motorboating

Discussion in 'General Electronics Chat' started by t-bone, Apr 4, 2008.

  1. t-bone

    Thread Starter New Member

    Apr 4, 2008
    3
    0
    could some one explain what motor boating is?
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Generally means an oscillation, or instability condition.

    Steve

    p.s.- there are some non-technical explanations which are pretty funny, but I'll leave them out
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    It is a very slow oscillation in an audio circuit so it makes a sound like a mororboat. Putt, putt, putt etc.
     
  4. Xray

    Well-Known Member

    Nov 21, 2004
    58
    1
    It is exactly as Audioguru described, and it is quite often caused by a weak or totally open electrolytic filter capacitor in the power supply. When the filter caps aren't doing their job, this can sometimes allow audio signals from the output stage to feed back to the low-level input stages, causing a low-frequency "motor-boat" sound in the speakers.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    It's most often associated with vacuum tube circuits. I had an amp that had that problem, and was temporarily cured by a new 12AT7. I got an Archer lifetime tube and just swapped a new one in every two weeks or so.
     
  6. MusicTech

    Active Member

    Apr 4, 2008
    144
    0
    I have played with this, when you get a chance, get a good sound generator (if you use mac, I believe the website is like hitsquad.com, something like that, you can google it) and look for signal scope pro, it has a decent free trial. Use the square wave setting at like .5 Hz and you will really here the putt. If you use windows, I'm sorry, but I don't have any software suggestions
     
  7. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Also, according to a friend of mine, motor boating can be caused by having AC out of phase, since it will provide positive feedback instead of negative..

    Steve
     
  8. Xray

    Well-Known Member

    Nov 21, 2004
    58
    1
    That's a new one by me! I've heard of AC phasing causing hum, but not motorboating. :confused:
     
  9. Xray

    Well-Known Member

    Nov 21, 2004
    58
    1
    On second thought.... are you speaking of AC power Mains phasing? Or are you referring to some other type of phasing such as speakers, audio transformers, etc???
     
  10. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    No, the mains transformer, it is driving a tube amplifier of some sort..

    Steve
     
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