Announcement

Collapse
No announcement yet.

Power Line Noise

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Isn't one cause of amp hum that the circuit ground and chassis ground are the same? (the result of how the amp is internally wired and grounded).

    Comment


    • Kingrex
      Kingrex commented
      Editing a comment
      Tech or Atmasphere and others should have answers to your question. I have been assured under the right conditions I should be able to crawl down the throat of a horn and these amps be dead quiet.

    • Bill Hart
      Bill Hart commented
      Editing a comment
      More of an observation than a question (maybe a rhetorical one). In fact, the same issue arose for another user on another board, and we were discussing the internal grounding scheme of the amp as the culprit. Ralph was part of that discussion....
      As i recall, the solution in that case was to put everything on the same dedicated line, not something you'd want to do if you are using big, power hungry amps.

    • Tech7738
      Tech7738 commented
      Editing a comment
      The test procedure I've outlined will include amplifier internal grounding issues. The first test is the amp powered, not connected to any input, inputs shorted, physically not in the system. If the amp is not meeting specs that way, it has an internal issue.

      Putting everything on one circuit isn't usa problem even with high power amps up to 1kW because the high power demands are produced only during peaks, and the load reflected back to the power line is smoothed by the amps power supply, in other words, not directly reflected instantaneously on the line, though that depends on the design of the amps power supply. The main problem with high power amps, several of them, all on the same circuit is the possibly high in-rush current at turn-on. I had a rack full of 1500W commercial amps trip a 20A breaker at start up, so we sequenced their turn-on, problem solved. Actual music never came close to a breaker trip.

  • #32
    I was playing with the REW software and when I started it today it was saying I cant have the Sound Card and Mic calibration files as the same.
    Under the Soundcard tab I have the input set to my Mic calibration file.
    Under the Mic/Meter tab I have the button for Mic or Z weighted SPL meter checked. If I apply my mic calibration file I believe I get the error. If I leave it as None, the SPL meter runs as red numbers.

    Can you help me understand what I am to check. I am just trying to do SPL test in my room to see what listening volumes and room noise I have.
    Thanks
    PAP Trio 10/Voxativ & PAP Trio 15 Horn speakers, Ampsandsound Casablanca monoblocks, First Sound Audio Mark 3SI preamp,
    Mojo Audio Deja Vu server, Mojo Audio Mystique V3 DAC, The Linear Solution Ethernet Switch, Blue Jeans Ethernet cablling,
    Akiko Corelli, Custom power strip direct wired to panel with OFC copper wire. Inakustik Ref Air 2404 Speaker cable. Genesis and Inakustik NF2404 Air Interconnects.

    Comment


    • #33
      Originally posted by Kingrex View Post
      I was playing with the REW software and when I started it today it was saying I cant have the Sound Card and Mic calibration files as the same.
      Under the Soundcard tab I have the input set to my Mic calibration file.
      Under the Mic/Meter tab I have the button for Mic or Z weighted SPL meter checked. If I apply my mic calibration file I believe I get the error. If I leave it as None, the SPL meter runs as red numbers.

      Can you help me understand what I am to check. I am just trying to do SPL test in my room to see what listening volumes and room noise I have.
      Thanks
      You should just use the mic cal file, point to it in the Mic/Meter tab, no sound card cal is necessary, just clear it. You might have to restart REW. Red SPL meter readings indicates it's out of calibration.

      If you leave the Umik plugged in and restart REW I think it should be fine. If it asks for the mic cal file again, point it to the file. Don't cal the sound card. If it asks for a soundcard cal file, skip that, go to soundcard preferences page and clear anything in the cal file field.

      Don't use Z weighting for acoustic noise measurement, it will read too high. Use A for low level noise measurements. Slow response is better for noise measurements. Using the h

      SPL figures from 30-60dBA is normal for room noise. Anything red indicates a system overload or calibration problem of some kind.

      Comment

      Working...
      X