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[Derrick McDonald]

I've been having this problem recently and can't seem to figure out the problem/solution.  I'm getting distortion in the mains whenever we push the system slightly hard (normal rock levels, not clipping channel strips, board or dsp or amps) and I noticed whenever this happens that the power light on the Furman flickers.  Now, the only thing plugged into the Furman was the DSP, so I bi-passed that and plugged the DSP into a circuit.  Same problem.  This particular Furman does not have a meter showing the voltage.

I have three 20amp circuits dedicated for power.  Tops (2-macrotech 2400) on one, Subs (macrotech 3600) on another and monitors (1-macrotech 2400, 2-macrotech 1200) on the third.  Could a sudden drop in voltage as a result of power draw from other circuits be the culprit?  Maybe the bar's circuits are carrying too much right now?  They just installed a new Neon marquee above the bar, perhaps the electricians tied in incorrectly?

I do have a Furman at FOH that has voltage metering, should I hook that up to those circuits and drive the system to see if it drops? 

Any ideas?

[Tim Perry]

I've been having this problem recently and can't seem to figure out the problem/solution.  I'm getting distortion in the mains whenever we push the system slightly hard (normal rock levels, not clipping channel strips, board or dsp or amps) and I noticed whenever this happens that the power light on the Furman flickers.  Now, the only thing plugged into the Furman was the DSP, so I bi-passed that and plugged the DSP into a circuit.  Same problem.  This particular Furman does not have a meter showing the voltage.

I have three 20amp circuits dedicated for power.  Tops (2-macrotech 2400) on one, Subs (macrotech 3600) on another and monitors (1-macrotech 2400, 2-macrotech 1200) on the third.  Could a sudden drop in voltage as a result of power draw from other circuits be the culprit?  Maybe the bar's circuits are carrying too much right now?  They just installed a new Neon marquee above the bar, perhaps the electricians tied in incorrectly?

I do have a Furman at FOH that has voltage metering, should I hook that up to those circuits and drive the system to see if it drops? 

Any ideas?

What size are you cords into the outlets? how long are they? if they are 100" or longer is the excess coiled up?

[Derrick McDonald]

What size are you cords into the outlets? how long are they? if they are 100" or longer is the excess coiled up?

They vary in length and width, but they're whatever gauge Crown supplies them with.  Some cables are coiled up, maybe one or two turns.  I'd say the longest cable isn't longer than 3'.

[Mac Kerr]

They vary in length and width, but they're whatever gauge Crown supplies them with.  Some cables are coiled up, maybe one or two turns.  I'd say the longest cable isn't longer than 3'.

Tim meant the cable from your amps to the 20A circuits. The voltage drop could very easily be happening in those cables if they are either long, or too small a wire gauge. The length of wire between your amps and the service panel should also be considered.

Mac

[Derrick McDonald]

Tim meant the cable from your amps to the 20A circuits. The voltage drop could very easily be happening in those cables if they are either long, or too small a wire gauge. The length of wire between your amps and the service panel should also be considered.

Mac

Ah, yes.  They've gotta be more than 100' however I do not know the gauge off hand. I would assume they'd have to be at least 12 to handle 20-25 amp circuits. 

[Mac Kerr]

Ah, yes.  They've gotta be more than 100' however I do not know the gauge off hand. I would assume they'd have to be at least 12 to handle 20-25 amp circuits.

If the total circuit length is 200', 100' of your cable, 100' in the wall, this calculator says you should have #8 guage wire to keep voltage drop to less than 3% with a real 20A draw. I think we can assume neither you nor the venue have cable this heavy.

Next time you are in that situation, have someone watch a voltmeter that is reading the voltage at your amp racks to see how much drop you are getting. The meter in the Furman is not likely to be accurate, none of the ones I have measured were, but they do give you a good indication that you are getting voltage drop as you watch them fluctuate with sound level.

Mac

[Derrick McDonald]

I'll try that.  If it is a voltage drop, what are my courses of action?

[Tim Perry]

Ah, yes.  They've gotta be more than 100' however I do not know the gauge off hand. I would assume they'd have to be at least 12 to handle 20-25 amp circuits.

We can get into a lot of trouble by making assumptions. 

I have been to a number of event lately where the client says "ill supply you with power" and it is several 16 GA orange cords in series... I just politely say Id prefer to use my own and unroll the 10 GA SOOW.

[TJ (Tom) Cornish]

I'll try that.  If it is a voltage drop, what are my courses of action?

It's clearly voltage drop if your meter is showing it.  What can you do about it?  Shorten your supply cables, increase wire size, have an electrician come in and re-torque all the distribution components, install a subpanel near where your amps live fed by real wire, and/or turn down the volume.

[David Parker]

I've been having this problem recently and can't seem to figure out the problem/solution.  I'm getting distortion in the mains whenever we push the system slightly hard (normal rock levels, not clipping channel strips, board or dsp or amps) and I noticed whenever this happens that the power light on the Furman flickers.  Now, the only thing plugged into the Furman was the DSP, so I bi-passed that and plugged the DSP into a circuit.  Same problem.  This particular Furman does not have a meter showing the voltage.

I have three 20amp circuits dedicated for power.  Tops (2-macrotech 2400) on one, Subs (macrotech 3600) on another and monitors (1-macrotech 2400, 2-macrotech 1200) on the third.  Could a sudden drop in voltage as a result of power draw from other circuits be the culprit?  Maybe the bar's circuits are carrying too much right now?  They just installed a new Neon marquee above the bar, perhaps the electricians tied in incorrectly?

I do have a Furman at FOH that has voltage metering, should I hook that up to those circuits and drive the system to see if it drops? 

Any ideas?

are you sure you actually have 3 circuits. 3 wall outlets could easily all be on the same circuit. Forgive me if you have already checked this out.

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