Understanding Effects: Chorus

Chorus is aptly named so as it attempts to emulate the effect you would hear in a vocal choir, or any other setting where two instruments are playing a part in unison. The only caveat here is that the effect typically works in the pitch domain. Some definitions of chorus will include differences in the time domain (IE delay around 30ms) but chorus guitar pedals typically don’t work in that way.

To understand this effect, we need to understand beat frequencies. Beat frequencies occur as a third “note” when two pitches which are slightly out-of-tune are played against each other. For example, a note is played at 60hz and another note is played at 61hz. The resulting beat frequency will be at 1hz or one cycle per second. This is perceived as a wavy-ness in the sound. This creates the unique choral effect we associate with vocal choirs. For the purposes of guitar, we only experience one more “voice” as opposed to multiple doubling voices in a vocal choir (e.g. 4 tenor singers). The guitar’s signal is processed to modulate in pitch at a specified rate and amount and then mixed back in with the original signal.

Mix/Level

If you’ve read my other articles on effects, you might realize by now that a common theme is that less is more. It’s not a rule so much as a guideline to keep you out of trouble. You can get away with a little more when it comes to the chorus effect but it will start to give it a surreal and metallic quality if you mix in too much of the processed signal.

Depth

This parameter controls the amount that the original pitch is modulated in pitch. In other words, think about it like you’re controlling how out-of-tune two voices are to each other.

Rate/Speed

This controls the rate at which the pitch (set by the depth parameter) modulates at. In other words, you can think of it like being able to control the speed of a vibrato by a vocalist in a choir. Typically, depth and speed will have an inverse relationship: the more depth you use the less the speed will be needed to have an audible difference.

Get Creative

Some interesting things can happen when we use extreme settings with this effect. The most notable user of extreme chorus settings is John Scofield. He attempts to recreate the warbling sound of a rotary (Leslie) speaker that is typically used by electric organ players. This involves a high rate/speed setting and a mid to high level of depth. Another cool use is to set the mix so that it is 100% wet, so you only hear the affected signal and none of the original guitar sound. This reminds me of the sound of tape warping where the speed of the tape reel affects the pitch of the music. The possibilities are endless!

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You Ears aren’t on Your Knees

This is going to be another quick tip for amp positioning.

Do you keep amplifiers on the floor while performing? If you answered yes, you’re not going to be projecting the sound in the best way, to yourself and the audience.

Think about it for a moment – the amplifiers are way down there, and your ears are way up on your head. Why would you point the amplifier in a direction other than where your (and the audience’s) ears are? Loudspeakers project sound in a very directional way. That means that the more you shift from being directly in front of the speaker, the greater the change in perceived tone. Try this experiment: Have an amplifier at head level, about two feet away from your face. Listen to some music in that position, then shift over by a foot to the left or right and notice the change in sound. Pretty noticeable, right?

The truth is in most situations, it’s near impossible to line up everyone’s ears to be directly in line with your amplifier speaker. You should, however, aim it in the general direction of your ears (and your audience’s) by tilting the amp or by getting it off the floor onto something closer to ear-level. A side benefit to doing this is that an amp will be decoupled from the floor which can help avoid low frequency resonances if you’re on a hollow stage.

This tip isn’t to say that this is the definitively CORRECT way of positioning an amp on stage. In some situations, you may only want the acoustic sound on stage. You would put the amp, therefore, in front of you to avoid hearing it. If a stage floor is elevated to the audience’s ear level, then placing it on the floor might be the best option. The goal is to figure out the optimal amp position for your given situation.

I hope this helps to get a better sound on your next gig!

Keep the Amp on the Left-hand Side

Simple tip to keep you amp from feeding back as much: keep it on your left-hand side.

Okay, I’ll be a bit more specific. Keep the amp on the opposite side to where your guitar body is. If you play left-handed, then it will be your right-hand side.

Why does this work? Typically a guitar amp is positioned behind a guitarist, which means the sound coming out of the speaker will be projected towards your guitar. A guitar, by design, is a big resonating box. Unfortunately this creates a perfect scenario for feedback: the sound being projected from the speaker is played into the guitar, the guitar body resonates at those frequencies which get picked up by a microphone/pickup and is fed back into the amp. By placing the amplifier on the side opposite to the guitar body, the sound is projected away from the guitar body and breaks this cycle.

This isn’t going to be a cure-all for all feedback problems, but it’s one of many things you can do to prevent feedback from destroying your gig. Hope it’s useful to you!

Practice with a Plan

Let’s face it, we all have times when we are short on practice time. Work, school, and social commitments cut into your time that could otherwise be spent improving your guitar abilities. We simply can’t abandon certain responsibilities, so it’s important that we make the most of the little time we do have. The most effective means to do this is to plan out exactly what is going to happen in your practice session.

