Way back in the August 2022 issue of FRONT of HOUSE, we talked about the way life on stage changes when your band switches from wedge monitors to IEMs. We also mentioned that switching to IEMs can change the FOH mix. This month, we’ll take a closer look at what’s happening (or not) in the house when your artist makes the switch.
The Bleeding has Stopped
One of the big problems with loud stages is that the volume levels between instruments and monitors can become an “arms race.” We’ve all experienced this: you make a lead vocal wedge louder, and other musicians are affected because they now hear that wedge in addition to their own wedge mix. They, in turn, want their wedge louder, and the dominoes start to fall. When an entire band switches to IEMs, that monitor “crosstalk” can be eliminated, which is mostly a good thing. You won’t have issues with one performer hearing another performer’s mix (unless the band is using a combination of wedges and IEMs on stage — which is itself a topic for another time). It becomes possible to reduce the overall stage volume and to also eliminate bleed from vocal monitors into the house.
On one hand, this increases clarity in the FOH mix because you avoid the phase issues and comb filtering caused by monitor leakage interfering with the house P.A. system. On the other hand, it also means that you can’t rely upon monitor spill to make vocals audible for people who are sitting or standing close to the stage. Those patrons are probably not covered very well by the main P.A. system (if they were, you’d have feedback issues), and as they’re close to the stage, instruments like acoustic drums and bass amps may be raging in their faces.
The fix for this is relatively simple: add a front- or down-fill at the downstage edge and feed instruments into the fill as needed. A front fill works fine in many venues if you simply use an aux send to route vocals to the fill, but in other venues — particularly when the venue is wide and the center seats are far from the main P.A. hang — you’ll need to route the entire mix into the fill. As the fills are physically closer to the up-front folks, sound from the fill will arrive at their ears well before they hear sound from the main P.A., so the fill will need to be delayed. Use a starting point of around 1 mS per foot of distance between the main hang and the fill speaker(s). Fortunately, most digital desks or system processors provide a delay on every output, making this relatively easy to accomplish.
Delaying a fill can be trickier if the entire stereo mix is being sent to the fill, because delaying the L/R outputs will delay them in both the main P.A. and the fills. Instead, feed the L/R mix into a matrix (which usually has its own delay) and use the matrix to feed the fills with a delay that aligns them to the main P.A.
No More Texas Headphones
Another good thing that happens to the FOH mix when a band switches to IEMs is that there will no longer be stage monitors blowing into microphones. On the obvious side, that means little-to-no-chance of feedback. On the not-so-obvious side, it means that your drum mics no longer pick up all that bleed like they did when the drummer had a pair of “Texas Headphones” for monitors (i.e., — large drum fill speakers on either side of their head). Ditto for the overheads, and most of the mics on the stage. This gives the FOH engineer more control over the FOH mix, while reducing phase issues.
A Cymbal of My Affection
When stage wedges are eliminated, cymbal leakage into the lead vocal microphone becomes much more apparent because this “noise” was masked by the din coming from the wedges. As a result, you may need to educate the vocalists on mic technique, encouraging them to stay close and on-axis to their mics as much as possible. If they tend to back away from their vocal mic, cymbals can bleed in, not only changing the timbre and volume of the cymbals but possibly adding effects to them. Stewart Copeland’s high-hat delay notwithstanding, you probably don’t want those kinds of effects on cymbals.
Adding to this problem is compression that’s applied to the lead vocal channel. Setting the compression threshold so that the ‘comp kicks in when the singer is at medium to loud levels will give you the desired gain reduction. But when they stop singing, there’s no more gain reduction and background noise appears to get louder. Cymbals love this. A lead vocalist walks away from the mic, the compressor lets go, and your carefully crafted FOH mix becomes awash in cymbals. Possible remedies for treating this problem include manually muting channels when necessary, patching an expander on the channel (which hasn’t worked very well for me), and carefully dialing in a low-pass filter. Depending upon the vocalist, an LPF with a cutoff around 8 or 9 kHz can help reduce cymbal bleed without making the vocal sound dull.
Options for switching a microphone on or off include mute switches such as the HotShot DM1 or HotShot 48V from Radial Engineering. These footswitch-operated boxes intended for use by musicians silently switch a microphone between two outputs. If only one output is used, the devices function as a mute switch. An added bonus is that when using the second output, the mic can be switched between (e.g.,) the front-of-house desk and a separate monitor channel, enabling it to be used as a talkback mic. Very clever.
Another option for muting microphones is the OPTOGATE. This clever little guy connects in between a microphone and cable and uses an infrared sensor to detect if someone is in front of the mic. If so, the device turns on the mic; if not, the mic is muted. There are a couple of different models available, but the OPTOGATE is probably best used when the microphone will be stand-mounted, and not handheld.
One more thing to be aware of when your band switches to IEMs is that the musicians will probably be more sensitive to low- and low-mid frequencies from the house P.A. “Wrap-around” from the FOH speakers can cause low-mids to build up on stage and can mess with an artist’s perception of timing because the wrap-around is late relative to their in-ear mix. This is compounded by the fact that earpieces tend to lose some of their isolation at lower frequencies. The best way to alleviate this issue is to make sure the P.A. is properly deployed, but sometimes notching out a few dB in the region around 400 Hz helps. Also, the performers may ask you to dial back the subs if the subs are under the stage, where the LF energy can overwhelm their IEM mixes.
Steve “Woody” La Cerra is the tour manager and front of house engineer for Blue Öyster Cult.
