the frequency response and volume.
It can also make your amp noisier when it’s struggling with the incorrect current while idle. It’s essential to monitor your amp to ensure it’s not overheating to the point of blowing a fuse or causing more severe damage.
How hot is too hot for an amp? It’s somewhat subjective. Some people are okay as long as the amp isn’t actually on fire. But in my experience, standalone amps should not be so hot that you immediately pull your hand away.
If you’re using a high-level amp device, like for speakers or to enhance the sound within a rack with other equipment, I wouldn’t let it get hotter than a temperature that you could leave your hand on it for 10 seconds without pulling away.
A common reason why amplifiers get hot is usually because they’re not getting enough air. Many of my top-tier amps, which are meant to go on a rack or stand-alone, have this cool mesh grill for air to pass through.
The heat from all that tech and the tubes inside just rises right out, mostly from the top. You’ll see this a lot in Manley and other similar tube gear brands. I also leave one unit in the rack space above it empty to ensure good ventilation.
Audiophile stand-alone tube amps like the McIntosh series are meant to display the huge amount of vacuum tubes out in the open. I’ve been to a few vinyl bars and homes where they have these McIntosh tube amps on display, all lit up and super cool looking.
Guitar amps are built with ventilation in mind. So if I’m recording in a small room or closet, I’ll use a slow fan to keep the heat off the back of the amp. I turn it off when I’m recording, but any extra cooling is a good thing for amps.
Another thing to remember is not to put amps against a wall when they’re on. Some sound engineers and producers try to reduce room echo in their sound and try to isolate amps. But you don’t want to do this with a wall or anything else that could block the air from getting out of the back of the amp.
Your amp getting hot can be both a blessing and a curse. Sure, it can enhance the sound, but it can also damage your amp’s internals.
Understanding your amp and finding its sweet spot is crucial. Different brands and styles require different warm-up times to achieve their best sound, but once you’ve mastered it, you’ll know when to let them cool down.
Generally, if you don’t see any signs of heat damage, such as melting parts or worn-out components on the circuit board, you’re usually safe to leave your amp on for most of the day, provided you have a steady power supply.