How should a practice session be structured? There is an infinite amount of material you can practice. What is important is that we challenge ourselves continuously. In other words, we should be prioritizing that which we are not good at and to decrease the amount of time we spend reviewing what we are already good at. Many students can fall under the illusion that they are practicing by simply playing their favourite songs, which they are likely performing well already. Even worse, they’ll do it while watching TV and only be passively engaged with the material. This is not effective practicing, it’s simply maintenance of what you already know. Reviewing material has its place, but it should be less of a priority.

The first thing you should practice, perhaps after a short warm-up, is the most difficult challenge on the menu. Difficulty is subjective, so don’t pick a topic that is way beyond your reach. Simply do something that challenges you and keeps your mind engaged. Depending on the time constraint, you might not even get through the entirety of the topic at hand. That matters less if you consider that you will have opportunities in the future to revisit it. Repeat this process until you’ve mastered the topic, then move on to a new one. You may not be satisfied with the small progresses that are made in each session but over the long term you will be able to make far more progress than if you were to choose the easy stuff. The easy stuff is gratifying in the short term but will leave you feeling like you’ve wasted time when there is no progress over the long term.

I guarantee that if you can practice with this mindset, progress is certain and you’ll be surprised at how much you can accomplish even with limited time!

Acoustic Guitar Mic Placement

Amplifying an acoustic guitar with a microphone can be tricky. The instrument is often susceptible to feedback and sound engineers frequently ask you to use a pickup to compensate. If your pickup system is a soundboard transducer (like piezo elements under the bridge saddles) then the result is a highly unnatural sound that only partially translates the beautiful acoustic sound. However, knowing a few things about microphone placement can help tremendously in taming feedback while still getting a natural sound that only microphones can capture.

Proximity Effect

In the microphone world, there is something called the proximity effect. The proximity effect describes the tendency for a microphone to pickup more bass frequencies, the closer it’s placed to the sound source. This concept is important in taming low frequency feedback and getting a balanced sound. A common mistake is that guitarists will tend to position themselves so that the microphone is as close to the soundhole of the guitar as possible. The area directly in front of the soundhole is where much of the low frequencies of the instrument are picked up; combined with the proximity effect it creates the perfect situation for feedback to occur. To solve this, try to stay about a foot away from the microphone when possible, and angle it away from the sound hole. The 12th fret is a common target to point a microphone towards. If you’re using a clip-on mic, try and follow these guidelines with the limited mobility of the microphone.

If you’re still getting feedback after placing the mic in the optimal position, try using (if available) a phase switch to reverse the polarity of your signal or use an equalizer to dial out the problem frequencies. Just remember these options are best used AFTER you’ve gotten a balanced sound through microphone placement. I hope this helps in getting a better live sound for you!

Understanding Effects: Compression

Compression, short for dynamic compression, is a topic that confuses pros and amateurs alike. In fact, it can take some people years to thoroughly understand how it is affecting our audio signal and to fully utilize the many applications of dynamic compression. I believe the confusing aspect of this effect is that the difference in sound can be quite subtle, making it difficult to associate the turning of dials with the change in sound.

Here’s a step by step of what happens to a signal going through a compressor. First, a volume threshold is set. The audio signal needs to go past this threshold in order to activate the compressor. You also need to understand that a compressor will only affect the part of the audio that crosses this threshold. You can also control how fast the compressor reacts to the signal going above and below this threshold by controlling the “attack” and “release” setting. These controls are important in targeting the portion of the signal you want affected/unaffected. Once the compressor is triggered, the signal is reduced by a set ratio (oftentimes 2:1, 4:1, 8:1). Say for example, a signal that is 6dB over the threshold will now only be 3dB loud with a ratio of 2:1.

Threshold

The threshold is the minimum amount of volume needed to engage the compressor effect. Therefore, if the signal you are dealing with is too quiet and below the set threshold, the compressor will never engage. The compressor releases after the signal falls below threshold. On many stompbox compressors, the input gain is adjusted relative to a fixed threshold. In other words, you control how much signal goes past the threshold by adjust the volume of the signal, instead of adjusting the threshold itself.

Ratio

As explained earlier, this is the ratio at which the original signal is compressed. The greater the ratio, the more dynamic range (difference between loud and soft parts) is lost. For guitar pedals, this ratio tends to be fixed but generally set around 4:1 or 8:1. When the ratio is 20:1 or greater, it is considered to be functioning as a limiter and has other uses associated with it. Lower ratios will have a much more transparent effect on the sound.

