Run speakers through snake returns???

Walter McNeil

New member
Dec 17, 2018
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50
Utopia TX
Hi All,
I'm a complete novice taking over the technology in a small rural church. The audio installation has been in place for >10yr and I'm trying to fix/upgrade it.
We've got a 16 channel XLR snake (with 4 XLR returns) under the floor.
The 750Wx2 power amp is at FOH with the mixing board, and it is powering the passive speakers THROUGH THE AUDIO SNAKE. The amp is hooked up to returns A,B,C. So apparently both speaker negatives share a single return channel.
The returns don't appear to be a thicker gauge than the 16 sends. I've done enough googling to know this is not a good practice, but people tell me that this system was set up by a professional at considerable cost.
The system gets plenty loud for our purposes; it's a small church and we don't need it loud. And sounds pretty good. How fast should I be rushing to move the amp up to the stage? I might be able to move it up on the stage into a cabinet where the snake's stagebox resides, but getting power there might be a hassle.
Or is this a case where if it ain't broke don't fix it?
Thanks,
Walt
 

Douglas R. Allen

Sophomore
Jan 11, 2011
215
0
16
Maine USA
I wouldn't do it. Part of the equation is the impedance of the cable. How this is loading the amp I can't say but it can't be good. If your happy with the amp at the mixer and its not too far from the speakers, say 50 feet or so then 16 gauge speaker cable wire should do as a replacement. If its much farther then your going to need much thicker wire. Besides the loading using "snake microphone" cable there is the power loss involved. Figure the total distance from the amp to the speaker that is the greatest distance away and google the speaker cable recommended for the wattage/impedance you have. There is what is called "powered snakes" that have speaker cable in them. Before I'd go that route I'd just run some speaker cables from the desk or as you say put the amp on stage.
 

Tim McCulloch

Graduate Student
Jan 11, 2011
2,893
24
38
Wichita KS USA
Not with that snake, no. Too much wire resistance and the shielding can cause problems, too.

The "returns" are there to do exactly what you describe - connect the mixer's outputs to amplifier inputs near the stagebox.

Normally I'd suggest doing it "right" but in this instance, if it ain't broke, don't fix it.
 
I'd look at changing that configuration soon, having seen snakes damaged by it in the past. You've got an amplifier capable of pushing ~80V at ~10A (assuming an 8 ohm load) through I'm guessing 100+' of what's likely 24 AWG wire. Even ignoring the additional resistance (which isn't likely to harm your amplifier, but also isn't helping the power get delivered to the loudspeakers), the 24AWG wire is only good for ~3A max. If you assume that the amplifier is a voltage source, and take into account the resistance of 200' of 24AWG wire (100' round trip), the current output from the amplifier drops to ~6A, and you are burning up ~175W in the snake (and only delivering ~280W to your speakers, max).

I'm guessing the only reason you haven't had an issue yet is because you aren't running things continuously at max output.
 

Walter McNeil

New member
Dec 17, 2018
4
0
1
50
Utopia TX
Thanks all. We found some power under a cabinet up on the stage and moved the amp. Turned out to be MUCH simpler than I figured it would be.
Still scratching my head to figure out why the 'professional' would have configured it that way. The snake terminates in a stage box inside a big cabinet to one side of the stage, that's also where the speaker cables terminate and there is power in the box.
So I can't figure out why they would put the power amp back at the mixing console.