Last updated: August 15, 2021

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Any well-versed sound professional can tell you about the benefits of bulbs in audio systems, how they enhance the sound, amplify it and give it a very distinctive and desirable tone, which is why they are still a sought-after technology despite the years.

Choosing bulbs can be a bit confusing, because although everyone talks about how good they are, few tell you how to start using them, so whether you are buying bulbs to repair an electronic system, or to give a personal touch to your guitar amp, in this guide you will learn how to buy the best bulbs on the market.

To make this guide, we researched the most sought-after features of bulbs, paid close attention to reviews of the most popular models, and then researched where you can buy them and the price you can expect to pay for them.




The Most Important Facts

  • Bulbs are electronic components that are part of various electrical devices, whose role is to amplify and modify electrical signals. Today they are part of high-end sound systems, such as audio equipment and amplifiers for various musical instruments.
  • There are a multitude of bulb models and they all play the same role of amplifying and modifying signals, but they differ in their sizes and design. There is no one bulb model that is better than another, as they all provide characteristic sounds that may or may not appeal to different listeners.
  • If you are buying a bulb for use in a sound system, it is recommended that you watch videos of people using the model you are interested in to see if you will like the sound of the bulb or not. If you are buying a bulb to replace a damaged bulb in equipment whose purpose is not audio playback, try to buy one that is known to be durable.

The Best Bulb: Our Picks

Buying Guide: What you need to know about Bulbs

In this section we will help you to find out what bulbs are used for, what the different bulb models are and the prices at which they can be found. All this information will help you to make a better buying decision when you want to go shopping for new bulbs.

No two bulb models sound exactly the same, even among similar models of the same brand. (Photo: Liu Fuyu / 123rf.com)

What is a bulb and what are its advantages?

A bulb, also called a vacuum tube or vacuum valve, is a device used to modify the flow of electrical current in various electronic devices. They were an important component of electronic systems from their inception in the early 20th century, until their eventual disuse due to the advent of transistors.

They have had a resurgence in high-end audio systems due to the auditory contribution they provide, especially in those used in theatrical sound systems, also in guitar and bass amplifiers, as their tones are considered superior to those produced by transistors and consequently more pleasing to the human ear.

Advantages
  • Pleasant tones
  • Clear sound
  • Short protection
  • Good sound at low volume
Disadvantages
  • Variable lifetime
  • Overheats
  • Expensive
  • Uses a lot of energy

Bulbs type 12AX7, 6L6, 6V6, EL34, EL84- What should you pay attention to?

The number of bulb types on the market is really high, which can be intimidating if you don't know which one is right for you. In this section we will explain briefly about the most commonly used bulbs in audio systems, especially those used in bass and guitar amplifiers.

It should be noted that if you are replacing a bulb it is preferable that you do it with the same model, otherwise you could end up with an incompatible bulb or one that damages your equipment. For this we recommend consulting a professional, as they will be able to tell you which bulbs your equipment needs and install them safely.

Bulb 12AX7

Also called ECC83, this is a bulb that is often used in the pre-amp section of amplifiers, so it is often referred to as a pre-amp tube. It is one of the most widely used bulbs on the market, so there are a lot of variations of models and companies that manufacture it.

6L6 Bulb

This is a large bulb used to power the great classic American designed amplifiers of decades past. It is well known for maintaining clean sounds of modest mid tones and bass with presence. It has been part of successful guitar amps since the 1950s.

6V6 Bulb

Known as the "little brother of the 6L6". It is another bulb that has a presence in American style amps, as it has a very balanced sound. It is very sought after because it achieves distorted sounds very characteristic of heavy rock.

EL34

This is the star bulb of British rock, as it has been part of amps used by artists who started the British rock scene. It is loved by guitarists because of its slightly dirty, mid-heavy sound that becomes crunchy when distorted, which any guitarist who is a fan of classic European bands will love.

EL84

The EL84 is to the EL34 what the 6V6 is to the 6L6. It is a similar bulb to the EL34 but with smaller dimensions. It is known for its bright high tone which like the EL34 becomes crunchy when overloaded. Due to its higher gain it tends to return a dirty tone when used with an electric guitar.

12AX7 6L6 6V6 EL34 EL84
Feature Highlight Highly manufactured Clean sound Easy overdrive Strong midrange sound Warm sound
Main use Most used preamp bulb Large American style amps Small American style amps British style amps British style amps

Bulbs are widely used because they provide a unique and powerful sound. (Photo: Zvonko Djuric / 123rf.com)

Buying Criteria

Buying bulbs can be very tricky if you have never bought bulbs before, because at first glance all bulb models look similar. To help you buy bulbs we have put together the most important factors that should influence your purchase, so you can go out and buy bulbs that live up to your expectations.

Requirements of your sound system

Before buying a new set of bulbs you should know the requirements of the equipment you are going to install them in. If you buy a different model of bulb than your sound system requires, you could end up with an unusable bulb or worse, damage your electronic equipment.

Many guitar amplifiers and Hi-Fi sound systems have bulb sections for use as amplifiers or preamplifiers, and these have bulb requirements that can make a difference to both tone and volume.

Amplifier bulbs

These are the ones that take the signal from the source to increase the final volume. You can control them using the volume knob on your bulb sound system, or on your guitar amp. They influence the feel of the sound more than the tone of the sound.

If your sound system uses 6L6 bulbs in its bulb amp section, it is preferable to buy only 6L6 bulbs or bulbs of a very similar design, such as the KT88. If you try to fit a very different bulb model, for example, an EL84, it will most likely not even fit in the bulb socket of your system.

What you can do is to replace a bulb model with a similar one manufactured by a different company, which curiously can lead to tone changes, as each company has a different manufacturing process that ends up influencing the final tone generated by each bulb.

Preamp bulbs

These are slightly smaller than the amplifier bulbs, and are used to pick up the signal from the source to amplify it before it is sent to the amplifier bulbs. Arguably, they are responsible for the distortion effects in guitar bulb amps and pedals.

If your amp has a preamp bulb section, you can combine preamp bulbs of different models. If, for example, you have an amp that uses 2 12AX7 preamp bulbs and one is damaged, you can replace the damaged one with a 12AT7. This will influence the resulting sound.

Durability

It is difficult to quantify the lifespan of a bulb, as this not only varies from model to model, but also by the equipment in which they are used. For example, an EL34 bulb has an average life of 2500 hours of use, but if they are used in less demanding amplifiers and sound systems they will last longer.

The best way to know if your bulbs are nearing the end of their life is to get new or lightly used bulbs and replace the old ones. If you notice any drastic change in sound quality it is time to replace them, if you don't, return the old bulbs to their original position.

This is because over time the efficiency with which the bulbs work tends to diminish, which means that both their sound output and their tones are gradually lost. So if you're a guitar player who relies heavily on your vacuum bulb amp, you'd better keep spares on hand.

Overdrive

When a bulb is said to have good overdrive, it means that it is capable of achieving a distorted sound that is pleasing to the human ear, which happens due to an over-amplification that occurs in the output current.

There are bass and guitar amps and pedals that use vacuum tubes to achieve this.
For example, when a guitarist turns up the volume on his tube amp, the signal is distorted, causing him to reproduce audio with a tone that is very characteristic of rock and blues bands. This is why the 12AX7, EL34, El38, 6L6 and 6V6 bulbs are so successful, because they allow for decent clean sounds and overdrive.

Noise

Some bulbs are capable of picking up external sounds in the same way that microphones do, so if you are using a set of bulbs in your sound system, make sure they are not microphonic, otherwise they will negatively affect the audio quality of your sound system.

(Featured image photo: chva / 123rf.com)

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