Sub-frequencies in vinyl?

Discussion in 'Miscellaneous [BG]' started by Electricblue, Dec 5, 2013.

  1. Electricblue


    Feb 1, 2011
    So I obtained some Toots & the Maytals mp3's from a trusted, legal and fully legitimate website, I think they were taken from vinyl originally.

    On a few of the tracks, there is a frequency (looks like about 1hz) that causes my hifi speakers to center, then pull back into the basket, and center again all the way through the tracks. This is obviously from a warped record. Question is, will this damage anything?

    My amplifier has a lot of current capability (+/- 30A per side in the manual) so whatever you feed into it, you will get out of it. I don't want to damage my speakers or strain the amp for no reason. I don't have a Subsonic switch on any of my Hifi stuff.

    At listening levels, the speakers don't look like they're at the end of their travel, but there's probably a good 3-5mm excursion inwards at this frequency if that makes sense.

    Amp: Harman/Kardon HK610
    Speakers: Wharfedale 510.2 mk2

    Thanks :bassist:
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  3. Garyth

    Garyth Now What ..?

    Sep 9, 2013
    Punta Gorda Florida
    if it doesn't bottom/full extend and the signal isn't too much for the speaker, there's no way for damage. I've seen burned coils and popped cones from over-extension but the source had to get it there.
  4. Electricblue


    Feb 1, 2011
    Thanks for the reply. That's what I thought, but surely there is a lot of power going into the speaker to make this frequency? Because this frequency is combined with the music signal (being bass heavy reggae), maybe a bass pulse would push the cone a bit too far backwards?

    I'm paranoid about this kinda thing, I just don't wanna overheat the coils either...
  5. Hi.

    If You can't get clean tracks, get a HPF.

    Everyone who listened vinyls with less than perfect turntables had those for that exact reason.

    A HPF set to 15Hz or thereabouts, won't rob anything from the listening experience, but it will protect the speakers.

    Uncontrollable low frequency oscillations will fry voice coils pretty fast since the cooling capacity of the motor structure is pretty much 0 on sub 10Hz frequencies.
    It just hasn't been designed for that in mind.

    No sense in wasting all that power conversion capability of the amp either, and quite probably increasing the distortion all across the frequency range.

    IMO anyway.

  6. In the "good old days", many preamps or receivers came with a Rumble Filter, which is the HPF that T-bird is referencing. It can also be called a subsonic filter in some preamps.

    Even good, high-quality vinyl on a good turntable can experience these low-frequency problems. I'd recommend getting some sort of subsonic filter.
  7. Electricblue


    Feb 1, 2011
    Would a capacitor of a certain value in series with each side of the signal at line level do the trick? I wouldn't mind going home-made for a permanent solution, but if not I can probably tinker with the tracks in a DAW for now.

    Thanks for the help so far!
  8. Garyth

    Garyth Now What ..?

    Sep 9, 2013
    Punta Gorda Florida
  9. I just blew out a speaker on my stereo setup because of "rumble". I had removed an equalizer which had a subsonic filter. The subwoofer coupled into the turntable whenever I set the stylus on a disc (before rotation). It would clear up when the disc started moving. After a several times, one speaker had ripped the cone from it's rubber outer surround and farted out completely.

    The speaker that blew was not connected through the subwoofer, so it had the full range going to it. I finally added isolators to the subwoofer and the turntable to fix my problem.

    The subsonic filter is a better solution.