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Rattling REL problem

Discussion in 'Subwoofers' started by Shaka, May 12, 2005.

  1. Shaka

    Shaka
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    I have a REL Q150e mkII which I got about 8 months ago. I'm experiencing a problem with it but I'm not sure if it's a genuine fault or the limitations of the sub.
    The problem is that at certain frequencies it starts to rattle!! This has been like so since I got it which is why I keep thinking it's not a technical fault. The first couple of months I thought it was something else in the room that was rattling but when I put my head next to it I realised it was the actual sub.
    I've been putting up with it because it only happens for certain effects (I guess very low frequencies) where the effect lasts for more than 1 second. A good example is near the opening credits of The Fifth Element, before the spaceship comes into view, there is a nice low rumbling sound as you hear it approaching, but as soon as it comes into view, the sound goes even lower and that's when the sub starts to rattle.

    I have it connected to an AVR300 with the crossover on the amp set to 70Hz and the volume on the sub at around 40%. The mode switch is at 2 (LFE/0 degrees phase/crossover bypassed for LFE). The Slam/Depth switch is at Depth.
    I'm also using the high-level input connection and the hi-level volume is again at 40% and roll-off set at around 40Hz.
    So the settings are quite modest, not too high. I even experimented with turning the low-level volume all the way down (during the Fifth Element scene) but it still kept rattling :(.

    Do you think it's a fault or my settings, or is it cause the sub can't cope with the very low frequencies?
     
  2. Weidass

    Weidass
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    not meaning to ask silly questions, but are you sure its not a blowing (hissing/distortion) sound instead of a rattling sound? only reason i ask is on one of my old subs (not an rel) the remote control IR reciever on the front of the sub wasnt sealed properly and when it played low it sounded like rattling, even though it was actually blowing.
    all it needed was a covering of sellotape and all was well.
     
  3. JBL 4645

    JBL 4645
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    all it needed was a covering of sellotape and all was well.[/QUOTE]

    He maybe right, I’ll play some spot frequencies at 20Hz to around 120Hz for the sub bass and play them at different sound pressure levels to see if there is any rattling other than the sub bass it self, if the sub bass is leaking air due to low frequencies down to around 18Hz to 40Hz that’s an approx please check it out with those sine wave tones

    Hear is a list of some sine waves.

    http://www.snapbug.ws/sinewaves/


    Play it from the pc into the AVR plug into the aux at the front of your AVR by using a long rca phone jack to rca phones, and set the volume at a low level on your pc and the AVR turn it down to -30db.

    Play the tones from 18Hz to 120Hz which is the cut off point on most Dolby and dts film soundtracks, use caution when paying this, start at the lowest !8Hz and go though right up to 120Hz using the SPL meter and taking notes as you go along step by step.

    Now go though it again and raise the master fader on the AVR by 2db each time, as you go along with the testing.

    You should locate the problem within a short time, also when the problem is corrected you can use the tones for other alignments and testing.

    Good luck, and remember use caution as this can damage the loudspeakers, and sub bass, nothing is indestructible. :)
     
  4. Crustyloafer

    Crustyloafer
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    I would check all of the allen bolts that fix the drive unit to the cabinet, I have experienced this with a Q400 that had loose drive unit fixings. Also check all of the fixings that hold the amp module to the cabinet too.
     
  5. Shaka

    Shaka
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    (forgive any misspelling, been to the pub for an afternoon drink :) )

    Thanks for the info, I'll try tonight. Weidass - yes it's definitely a rattling noise but it could be caused by similar reasons to what you described.
    To bve honest I did supect something loose on the sub or a small rip on the driver and the unit, but thought that's not possible as the sub is brand new.

    I don't mind tightening up any loose nuts or bolts but if it's a tear or something else which I have to fix by using sellotape or blutacj or something then should I just get it exchanged as it's still under warranty?

    Shaka
     
  6. Shaka

    Shaka
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    Well I've had a quick look around the sub and experimented a bit more. Everything is nice and secure. All the bolts holding the driver to the unit are nice and secure as expected. The foam ring around the driver is glued on properly, there are no tears or cuts on the driver. The bolts at the back of the unit are all perfectly secure so there is nothing loose at all.
    I ran the Fifth Element scene again several times and it seems to be the motion of the driver moving in and out that makes the rattle. During this scene, it really is moving in and out quite a distance and I think it's either hitting something inside the unit on the way back or it's hitting the unit opening on the way out.
    This seems to be unaffected by the volume level setting on the sub. I had it turned all the way down and it was still rattles at the frequency.
    Any ideas? Is it faulty?
     
  7. alexs2

    alexs2
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    What you described sounded very like the driver hitting it's end stops so to speak,but since you say it is also independent of volume,it's very possible that the driver has been damaged initially,and does indeed have a part loose now....if it's under warranty,REL may be able to help you.
     
  8. b33k34

    b33k34
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    I was testing a few subs at the weekend and experienced something very similar on a Monitor Audio R360 using the track Papua New Guinea by Future Sound of London. Other stuff put through the sub was fine at much higher volumes but the bass on the intro to FSOL caused almost a 'rattle' from the sub.

    Shop staff were at a bit of a loss and just turned it down further (it was only at 12'o clock)
     
  9. Timbo21

    Timbo21
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    Oh, I rember it well :clap:
     
  10. ttree sound

    ttree sound
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    "I'm also using the high-level input connection and the hi-level volume is again at 40% and roll-off set at around 40Hz"



    Shaka, sound content within a film will still drop pretty low even if the LFE channel is not being used, so I think what your hearing is the very low frequency sound going to your font speakers and sub (high level). Check that its not your front stereo pair thats making the noise. If you send a very low frequency signal to a sub the driver will sound as if its vibrating but no sound is heard, either its below what the sub can produce or its below what you can perceive as sound.
     

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