This installment of audio tips has a similar theme to the last one, in that we will continue to deal with methods for cleaning up unwanted artifacts in the mix. We previously dealt with the use of high pass filters to clean up unwanted audio clutter and cloudiness. In this case, we’ll examine ways to reduce some of the sources of, what I call, stage mud. Stage mud is my way of describing what occurs when acoustic energy generated by the instruments on stage (drums, monitors, amps) begins to cloud the clarity of the sound reinforcement system (PA). Without exception, the level of the stage noise generated will conversely dictate the necessary level of PA energy needed to overcome it. In other words, the louder the din of the stage, the louder the PA will have to be driven to overcome the adverse effects of the “stage mud’. The PA must be louder than the stage mud in order to insure a clear and intelligible experience for the audience.

It has been my experience (and many others I’ve heard from) that this effect is exacerbated by the fact that most musicians are on the verge of deafness and insist on turning their amps to 11, and that many drummers have never learned to play below the audio threshold of pain. This, in turn, causes each musician to compensate by turning up their respective instrument (or monitor), creating a competition for dominance. Now, while there is definitely some truth to this, the fact is that many (if not most) church buildings are inherently flawed in their acoustic design, adding significantly to this problem. Hard, untreated floors, walls, and stages are the norm in most older church buildings, gymnasiums, and converted storefront locations that house many ministries. Adding to the problem is the fact that many of these facilities are using an inadequate PA system, improperly installed with inherent design flaws and poor coverage (but that’s another subject!).

All of those potential PA problems aside, the question is, are there any practical steps we can take to reduce the effects of this phenomena? Thankfully, yes, there are some very practical ways that we can substantially reduce the dreaded stage mud that plagues so many congregations. Some of these suggestions will require a capital expenditure, while others will only require a few minor tweaks to what we already own.

Due to its acoustic nature, one of the toughest culprits to tame is the drum kit. Unfortunately, it’s the drummer’s overall stage volume that sets the bar for everyone else to adjust their relative levels. While much can be said for a well-trained and disciplined drummer keeping his/her own volume in-check, there are limits to how quietly a drummer can possibly play. One way to offset this limitation is by surrounding the drum kit with a clear plastic shield (available through most music stores). Some of these even incorporate acoustically absorptive panels on the lower half of the shield, as well as a complete absorptive-panel roof option. I would only suggest the roof option for the most extreme problem cases, as it has its own limitations with ventilation, monitoring, etc. The drum shield is a very good place to start when trying to lower the overall stage volume.

Next up is the bass guitar. The bass is also a tough one to overcome in most spaces, as it tends to be omni-directional, and the subsonic frequencies like to linger in most untreated spaces. My answer to this one involves the use of some relatively new technology, as well as a little flexibility and discipline from the bass player. The technology employed is a product called a Butt Kicker. It is comprised of a small (3’x3’)
platform that the bass players stands on. Attached to this platform is a little transducer motor, driven by its own amp, that is connected to the bass player’s rig. The idea is to roll-off some of the low frequencies on the bass player’s amplifier (which cleans up the bass frequencies on stage), while still allowing the visceral experience of the lower frequencies to be felt by the bass player standing on the “shaker”. It is a different concept that may take a little getting used to, but is very effective in curbing the effects of low- frequency “hang” in the room. It is also great when coupled with in-ear monitors, used in-place of the amp altogether.

Now comes another tough customer, the electric guitar amp. One of the problems with electric guitars is that most sit fairly low to the ground, which puts the amp off-axis to the player’s ears. In other words, it’s usually facing the back of his legs! One way to correct this problem is to put the amp on an angled (and elevated) amp stand (available at most music stores). This gets the amp up, off the floor, and angled at the player’s ears. It’s also not a bad idea to place the rig in front of the player (looking back at him), so as to direct the energy directly toward the front of the player. Again, this allows for dropping the amp volume, which cleans up the stage, sonically. If in-ear monitors are being used, another suggestion might be to place the guitar amp in a sound-proof box or off-stage room (mic.’d of course), to eliminate the amp noise on stage. These can also be purchased through a local music store.

Another source of stage mud is the monitor floor wedge. My philosophy about monitor wedges is that they do not have to be full-range to be effective. For most applications the monitor EQ can be set to significantly reduce the amount of low to low-mid energy allowed to pass through them. I like to cut much of the low and low-mid frequency content using a 1/3 octave graphic EQ on each monitor send. This way, the sound coming from the monitors contains less of the troublesome muddy frequencies that contribute to the overall stage level we’re trying to reduce, while still allowing for the intelligibility required for good monitoring. As with all of these suggestions, this does require some discipline and sacrifice by the musicians/singers, as the monitor sound will be a bit thinner.

Probably the most impractical suggestion I’ll make, is also one of the most effective.
One of the main sources of stage mud is acoustic energy that comes from the back wall of the stage area (delayed). If at all possible, I suggest treating the rear stage-wall with acoustic absorptive material (the thicker the better). This will radically reduce the amount of acoustic energy bouncing off of the back wall (from drums, wedges, etc). I recommend using 2” thick acoustic-grade compressed fiberglass panels, from floor-to-ceiling on the rear (upstage) wall. Of course, an overall acoustic design is best left to professionals, but generally the rear stage wall is a good place to start.

A few other suggestions I’ll offer to generally help clean-up the sound:

• The use of noise gates on toms and kick drum.
• Baffles surrounding organ Leslie
• Positioning singers / choir away from band (opposing side of stage).
• Delay sound system to drums position (time alignment).
• Judicious use of high-pass filters (see my last article on high pass filter use).

Finally, good communication and cooperation is necessary by all involved when implementing any of these suggestions, with everyone working toward the common goal of providing the best sound possible for all in attendance. As with most things in life, there will be some personal sacrifice involved in contributing to the overall goal of presenting a clean, clear sound to your congregation…that’s why it’s called serving!

Happy mixing!

-Michael Grosso, senior audio tech – CCFL

This entry was posted on Thursday, August 6th, 2009 at 2:14 pm and is filed under Gearheads. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.