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Thread: Motorboating on TT

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    Senior Member quindecima's Avatar
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    Angry Motorboating on TT

    Here is a little problem I am trying to resolve. When I changed to my 4351's I moved them to the other side of the room. My son and I moved my entire audio stack by slipping some slick coasters underneath and pushing it from the bottom so very little was disconnected. I decided to play some of my vinyl and when I turned the volume up the woofs started to motorboat, needless to say I shut it down and tried to figure out the problem, so far it has escaped me. The stereo works fine on tuner and CD but not the Technics SL1200 which BTW always worked fine before. Anybody have any ideas?

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    My take;

    ( For whatever reason / & I wouldn't over-think why it's so ) but it seems you now have more LF feedback than before .

    I'd suggest that you need to better ( mechanically ) isolate that turn-table from the low frequencies in your system .

    Foam can work wonders ( & so can elastic band slings / a la, the great DJ's of the past ) .

    Either Google for more suggestions or wait for others to supply answers from their own experience .


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    Senior Member quindecima's Avatar
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    I tried 2in. of insulation foam to no avail. If I lift up on the TT sides from the bottom it stops. Beats me, I don't want to lose the use of my TT, I have a lot of vinyl I listen to.

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    Click the pic:




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    Senior Member edgewound's Avatar
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    Quote Originally Posted by quindecima View Post
    Here is a little problem I am trying to resolve. When I changed to my 4351's I moved them to the other side of the room. My son and I moved my entire audio stack by slipping some slick coasters underneath and pushing it from the bottom so very little was disconnected. I decided to play some of my vinyl and when I turned the volume up the woofs started to motorboat, needless to say I shut it down and tried to figure out the problem, so far it has escaped me. The stereo works fine on tuner and CD but not the Technics SL1200 which BTW always worked fine before. Anybody have any ideas?
    TT cartridge might be picking up a standing wave in the room. Try moving the TT or try some bass traps or other wall treatment to soak it up.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    You can get tonearm/cartridge compliance resonances that'll cause woofer pumping without feedback from the speakers.

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    Quote Originally Posted by Earl K View Post
    My take;

    ( For whatever reason / & I wouldn't over-think why it's so ) but it seems you now have more LF feedback than before .

    I'd suggest that you need to better ( mechanically ) isolate that turn-table from the low frequencies in your system .

    Foam can work wonders ( & so can elastic band slings / a la, the great DJ's of the past ) .

    Either Google for more suggestions or wait for others to supply answers from their own experience .

    Showing my age here, but people forget the problems we always had dealing with bass in the days of vinyl. Marantz and Luxman preamps had variable filters to cut the bass to avoid problems related to bass (Marantz 7 was 30 & 100 Hz). It's physics so anything you can do to "de-tune" the spring-mass system will work. Increasing the mass of the TT can help as well - this is how the old Empire Troubadore approached the problem. Is it the arm or the TT itself . . . it's a system. Not always obvious. Or just use a filter - it may not take much.

    P.S. When you changed the position of your (heavy) system on the floor, you changed the "tuning" of the overall system as well - the floor can now "tune" at a different frequency - the system has changed. How stiff is the floor? Etc.

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    Senior Member SEAWOLF97's Avatar
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    It's been a while since I had that problem, but I remember the symptoms
    of feedback more as "howling" than "motorboating".

    The positioning necessitates my living room TT to be not too
    far from the speakers. Putting a slab of marble under the TT helped in my case.

    Many older preamps have a "rumble filter" that helps. Never could solve the problem on certain records when using the AR3's.
    “If you think that’s the dumbest thing you’ve ever heard,
    just wait a couple minutes!”

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    Senior Member Don C's Avatar
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    I think you have an RCA plug that's not fully inserted. Push them in while twisting. Double check all connections.

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    Quote Originally Posted by quindecima View Post
    Here is a little problem I am trying to resolve. When I changed to my 4351's I moved them to the other side of the room. My son and I moved my entire audio stack by slipping some slick coasters underneath and pushing it from the bottom so very little was disconnected. I decided to play some of my vinyl and when I turned the volume up the woofs started to motorboat, needless to say I shut it down and tried to figure out the problem, so far it has escaped me. The stereo works fine on tuner and CD but not the Technics SL1200 which BTW always worked fine before. Anybody have any ideas?
    Woofer pumping is was and always will be a very common problem with Lp playback
    So much so that most receivers and amps from back in the day had a sub sonic filter button or switch
    If you have one try it that's why it's there
    Also try playing the record with the dust cover on and down if you have one of those too
    If the table is in a really bad spot just the compound of the vinyl or a super small warp or wave in a record can induce the same pumping
    Actually if your gain is high enough a blank disc will do it
    Nothing is wrong you just need to do some adjusting

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    Quote Originally Posted by edgewound View Post
    TT cartridge might be picking up a standing wave in the room. Try moving the TT or try some bass traps or other wall treatment to soak it up.
    I missed this
    Exactly
    Or just try closing the lid first

  12. #12
    Senior Member Lee in Montreal's Avatar
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    Hi Quindecima

    I suggest you first determine what causes the rumble. If it is the body of the turntable that picks-up low frequencies, or if it is coming from the floor or your installation on which the turntable is fitted. also, at what sound level do you get that nasty rumble?

    Also, when you get these nasty LF feedbacks, did you notice if the cartridge/stylus was moving (up and down) a lot?

  13. #13
    Senior Member quindecima's Avatar
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    The last time I tried an LP I noticed that the tone arm was moving up and down a small amount. I don't know where else I can move it. Here are pics of my current setup.
    Attached Images Attached Images   

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    Senior Member Lee in Montreal's Avatar
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    The turntable is located right by the cabinet. Either the structure/rack is picking the vibrations, or perhaps it is the body of the turntable. Most likely moving the rack away from the speakers will solve the problem. ;-)

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    Senior Member hsosdrum's Avatar
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    You gotta get that TT out of the corner. Large amounts of bass energy build-up in room corners. Just put your head into the corner near your TT the next time you're playing music through the system and you'll hear just how much. Walk the room next to the walls while playing music to find the spot with the biggest bass null (the most bass cancellation). Put the TT there.

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