Deal with interference in the audio signal

Combattre le bruit parasite en studio ou sur scène

In the electric violin, as in any electrical or electro-acoustic instrument, disturbances of the sound spectrum may appear at different points in the sound chain. These disturbances are more commonly called audio interference. This noise can be generated by different elements and it can be (very) difficult to identify its source. To find it, it will be necessary to proceed by a process of elimination. You’ll have remove and disconnect one by one the elements in order to identify the source emitting the interference.

Once the source is identified, you can try to find a solution in order to reduce and eliminate the noise if it is possible. In any case, note that dealing with interference at its source will always be much more obvious than dealing with it at the sound chain’s output. If you think that a sound engineer will have all the solutions to delete an interference, think again! The simplest solution is always to remove it or at least to reduce it to the maximum so that you can then rework it numerically.

When put end-to-end, these interferences can generate an infernal hubbub for the members of the audience and the sound engineer.

During the balance, or before starting a studio recording, try to identify the cause so you can reduce and, if possible, remove this inconvenience. We have listed several parameters that can cause interference in your sound chain.

Microphone & sensors

Equinox electric violin

Generally, electric violins are equipped with piezoelectric sensors. These sensors are intended to “translate” the vibrations to which they are subjected into an audio signal. We are talking about the vibration of the strings in the frame of the violin. This technology has the advantage of limiting the appearance of interference. The better your pickup is, the less interference it will generate.

Choosing a good quality electric violin, equipped with a piezoelectric sensor on each string, will limit or even eliminate most of the interference.

Electrical interference

If you use a magnetic sensor, other difficulties related to the magnetic field of the electrical signal may occur. First, the alternating current can interfere with your magnetic sensor. This is the “bzz” we hear frequently in electric guitars.

Very often, if you turn in certain directions, you will find a position that generates a lower interference… This position will be the ideal position to play in the studio while recording as little noise as possible. In the context of a concert, needless to say, you should not play turned back on the audience, you will have to find another solution.

Earth loop or ground loop

DI box

The problem of the ground loop is that it can also generate an interference. The ground loop is created when several elements used in your sound chain are connected to different electrical outlets. Since the current is alternating, its frequency will be different from one plug to another, which will generate the interference.

In this case, you can use the “ground / lift” switch of your DI box. It will cut the ground conductor between the input and output circuits and stop the interference. This type of switch sometimes exists on amplifiers and will play the same role.

Lighting

Lighting is also a disruptive element that can generate interference. Particularly neon lights that generate a permanent “buzz”. If you have good ears, you must have heard that neon lights emit this noise as soon as they are lit. The solution: limit the number of light sources in the studio or use another type of lighting.

Lighting using a dimmer will also generate more or less noise; we are talking about those switches that allow both to turn on or off a light source, and manage the light intensity. It is found in most North American homes (and much less in Europe). These dimmers can accentuate interference. In that case, find the position that will generate the least noise. Normally, this will be the position in which the dimmer is turned to the brighter setting.

Preamplifier

In the interest of consistency in the levels of the audio signal, sometimes a preamplifier is necessary in order to control the impedance of the signal created by the instrument. A poor-quality preamplifier can generate a “blast of air” at high volume. Favor electric violins without integrated preamplifier or otherwise, those equipped with a passive preamplifier. Not having a preamplifier will allow you to better control your sound and effects chain.

Cables

jack cable

Always use a shielded cable to connect your electric violin to the next component of the sound chain. Most audio cables are shielded to minimize interference. So, they are equipped with a ground conductor. The role of this ground conductor is to protect the signal from any interference.

Do not use excessively long cables

The longer the cable that connects your violin to your amp or effects pedal, the more likely it is to pick up interference, such as unwanted radio waves. They will add to the audio signal and create more or less loud noises. It is better to use cables that are not too long.

Do not coil them in a circle

We tend to coil our cables in a circle to store them, and not to unroll them in their entirety when we are on stage or in a studio to avoid having long cables lying on the floor. However, when leaving the cables coiled, they will play the role of an antenna that will capture the interference waves and therefore generate noise. Unwind them to limit the interference!

Cables in bad condition

At first sight, all your cables seem to be in good condition, yet after unwrapping and wrapping them, pulling them or walking on them, the internal wiring may break. If the ground conductor is broken, interference will be automatically generated. It will be necessary to test them one by one to identify the cable which is at the origin of the interference. Once identified, there is no need to keep this cable, replace it and discard the old one.

A wireless system

A wireless system should not be affected by the distance between the transmitter and the receiver as long as it stays within its range. On the other hand, a poor quality wireless system is likely to create a high-volume blast of air. It is better to inquire before buying the first wireless system you find on the market…

Multi Effects Processors and effects pedals

effects pedals

The effects processors are a double-edged sword. They will improve your sound if you use them correctly and on the other hand, can completely degrade it if the settings are not well adapted. Note that a very low-end multi-effects pedal will invariably create a blast, which traduces into noise.

Enchain the effects in a logical order (see the article “Electric Violin Effects Chain“) to minimize the formation of interference at each stage. Also, be sure to correctly adjust the input gain in your effects processor and preferably choose good quality effects.

Do not hesitate to use sound cleaning effects such as the denoiser or the gate.

The sound diffusion system

The sound diffusion system can be either:

  • an amplifier
  • a PA system

A poorly tuned or poorly designed sound diffusion system will be a significant source of noise in the sound chain. If this interference is not eliminated upstream or downstream, it can quickly become very annoying or even unbearable. You must have heard it, we are talking about the “bzzzz” we hear when musicians stop playing on stage and the sound diffusion system is still active.

Attention, the sound diffusion system being at the end of the sound chain, it is not always at the origin of the interference. It can retranscribe the interference produced by an element or elements located before it in the sound chain. To identify the source of the interference, proceed by a process of elimination by testing the elements that compose your sound chain. Once identified, try to remove or reduce the interference.

Again, the quality of a sound diffusion system (amp, speakers, sub, etc.) will depend on your budget. It is better to emphasize the quality of the sound system to its power. A good 30-watt amp will always be more striking than a big low-end 100-watt amp. Low-end amps are usually a source of a lot of interference!

amp and PA system

Images: Unsplash – @litangen, @gabrielgurrola, @juandinella, @antoinebst