Audio Recording Issues – Overtones That Overstay Their Welcome, Part TwoNow that we've addressed some of the potential scenarios that can come up in sessions that produce unwanted overtones, let's look at some EQ solutions that make the most sense.
The goal in properly addressing and resolving specific overtone issues is to play the offending track against the mix. This may be tricky, depending on what role the track plays in the prominence of the mix. Set up as many final elements in the mix as possible. I recommend slowly fading in the track you are operating, on and listen for the tonal issue. Does it come across like a specific Frequency or set of Frequencies, or does it tend to clash with legit notes from other instruments? Is it a wide range of Frequencies, narrow, or multiple? Usually, you can use a fairly standard bell shape to reduce the effect of the overtone. If it has the characteristic of a specific pitch, you may want to use a narrow EQ to reduce its effect.
Some overtones may be built into the fundamental notes, like a Hammond organ for example. The notes on a Hammond are controlled by multiple sliders, each controlling a different pitch, or harmonic order. Quite literally, the tonal character of the organ's sound is being controlled by adding or subtracting octaves to the fundamental. These may sound fantastic until final mix, where they resonate the wrong way compared to other notes. Usually, a medium "Q" can reduce the specific Frequency range where it gets into trouble.
Where Program Equalizers, like Pultec-type designs, are very effective for enhancing wide portions of sound, like the entire mid-range, specific low end or high end sweetening, they are not perfectly suited to the surgical elimination of overtone issues. A flexible multi-tasking tool like the AMK-9098 can handle tasks with multiple width narrow band EQ's but also uniquely shaped EQ slopes and curves. EQ's like the Focal Point 115HD are flexible for certain surgical processes as well, but this EQ has a unique tonal character of its own. The 9098 and 115HD can be extremely useful with very different, equally phenomenal high end sound. Where the 9098 has an aesthetic quality that is very precise and musical, the 115HD is gorgeous and rich in texture. In some circumstances, one EQ may eliminate issues easier because of the right mix of flexibility and precision, where the other may be helpful because of its ability to correct some issues while simultaneously adding some of its own rich overtone qualities into the mix. These EQ choices then become creative choices, and not just solutions for eliminating an issue.
In the case of a drumset that has been carefully tuned to work with the songs being tracked, we sometimes still run into issues despite our best efforts. Often, the initial attack of tuned Tom Toms are clear, bright, and have an attack that works great with their use, but as they sustain, the vibration of the tone becomes resonant in mid and lower Frequencies that sound like an annoying atonal hum against more important elements. This may be accentuated by the use of compression that gives the attack desired. As the toms shift from sharp, bright attack to long sustain tones that hum, and become increasingly muted, the compression continues to bring up some of the level of the extended tail, making it conflict with musical elements in the song. Individual EQ on the toms may be the most helpful way to avoid further trouble. Some may choose to gate the Toms in traditional mixing and perhaps in the DAW as well, although it is not a well-taught method in modern tracking. This can lead to further issues and may not be as effective as one would hope. In this case, a Program Equalizer, like a Pultec-Style design, or a regular "Q" width bell, can reduce the center Frequency of the hum. With 2-3 Toms, this EQ can be done on a single tom bus without reducing the positive qualities. Just a dB or two of reduction on a couple of resonant tom tones can eliminate the conflict.
I hope this gives you some ideas for digging yourself out of certain technical issues with overtones. One might say that this is a way to get 'over' the trouble with overtones!