Attack/Release

The attack and release parameters may also be fixed on certain guitar pedal compressors. These controls adjust the speed at which the compressor engages and releases when crossing the threshold, and is typically measured in milliseconds. It’s important to adjust attack so that it is affecting the part of the sound you want to, namely the transient or the tail. The transient is the “attack” of the guitar string when being picked. If you were to look at a visual representation of a guitar note in a DAW, you will see the attack as the loudest portion of the sound and the tail of the note as a steadily decaying waveform. Generally speaking, you want to set the attack at a speed which avoids compressing the transient, and engages on the tail. The release setting will be more dependant on the style of guitar you are playing. A funk rhythm guitar will likely have a quick release so that it doesn’t affect the next strum, where as sustained lead notes will have a slow release to keep notes from dying out too soon. Some digital compressors will have an automatic release control that responds intelligently to your playing.

Make-up Gain

A compressor, by definition, will reduce the overall volume of a sound. The make-up gain is there to “make-up” for any lost volume by adding some gain after the effect has taken place. It is meant as a corrective tool, so all you need to do with it is to set it so that the processed sound is at the same volume as the original signal.

If your guitar tends to have loud/soft spots, or you’re still having problems controlling the volume of your picking or strumming, there is a lot to be gained by using a compressor. What you may lose in dynamic range, you will gain in dynamic consistency which is an important part of genres such as funk. Furthermore, it can also be a way of protecting your precious equipment by reducing sudden spikes in volume that can harm speakers and overload power amps. Tonally speaking, it’s a great way to add punch and warmth to your guitar sound in a subtle way and might just be the thing you need to take your sound to a “professional” level. Have fun!

The Signal Chain

I’ve referenced the idea of the “signal chain” in some past posts, and how it helps to conceptualize how your sound is developed through the various equipment that your guitar passes through. It’s a concept that will help you achieve the tone you want, consistently.

There are a couple of adages in the audio engineering world (and many other professions) that goes: “crap goes in, crap comes out”, or sometimes “you can’t polish a turd.” They both mean essentially the same thing: get it right as early as possible or you will pay for it later with less than desirable results (and time wasted). There is no “fix it in the mix” and there is no “my garage sale guitar can sound like Eric Johnson if I get the right amp.”

How should guitar players aim to get it right at the top of the signal chain? The first step is your technique. Have you ever noticed how an artist sounds like themselves no matter what gear they play through? This is because their technique and stylistic approach to music has been developed for years to create their sonic signature. Having well developed technique will also enable you to adjust your playing to any guitar so that you may get the best possible sound out of it. Always be looking to improve your technique and you will never lose your sound on any piece of gear.

The next step in the chain is the guitar. If you’re playing a solid body electric guitar, the strings and pickups are going to create the biggest difference in sound. If you’re playing an acoustic guitar, the wood of the soundboard will be the biggest contributor to tone. When it comes to strings, the materials matter but the biggest factor may be string tension. String tension is affected by factors like string gauge and action. It will affect the amount of sustain you can get from your guitar and will also change the amount of attack relative to the sustain. Pickups are a matter of personal taste but the most important factor is whether they are single coil or humbuckers. Choose from the many hundreds of after market replacements, what will complement your style the best.

Before we get further down the chain, I just want to mention one thing about connectors (IE patch cords, cables, etc.) Your monster cable, gold plated connectors, oxidation-free vacuum-sealed whatevers are pointless. Don’t invest your hard earned dollars into them because they won’t make a difference. I recall an experiment done by audiophiles where people couldn’t tell the difference between Monster Cables and a coat hanger. The two most important attributes for cables are that they’re insulated well and are durable.

From the guitar, the signal travels to the amp. A lot of people say that amps are probably the most important factor in getting a great electric guitar sound, but see how far down the signal chain it actually is? If we had gotten all of the previous components wrong, then no amp is going to remedy your sound. However, if you had everything right to this point, your guitar stands a chance of sounding good and even amazing on many amps. The (combo) amplifier can be further divided into its components: the preamp, poweramp, and speaker. You can take what you get with the combo amp or delve into the world of customizing your amplifier setup as well. That’s a massive topic that’s beyond the scope of this blog entry.

The environment/room is the final stop in a signal chain before the sound reaches your ears. In most scenarios you won’t have the option of customizing the environment, but it’s important to learn to compensate for it. Some rooms have hard surfaces like concrete walls that will create a cacophony by reflecting the sound everywhere. Avoid using reverb in these situations as they’ll just muddy up the mix. Other rooms may create resonances as certain frequencies that will need to be compensated by using an equalizer. Even the amount of people in a room will affect your sound, as human bodies can dampen sound reflections.

I hope I gave you some ideas on how to think about building your sound in a logical way. Enjoy!