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Implementing front fills

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Dan Johnson:
I run sound for an independent Christian rock band.  We do a small number of local gigs and we travel some throughout the year.  We play a wide variety of venues from 100-200 seat church youth rooms to 6000 seat venues.  All the bigger events have major production provided and we bring our own sound for 95% of the smaller events.  While I fancy myself a decent BE, I'm certainly not very experienced as an SE.  I know how to make our system sound good but don't have much experience at all setting up any other systems.  I'm in the process of doing some minor upgrades to our current system.  I want to make sure I'm doing things right the first time instead of implementing something and then finding out later I've been doing it wrong (or missing some key element) all along.

I'm thinking about adding front fills to our system and I've never had to deal with this before.  It seems like every gig we do lately, a portion of the audience is standing right in front of the stage out of the coverage of the mains.  The other issue is when we play a big enough room that the speaker stacks are spread apart enough that I need a little more support (mainly vocals) in the first couple rows right in the center.  It seems like we are most often playing stages that are only 2' tall or it's the typical church stage where the entire front of the stage is steps from the floor to the stage which is roughly 4' above the floor.  

I'm wondering if I should be too concerned about the horn coverage pattern on the front fills or if it doesn't make that much difference.  I read through some old threads and saw recommendations for front fills with a wide variety of coverage patterns.  I don't want to create any cancellation because of overlapping patterns with the main speakers.  This wouldn't be much of an issue with a 2' tall stage with people standing right in front of the fills but maybe would be a problem in other situations.  

I was thinking of the possibility of using stage monitors for the front fill if I didn't need a tighter coverage pattern.  This would allow me to easily aim them up when we are on the short stage with people right in front of them.  I could make some wedges to aim them more straight out on a taller stage.  Is there any reason I'm not thinking of that this would be a bad idea?

The other thing I was wondering about was whether I should be worried about time alignment issues between the mains and front fills for the situations where the audience isn't standing right in front of the fills.  Any advice on this?  Any insight you guys can give is appreciated.

Tom Young:
First of all: these are very good questions. I applaud your observational and communication skills.

"I'm wondering if I should be too concerned about the horn coverage pattern on the front fills or if it doesn't make that much difference. I read through some old threads and saw recommendations for front fills with a wide variety of coverage patterns. I don't want to create any cancellation because of overlapping patterns with the main speakers. This wouldn't be much of an issue with a 2' tall stage with people standing right in front of the fills but maybe would be a problem in other situations."

There are a few things that are inherent with front fills:
They usually are not run as loud as the mains because they are so close to the target listeners. The acoustic energy from front fills is also usually absorbed by these folks (so the sound does not throw that far). And they are so small that the pattern control provided by the HF horn does not extend very far down in frequency. That being said; you do want fairly wide coverage which equates to a need for fewer front fill devices.

"I was thinking of the possibility of using stage monitors for the front fill if I didn't need a tighter coverage pattern. This would allow me to easily aim them up when we are on the short stage with people right in front of them. I could make some wedges to aim them more straight out on a taller stage. Is there any reason I'm not thinking of that this would be a bad idea?"

Not that I can think of (*). Most, if not all, "purpose-built" fill loudspeakers will have a smaller footprint but in your case the visibility of these fill devices is not as great an issue as it is in concert halls or may be in pristine/traditional style worship spaces. Using monitors (as you point out) allows you to aim them dead ahead or slightly upwards.... as needed. Many wedges can fire directly ahead without the need for an additional wedge/shim to prop them up. Plus you may need these extra wedges as back up for (monitor) wedge duty.

Actually, I can think of a few "gotcha's" to watch out for: You need to make sure that the wedges you use can be oriented so the wider coverage pattern is along the horizontal axis. Purpose-built front fills will provide 90-120 degree horizontal coverage. Wedges tend to be in the 60-90 degree range - no wider. So you may need 1-2 more wedges for front fill duty (in some venues) than you would if you had "real" front fills.

"The other thing I was wondering about was whether I should be worried about time alignment issues between the mains and front fills for the situations where the audience isn't standing right in front of the fills. Any advice on this? Any insight you guys can give is appreciated."

Yes - you should be concerned with alignment. Front fills will be out of alignment to the main FOH speakers (the LF energy from these will be covering in that front area even if the HF's are not) so the front fills will benefit by being delayed a bit. But they will also be out of alignment to the louder sources on stage (drums, loud wedges, etc) and the front row listeners are close enough that the energy from these on-stage sources will often be plenty audible. So if you apply a delay to the front fills you can align them (or get them closer to being aligned) to both of these later-arriving signals.

Front fills also need a high-pass filter because they cannot handle LF's as well as the larger main FOH ldspkrs. Plus you do not need to introduce more LF energy into that area, you already will have enough from the FOH. And they very definitley need equalization to smooth out their response. This is especially useful/necessary if the singers (or a pastor with a lav mic) lean over the front fills or walk out in front of them.

These days it is hard to buy a DSP that does not provide all of these processing functions. Take advantage of them.

Mike Caldwell:
If your board has an open post fade aux or a matrix mix that would be the best way to feed the front fills. You will be able to build a front fill mix independent of the main mix. The same thing goes for a rear delay fill mix as well.

Mike Caldwell

Rick Stansby:
I agree with Tom, especially the part about your very good understanding of what is necessary, and what pitfalls you might encounter.

I have regularly used monitors as front fills, especially when the band has IEMs, so the monitors are unused and the stage wash doesn't include much vocal.  Usually the monitor needs to be set on end, to get a wide horizontal coverage.  This can be an issue with sight-lines or a clean look.  

Wide coverage is your friend, so you don't need too many fills, and so the sound doesn't project too far.  When using more narrow boxes (70 to 90 degrees) I have put them at the outside corners of the stage (near the mains) facing in towards the center of the front few rows.  This will also solve the problem with delay, in the case that you don't have the processing available.

As has been mentioned you will mainly want vocals and quiet/non-amplified instruments in the front fills.  You probably realize that you won't need a bunch of drums, bass or electric guitar.  They are loud enough in the front row.

Lee Douglas:
Dan Johnson wrote on Sat, 13 December 2008 23:09


It seems like we are most often playing stages that are only 2' tall or it's the typical church stage where the entire front of the stage is steps from the floor to the stage which is roughly 4' above the floor.  




I don't know the answer, but it would seem to me that a front fill on a two foot stage with people crowded up against might have a usable sound for maybe four or five people crowded together across and possibly two deep with a wide dispersion pattern and nominally more for a four foot stage.  Something on the front light truss might have better coverage maybe?  Or would you just provide multiple fills across the front of the stage?

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