Why Do Tube Amps Sound Warmer?

There are different types of noise in audio production and audiophiles pride themselves in dealing with noise as surgically as possible.

For example harmonic Distortion( usually called warmth) produced by tube amps is one of the more preffered types of Distortion.

Most people reading this may think that noise is something to be completely avoided but the fact is tube amplifiers produce noise that is a key important characteristic of the final signal they amplify.

This article will discuss why tube amplifiers sound warmer because it is a question I often times come across in most audio production forums.

With that said, why do tube amps sound warmer?

Tube amps have two types of tubes, Pre-amp tubes and Power Tubes. Audio signals hit the pre-amp tubes first which makes the signal accumulate character, warmth and some distortion, and then the power tubes amplify the resulting signal. Tube amps sound warm because signals run through them accumulate slight distortion which is then amplified.

Warmth in audio production is usually what you get when you add saturator or run an audio signal through a saturator. It adds harmonic distortion just like a tube amp does.

Which is why most people say that tube amps make sounds warmer because of the pleasant distortion they add.

Below are some more reasons why Tube amps sound warm.

Lack of Inverters

Tube amplifiers don’t need Inverters for them to amplify sound which makes them produce more cleaner and warmer signals because there are fewer components to interfere with any amplification processes.

Tube amplifiers also store and regulate their own power so they don’t need any external AC or DC source of power which can alter the resulting signal.

A signal free of interference will have high fidelity, will sound clearer and warmer.

No Background Noise

Unlike other equipment that you may want to run your audio signal through. Tube Amplifiers sound extremely clean even when you’re playing at a low volume.

In other words, tube amplifiers have less background noise and hiss so you wont encounter any annoying hiss or interference like I’ve discussed in the previous point.

The ability of tube amps to amplify signals while preserving their original state to a high degree makes them produce warmer sound only coloured with slight harmonic distortion.

Which leads me to my next point.

Distortion

Tube amps like we’ve discussed add some distortion and drive amplification while preserving the signal.

But you’ll notice that tube amps add distortion moderately when the signal is being played at low volume.

When you crank the volume up, the amplifiers start to clip and the distortion may be more noticeable.

This is one of the reasons why Tube amplifiers warm sounds.

Volume and clipping

In relation to the previous point…you can easily tell that there’s a relationship between volume and clipping in tube amplifiers.

Most audiophiles will tell you that perhaps one of the reasons why a tube amplifier might sound warmer when compared to another type of amplifier is because of its volume control feature.

When the volume control is cranked up, the tube will automatically start to clip especially when you reach the limit of what their circuitry is able to allow.

This effect produces distortion and makes the resulting signal warmer.

Silence

There are no speakers inside an amplifier so it won’t make any noise and will be silent when there’s no signal being run through it.

Compared to vacuum tubes…tubes are cleaner and you won’t have to worry about any background noises.

The signal you run through your tube will retain its integrity while sounding warm.

Sound Wavelength

Tube amplifiers produce much softer sounds because when the sound waves are run through them..they tend to to slower with less energy …creating more pleasant resulting sounds.

Other ways to add Warmth to sound

Of course tube amps are important but what would one do if they didn’t have access to one but still wanted to amplify their sounds…?

Below are some alternative ways you can use to add some warmth to your audio signals.

Saturation

One of the best ways to achieve or add some warmth to a signal is through the use of a saturator.

Saturators like tape machines can be a good way to achieve some warmth.

You can also use digital plugins like Fab Filter Saturn which is a great saturator that I like to use.

Parallel Compression

Another great way to beef up audio like vocals is by using parallel Compression.

Parallel Compression is the act of doubling vocals… which is why vocals sound meaty and warm after it is applied.

Of course this takes some practice to find the best possible way of carrying out this practice. 

Ambience

Addiing Ambience to sounds using tools like reverb and other ambiance plugins is a great way to add some space, width and ambiance to sounds. I like to use RC 20 Retro Color.

It is an effective and easy to use tool.

Conclusion

Tube pre-amps are able to add Warmth to sounds by boosting the low end while also driving the highs… all this is done moderately to ensure that the resulting signal is not too harsh.

This is one of the reasons why it’s very difficult to reproduce the warmth from tube amplifiers with digital plugins.

Because you can’t reproduce the sound of a tube amplifier without physical tubes.