photo by bnsd
Do you suffer from the low-end blues? The symptoms include instruments lacking clarity, vocals lacking distinction, and a general feeling that “something’s rotten in the state of Denmark.” You’ve never been diagnosed with it until today. Time to determine the source of the condition and prescribe a cure.
Consulting with churches on their audio quality, I’ve found a handful of common problems and the most common is excessive low-end frequencies in the mix. It’s the result of many factors, three of which are outlined below.
Three Reason for the Low-End Blues
1. Poor bass definition
I didn’t say “Poor Bass EQ” because the blame doesn’t fall entirely on the sound tech. The tone of the bass guitar comes from the bass, the bass amp, and any effects pedals the musician uses. And believe me, I’ve heard a wide range of tones coming from a bass player. I’ve heard a mush of low end coming from a bass channel and I’ve heard what I’ll call outer space sounds.
Why it’s a problem
You’re at the mercy of the musician and whatever they send down the line. A bass tone without definition is just a source of low-end mush. But even a great bass tone might have more low end than needed. It still needs to be distinct from the kick drum.
What to do
Listen to the raw tone coming through the bass channel. All of the mix work will either be working with this sound or against it. If the bass is sending mush, it’s not going to be easy. EQ the bass so it’s distinct from the kick drum. Don’t think that just because it’s a bass that the low end should be cranked. I’ve cut a bass channel below 40 Hz because it cleared up the mix and gave the bass guitar definition. Many of the key bass frequencies exist above the 100 Hz mark.
The biggest way to improve bass definition is to listen to recordings of the song. Youtube, Spotify, iTunes, Rdio, whatever works, just pick one and listen to where the bass sits in the mix. Know the song before the sound check so the bass sound is in your head. Put on headphones and listen to the recording while mixing if it helps. Compare the recording to your mix to determine what needs to be done.
2. Poor keyboard mix
Keyboards can create a wide range of sounds and frequencies. These sounds can drop into the same range as bass and electric guitars, even drum toms.
Why it’s a problem
The more similar frequencies occupying a mix, the less instrument and vocal distinction. A song using a bass, an electric rhythm guitar, and the normal drum kit is already filling up the lower frequencies and requires proper EQ’ing for separation. By adding in a keyboard, it’s another source of low end, the amount depending on the keyboard voicing.
What to do
Apply the high-pass filter and modify the EQ so the keyboard fills in the mix as intended by the arrangement. By cutting the lower frequencies, a simple volume change might be all that’s needed. I find by using a substantial low-end cut on the keyboards, not only does it clear space for the lower instruments but it also adds clarity to the keyboard.
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3. Low-end flooding
The more microphones on stage, the more channels capturing stage volume. Add a bass amp and drum kit on the stage and there’s low-end frequencies bouncing all over the place, both from the amp and drums as well as through the monitors.
Why it’s a problem.
Every little bit matters in mixing and when it comes to microphones, every little bit of extra low end adds up to a lot of low end in the house mix. Low-end frequencies will bounce around the room, lasting longer and flooding the room.
What to do
Apply a high-pass filter to all vocal microphones. Start around the 80-to-100 Hz range. On mixers with variable HPF frequencies, roll the filter up until it negatively affects the sound, then back it off. This can range anywhere from 120 to 220 Hz.
If it seems like I’ve been talking about HPF’s a lot recently, it’s because I have and because I believe they are under-utilized.
Next, use some form of drum shield to reduce the lows. But wait, there’s more! Here’s where an oversight can be costly. If the drummer is sitting in front of a flat surface, the drum shield is only going to reflect the sound back to the wall and then back into the drum shield and the microphones. To control the lows, use a full drum enclosure or cover the wall with sound absorbing material. This can be anything from acoustic panels to heavy theater curtains.
Finally, in the case of stage amps, reduce them to only their required volume and point them at the musician. For example, a guitarist with a guitar amp needs the amp pointed at their head. If they are using a full-stack amp, then mic the amp and turn down the amp. If they want the amp cranked, look into isolation cabinets.
The Take Away
The low-end blues can be overcome. Focus on these three points and listen to the results after each one. Eventually, the low-end frequencies will be reduced in the room and clarity will return to the mix.
Cajundaddy says
October 30, 2014 at 12:39 amYes, getting rid of the mush goes a long way towards hearing the instruments in their natural state. Compounding the problem is that low frequencies below 150hz are omnidirectional so lows from the floor wedges, subs, and mains are wrapping around and filling all the live mics with mush. We essentially use a 150hz HPF on all female vocalists, 80hz HPF on every input except Bass and kick with a 40hz HPF on those. This eliminates most of the stage rumble and lets the voices and instruments shine through. Now mixing and balancing is much more manageable and you no longer have to get eq extreme with keys and guitars turning them into unnatural sounding harpsichords and mandolins.
