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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Mixing Gypsy Jazz Guitar

There are so many great Gypsy Jazz records out there now that are well produced; Selmer #607 and Les Doigts de l’Homme are among my favourites. However, there are even more poorly mixed records out there.

I don’t blame the mix engineer. This is a small niche in the jazz world and requires an entirely different approach to mixing the guitars. If you haven’t listened to a ton of Django Reinhardt records and modern Gypsy Jazz artists, you can’t expect them to be aware of the different roles the guitars take in this genre. Having experienced mixing in this style myself, I’d like to offer some advice to those who might be less informed in this style and looking for some guidelines to follow.

Let’s talk about the instrument itself first. These guitars (Selmer/Macafferi design) tend to be voiced as a lead instrument rather than an accompaniment instrument. Tonally, it translates to having much more of a mid range bite rather than a deep low end and shimmering presence. One huge mistake I hear frequently is giving these guitars a shelf-EQ boost in the presence (>4khz) which results in a harsh and unpleasant attack.

When the guitar is not playing lead, it will be playing rhythm. This isn’t to be mistaken with sustained and open chords ringing behind a lead. The guitar actually replaces the drums as a percussion tool, since this style is usually performed without drums. A rhythm guitarist will generally play short chords with a heavy backbeat that imitates a snare drum. To that extent, applying EQ and compression in a similar approach to drums would yield better results than the traditional approach to mixing guitar accompaniment.

Now that we understand the roles of the guitars, I’d like to address the history of recording technology and this style. Django Reinhardt’s recordings are often considered the holy grail, but the tone on his records are a result of the technology available at the time, as much as his technique. Ribbon mics were the norm back then, and recording in mono around one microphone. The high frequencies were attenuated even further by the medium of vinyl records. There’s no reason to slavishly follow this approach (although some have achieved an uncanny resemblance to the original recordings). Now you have plenty of new technology to create a compelling modern sound, but it’s important to understand what the ears of the audience has been trained to expect.

Let’s get down to the practical part now. EQ and compression are the most commonly used mixing tools so let’s talk about those. For EQ, it seems fairly obvious now that you will likely have to cut the high frequencies instead of boosting them. Pay close attention to the pick attack of the players, as it is probably the most distracting part. Low frequencies can be extremely lacking in these guitars so sometimes a little boost in that range can help thicken up a sound. If the sound is otherwise pleasing, you can apply a high pass filter to make room for other bass instruments in the mix.

One component of the high frequencies is pick noise, which is especially problematic in this style.  Players tend to use a technique called rest-stroke picking that accentuates the attack. If an equalizer doesn’t quite cut it for dealing with this annoyance, a multi-band compression can be a handy tool. I’ve sometimes used vocal de-esser (essentially a narrow band compressor) to specifically weed out this problem area in a natural and subtle way.

A trend that’s becoming increasingly common is to compress the crap out of the rhythm guitars, to give it an extremely aggressive and punchy swing feel. The guitars are often played with very little sustain so a fast attack/release is recommended. If there is a doubled rhythm guitar, you can get a wider stereo mix by hard-panning the two, a common trick in rock mixes.

Finally, any mix should always be tested against a reference track. My recommended reference recordings are (if you haven’t guessed already) the Selmer #607 record series, and the Les Doigts de l’Homme records (particularly Mumbo Jumbo and Couers des Vivants). The Selmer #607 series is particularly interesting as Ghali Hadefi’s production style evolves over the course of the records.  It’s particularly interesting to hear the latest Selmer #607 record and its treatment of the high frequencies. To me, it borders on sounding unnatural but the result is very smooth on the ears. Les Doigts de l’Homme records have incredible arrangements that do a great deal to create an amazing mix but the rhythm guitars is where it particularly shines.

This ended up being a little long but I hope it helps you create a more compelling Gypsy Jazz mix!