A Basic Live Sound Setup DiagramFebruary 27, 2009 6:00 am Live Sound
You know what they say about a picture and a thousand words. Well then, I have about two thousand words’ worth for you in this article!
I sometimes get e-mails from people who are uncertain about what components are part of a typical live sound setup, or exactly how to hook them up. Instead of trying to describe all the interconnections that are commonly involved, I decided to draw up a diagram (two, actually) of the setup that Rusty Strings, the band I run sound for, uses for their live shows.
OK, so here are the diagrams. The first one shows the interconnections made at the mixing or FOH (Front Of House) position between the mixer, the power amplifier, and the dual effects box. (Click on the diagram for a somewhat larger version on its own page.)
The second diagram shows the interconnections made to the instruments, microphones, and speakers onstage, at the other end of the snake. (Again, click on the diagram for a larger, printable “clean copy”.)
Fronting the House
These setup diagrams are fairly self-explanatory, but there are a few points I should clarify, beginning with the FOH (top) diagram above. We don’t use channel #5 in the snake because channel 5 in our mixer is broken. (You needn’t duplicate this practice!) Notice that the power amplifier is a dual-channel type. You may be used to thinking of dual-channel devices as handling the Left and Right signals from a stereo source. Here, we are instead using the two sections of the power amp (A and B) completely independently, with Section A used to power the main speakers via the mixer’s Main Out connection (we use only the left side of the mixer output, with all input channels panned full left). Section B of the power amp provides a completely separate mix to the monitor speakers.
The monitor mix is created by adjusting the Aux Send 1 controls on each mixer channel strip, essentially using them as an 8-channel mini-mixer (7 for us) to create the desired monitor mix at the Aux Send 1 output. Note that the output of the monitor side of the power amp (Section B) is routed to the stage via the snake (channel 9) rather than through a separate cable. See my article Mini-Tip: Send Monitor Signals On the Snake for more thoughts on this practice. We do use a separate cable from the power amp (Section A) to the main speakers since they will be drawing a lot of power.
The effects box is a dual unit with two inputs, which we feed from Aux Send 2 and Aux Send 3 (our mixer has four Aux Sends for each channel). We route the combined (mono) FX signal from the box back to the Aux Return input on the mixer. I have one side of the effects box set to a nice reverb and the other to a delay effect whose delay period can be set by tapping a front-panel button in time with the music - very cool! The amount of either effect applied to any given channel is controlled with the Aux Send 2 and Aux Send 3 knobs for that channel.
The snake itself has 12 cables in it: 8 terminate in XLR-type connectors and 4 in 1/4″ TRS-type “phone” connectors. We use 7 of the 8 XLR connections for microphone and instrument signals coming from the stage and one of the 1/4″ connections for the monitor signal going to the stage.
Taking the Stage
Turning to the onstage (bottom) diagram above, we see the connections that are made to the stage box (the stage end of the snake, literally a metal box with 12 connectors mounted on it). The monitor speakers are connected to channel 9 of the snake, as you see. The snake signal is routed into one speaker, then a separate cable takes it out of that speaker and over to the other one. The four vocal mics are connected directly to the stage box as shown. (We always use the same channels for everything because I have them marked that way on the mixer’s “scribble strip”.)
The two guitar amps have “Direct Out” connectors (XLR-type, conveniently) that we run directly to the stage box. One of the amps has a 1-10 level control, which I always set to “7″. The other outputs at a fixed level. Note especially the keyboard setup, which is a bit unusual. We have the keyboard set up so that its output is in mono, meaning that the Left and Right Output signals are the same. The Left-side signal is routed through a direct (DI) box and an XLR cable takes it from there to the stage box. The Right-side signal from the keyboard goes through a volume pedal to an onstage amp, which the keyboard player basically uses as a monitor. (The audience hears the keyboard mostly through the PA.)
Note: We use a DI box for the keyboard signal to convert the high-impedance keyboard output to low impedance. This allows the signal to reach the FOH mixer down 100 feet of snake without picking up hum or buzz, like it did the time we tried running the keyboard output directly to one of the 1/4″ connectors on the stage box.
The cable carrying the Main Speaker signal to the stage is routed to one of the main speakers as shown, then as with the monitors the output of this speaker is sent via separate cable to the other main speaker. (This means that both main speakers get the same signal, and both monitor speakers get the same signal.)
Well, I guess that’s about all the ’splainin’ I need to do. Some of the other articles in the “Live Sound” category discuss various aspects of this kind of setup in more detail. I will close with a couple of pictures of our semi-neat and tidy FOH setup at a typical Rusty Strings gig. The effects box and the (very heavy) power amp are mounted in a “portable” rack. The snake (100′) is wound on a cable reel I got at Lowe’s.