Be blessed
Quaid says
October 23, 2014 at 12:23 pmThe EV RE 510 microphones have a built in switch to engage a 200 Hz., 6 dB per octave low cut filter. I’ve been eyeing these (for more than just the recessed high pass), interested in using them as an instrument and vocal mic.
The built in gradual filter would help with clearing up any instances of mud. In addition to the board’s high pass. The ones I don’t have the built in high pass engaged on can be marked, like with a certain color mic cord, and/or colored tape on the mic, and I could dedicate those for sources that would be benefited by having it’s low end reinforced in a more linear manner.
Anonymous says
October 22, 2014 at 1:19 pmAt our church we used the HPF on every channel this past sunday and the difference in clarity was amazing. We had just completed a training weekend sponsored by Shure, Yamaha, and Elation and our local church which taught us more tips, tricks, techniques that I would even try to describe here. Next time I have a chance to run the board (we rotate operators) I plan to use the bass tip in this article.
Anonymous says
October 21, 2014 at 1:38 amI’veI played bass for years and always wanted to run sound just never had the opportunity lack of musicians. This past year I finally got to start running sound I still have to play bass on occasion. Lastmonth I install flatwound strings on my guitar for the first time. I love these things!!!!! The sustained goes on forever and the attack marries very well with the kick drum. Plusno finger noise on the neck. I never could EQ out the metallic sound roundwound strings without losing some of the tonal characteristics of the attack. Try them they may help clear up your muddiness. I use the La Bella deep talking strings I also recommend the De Addario chrome flatwounds
TJ Wuth says
September 10, 2014 at 12:02 pmGreat post Chris. Along the lines of the Bass guitar it’s also important to know where you’re picking up the signal and how to change that point. Many of the bass amps in use today have direct outs and post/pre switches for the EQ and fx loop. Simply switching that pick-off point from post to pre can often clear up a lot of the issues with the bass. Unless I’ve got a stellar bass player I prefer to send the bass to a separate good quality DI and then use the Thru output of the DI to send to the bass amp. I then let the bass player know that they can create the tone they’re most comfortable with on stage without affecting the house mix and we can work together on a good stage volume for the amp. This is especially helpful for those bassists that just don’t have a good grasp on how to properly use the gain and volume knobs on the amp.
Keyboards can definitely be a thorn in your mix. One patch sounds great on one song and the patch on the next song just wants to fight you. Along with your excellent advice of cutting the low end, if you have a good keyboardist, try an experiment and ask them to move up an octave before touching the EQ and just see how it sounds in the house. I’ve had several occasions where that simple change made all the difference. I should note that I’ve also tried the opposite (ask them to move down and octave) if their patch is stepping all over the vocals and guitar parts.
One more thing, if you engage the HPF, please don’t subsequently turn up the low shelving EQ. I can’t tell you how many times I’ve seen newer techs fighting their own EQ settings.
Chris Huff says
September 12, 2014 at 8:34 am“if you engage the HPF, please don’t subsequently turn up the low shelving EQ. I can’t tell you how many times I’ve seen newer techs fighting their own EQ settings.”
I’ve done it once or twice. Then I look at the HPF and think “doh!”
Quaid says
October 23, 2014 at 12:00 pmSo, if you engage a 75 Hz channel lowcut, and boost an 80 Hz shelving filter, you can get…………………
mud.
No matter what brand of mixer you use, shelving filter “overlap” means that you don’t just boost frequencies below the stated EQ frequency, but a lot of frequencies above the “corner” of the curve. So doing + 7 dB on an 80 Hz. shelf EQ gives you +7 dB @ 80 Hz, and maybe + 4 dB at 150 or 200. Again, mud.
An EQ boost like that will even affect frequencies up to 1,000 Hz.
You can check, for example, the Mackie Onyx 1640’s manual for a visual diagram of this.
Not that Mackie is horrible, many EQ circuits do this. Some products allow you to cut back the amount of boost outside of the shelf’s intended range, which helps you get more on target bass frequency boost, and less mud.
Scott Lake says
September 10, 2014 at 10:19 amThe low cut / high pass filter switch is probably the most under-utilized control on live sound gigs. My rule of thumb is to engage it on every channel except bass and kick drum and possibly the lowest rack tom in the drummer’s kit. I’ve not run across a situation where I had to go back and disengage the low cut / high pass filter. I learned this from none other than a quote from BT, or Brian Trepanier – the stutter edit dance music producer. He made this comment in an article in either Keyboard or Electronic Musician magazine. With digital boards, you commonly have control of the cutoff frequency as well.