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How low can voltage be at amp?

Discussion in 'Live Sound [BG]' started by Guapotims123, Nov 29, 2018.

  1. Guapotims123


    Jun 19, 2012
    I think we have a problem with low voltage at our practice house. I will bring my voltmeter (VOM) and check it next practice. We are plugged into a 20 amp 110 v receptacle with a brick type power conditioner of unknown history. We are running 2 solid state small guitar amps (25 to 50 watts) and a 500 watt Rumble bass head along with a board with 2 500watt amps and a sub amp of about 1000 watts (guessing) I know this is too much for a single 20 amp circuit, but the only other choice we have is to run long extension cords. Any help would be appreciated.
  2. Guapotims123


    Jun 19, 2012
    Not really worried about blowing the breaker. Low Voltage is an amp killer. Most amps will begin overheating or quit all together in a low voltage or "voltage drop" setting. I love my amp and need to know how much (or little) is dangerous for it. We've experienced some problems like this during practice but didn't know what was causing it (thinking it was faulty equipment)
  3. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    That's not too much for the circuit at all. So you aren't dealing with current issues.

    As for voltage, you're on the right track. Check it with your volt meter next time you are there.

    Now, to the issues of what is "too low", I Googled up the manual for your amp. Here's the only thing I found about voltage.

    "IEC POWER CORD SOCKET — Connect the included power cord to a grounded A/C electrical outlet in accordance with the voltage and frequency ratings specified on the rear panel of your amplifier."

    So...… it appears that the answer to your question is on the back of your amp.

    To that end, here's a pic of the back of the Rumble 500 head. And there's your answer just below the power cord socket.

    "100-120V ~ 50/60 Hz"

    Guapotims123 likes this.
  4. play4sanity


    Mar 5, 2012
    Raleigh, NC
    The low end of the range is probably targeting sales in Japan. It will probably run down to ~90-ish V or so. Just understand that the power stays the same for Class D amps so the current goes up as the voltage goes down. The math: 950W / 120V = 7.92A, 950W / 90V = 10.56A. 950W is a maximum number. Actually power draw will depend on how loud you turn it up. And yes, too low a voltage (like at the end of a long extension cord) can be a killer. Good luck!
    Guapotims123 likes this.
  5. Guapotims123


    Jun 19, 2012
  6. Guapotims123


    Jun 19, 2012
    Hey thanks! I didn't even think to look at the back panel. :)
    two fingers likes this.

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