When I started my career in live sound many years ago, front fill was not much of a concern. Stage volumes were high (sometimes brutal), IEMs were for the rich and famous, and guitar amplifier simulators were a pipe dream. As a result, stage monitors (wedges and/or sidefills) were also really loud, and that meant you could count on them to bleed into the audience and fill in the vocals at seats close to the stage that weren’t covered by the PA system. You could also count on those monitors to create comb filtering that played havoc with your front of house mix, but that’s a discussion for another time.
Fast forward 40 years (ouch) and mixing live sound is a completely different animal. Stage volumes are generally much lower, most artists use IEMs instead of wedges, and even guitar amps are starting to disappear from the deck. The net result? You can no longer rely upon monitor spill to fill in audio for the first few rows of seats. In a lot of venues, those front rows are too close to the stage to be within coverage of the main PA, leaving patrons with an unsatisfying audio experience because they’ll hear some low-frequency and low-mid ‘wraparound’ from the PA boxes, but won’t hear any high-frequency definition. That’s where front fill speakers come into the picture.
Front fills are small speakers that sit on the downstage edge and are aimed at the first few rows of seats. It’s important that front fills are low-profile so that they don’t interfere with sightlines. This is particularly important in situations where an artist has family members seated in the front rows: you want to be absolutely sure that these folks can hear at least the vocals, if not the entire mix, and see the artist. There’s no need for these speakers to produce any significant bottom end; that will come from the main PA system.
The Details
Front fills will be physically closer to the audience than the main PA hang, so they’ll need to be delayed in order to time-align them to the main PA. If you don’t do that, then people in the front rows will perceive the main PA as being delayed. The delay time will be determined by how far the main hang is from the front fill speakers. In an ideal world, you’d have individual delay times for each front fill box but if you don’t have that luxury, measure the distance from one side of the hang to the center-most front fill and delay approximately 1 millisecond per foot. Most digital consoles will allow you to add this delay on any output bus.
Speaking of outputs, how do we route signal to the front fills? Simply choose a bus and soft-patch it to any available output. You have three basic choices as far as what bus(es) to use to feed the front fills: the main L/R mix, an aux send, or a matrix. Each approach has its advantages and disadvantages.
L/R Mix
Any digital console will allow you to route the L/R mix to multiple outputs. Send the L/R mix to a secondary output (or pair of outputs) and patch them to the front fills. You can even do this in mono, which is equally effective. Raise the volume level of the front fills until you can hear the clarity of the main mix but don’t make it so loud that you draw attention to it. As you’d expect, the people in the front rows will hear your L/R mix with the same balance that you hear out of the main PA (low end notwithstanding).
Aux Send
Given the fact that the stage might have guitar and bass amps as well as drums — but no monitors producing vocals — there may be a deficit of vocals in the front rows. You can use an aux bus to send only vocals into the front fills to compensate for this. The effectiveness of this approach depends to some extent on the stage volume of the instruments. If the instruments are loud, then the front rows will hear them clearly from the stage, so you can bring the vocals into the front fill until they overcome the stage volume. I typically route this send post-fader so that if I make any fader changes in the L/R mix, they’re reflected in the front fills as well, which is really important when you have more than one person singing lead vocal over the course of the show. You can also route a bit of guitar in there so that when you bring up the guitar channel(s) for a solo, the guitar will also get louder in the fill.
The disadvantage of using an aux send is that if you want to feed a lot of channels into the front fill, it starts to become a chore to create another mix just for the front fill. You can solve this by creating a post-fader send with all channel sends set to unity and feeding that send to the front fills. Why bother? Because you can increase the send level on channels that need more presence in the front fill (e.g. vocals) and decrease the level of channels that need less presence in the front fill because those sounds are also coming off the stage (e.g. guitars and drums, for example). This is too much work for my limited brain cells, so I have come up with another idea.
The Matrix
We all know the matrix as a mixer mixer (see Front of House, Nov. 2012 for the details), and I’ve found a sort of sneaky workaround that gives me the best of using an aux send and the L/R mix to feed the front fills.
First set up a matrix and patch it to the front fills. Delay the feed as described above. Feed the L/R mix into the matrix but don’t set it to unity. Instead, send it at 10 or 15 dB below unity (you’ll have to experiment). Then feed an aux send into the same matrix at unity (0 dB). Feed this aux send only from channels that need extra help in the front fills, typically vocals. This enables you to have the L/R mix in the front fills while giving you the ability to push the vocals forward.
The aux send should be post-fader so that when you ride a vocal fader, the level changes accordingly in the front fill mix. You’ll have to experiment with the balance between the L/R mix and the aux send in the matrix to find the right combination. If you push the L/R mix at unity, then you won’t be able to ‘favor’ the vocals in the front fill and they might get lost. Depending upon the stage volume of the guitar, I might also send a bit of the guitar channel(s) into the aux so that when there’s a solo, they get a little louder in the front fills as well. Use your time at sound check to sort this out.
Steve “Woody” La Cerra is the tour manager and Front of House engineer for Blue Öyster Cult, and Jon Anderson & The Band Geeks. He can be reached via email at [email protected].
