Where did my lows go?

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  • 02-26-2009, 06:19 PM
    audio amateur
    Come here and you'll believe it.
    Quote:

    Originally Posted by Feanor
    You may feed your system 40 Hz and you might get -3 dB. But here's the catch: you might not be hearing a pure 40 Hz sound. Instead you are getting distortion.

    In a rooms too small to reproduce a certain frequency, all that power you're feeding has to go somewhere. It creates distorted sound at a higher frequency than the input signal.

    I think it's safe to say I can hear the difference between a disorted 40Hz sound and one that is not. A 40Hz sine wave doesn't sound anymore distorted than one of 80Hz, at a reference amplitude. The cone's excursion is well within its limits when I do this. My room seems to produce a peak between approx. 40 and 45Hz which helps to extend the 686's bass. I was quite dumbfounded at first with their bass extention.

    'YMMV', as they say around here. But I don't think you're in a position to argue :frown2:
    or perhaps I'm utterly wrong and i've forgotten something in the equation..
  • 02-26-2009, 06:58 PM
    atomicAdam
    Quote:

    Originally Posted by audio amateur
    I think it's safe to say I can hear the difference between a disorted 40Hz sound and one that is not. A 40Hz sine wave doesn't sound anymore distorted than one of 80Hz, at a reference amplitude. The cone's excursion is well within its limits when I do this. My room seems to produce a peak between approx. 40 and 45Hz which helps to extend the 686's bass. I was quite dumbfounded at first with their bass extention.

    'YMMV', as they say around here. But I don't think you're in a position to argue :frown2:
    or perhaps I'm utterly wrong and i've forgotten something in the equation..

    what about diagonal distance? from the bottom left corner to upper right corner.

    maybe there is enough distance there to let the wave travel. rooms arent 2D
  • 02-28-2009, 01:21 PM
    JoeE SP9
    I did a quick calculation using the longest diagonal in the room the Fq that resulted was 75Hz. This is using 8Ft. as the ceiling height.
  • 03-03-2009, 05:32 PM
    Doc Sage
    To take this one step further...

    Does this explain why, when you hear loud music coming from a car, the bass thump always seems to be at the same frequency?

    Doc Sage
  • 03-03-2009, 05:44 PM
    02audionoob
    Quote:

    Originally Posted by atomicAdam
    what about diagonal distance? from the bottom left corner to upper right corner.

    maybe there is enough distance there to let the wave travel. rooms arent 2D

    And in one more direction...what about the diagonal from front bottom left to rear top right?
  • 03-04-2009, 05:48 PM
    JoeE SP9
    Quote:

    Originally Posted by 02audionoob
    And in one more direction...what about the diagonal from front bottom left to rear top right?

    See my post No. 28 in this thread.
  • 03-05-2009, 09:32 AM
    E-Stat
    Quote:

    Originally Posted by audio amateur
    I think it's safe to say I can hear the difference between a disorted 40Hz sound and one that is not. A 40Hz sine wave doesn't sound anymore distorted than one of 80Hz, at a reference amplitude. The cone's excursion is well within its limits when I do this. My room seems to produce a peak between approx. 40 and 45Hz which helps to extend the 686's bass. I was quite dumbfounded at first with their bass extention.

    I'm largely agreeing with your assessment, but do have a couple of caveats based upon Feanor's comments:

    1. As you indicated, the primary frequency of your room is around 45hz so you are getting some room gain. If the other walls are even multiples, this factor will be enhanced. My room back in Atlanta was 30x15x7.5. The fundamental frequency was just below 20 hz, reinforced by the room multiples and created a most entertaining bass effect near the back wall. The bass drum on Dead Can Dance's "Yulunga" cut shook the room. Not real, but fun! My current room is more neutral and lacks that euphonic reinforcement.

    2. The primary distortion component of dynamic woofers is doubling. Which as the name suggests is second order harmonic distortion delivered at relatively high levels for small drivers at the bottom octave (up to10% or so) as compared with amplifiers. Aside: Feanor often opines that tube fanciers favor them because of this same factor. First of all, the magnitude of distortion with phono/line stages remains in the fractional percent category. Even my '81 ARC SP-6 had only 0.01%. With tube amps, not only is the peak result much lower (3%), the figure remains below 1% up to -3db output for modern pentode designs. So, back to speakers - what does that mean? Woofer distortion sounds good. Some may say better. It is consonant to the fundamental and adds "richness". Some of what you are hearing could be doubling even when the driver is within its excursion limits.

    rw
  • 03-05-2009, 09:55 AM
    GMichael
    I seem to get very good bass from my car system. Sounds great. Very low. Very little distortion.
  • 03-21-2009, 05:07 PM
    yogo
    Quote:

    Originally Posted by atomicAdam

    The speakers are pointed length wise

    I've read somewhere on this site that in a long room you should not run your speakers lengthwise. More like this:

    xxxxxxxxxxxxxxxxxxxxx
    x---------O----------O----------x
    x----------------------------------x
    x----------------------------------x
    x----------------------------------x
    xxxxxxxxxxxxxxxxxxxxx

    than this:

    xxxxxxxxxxxxxxxxxxxxx
    x---------------------------------x
    x O------------------------------x
    x--------------------------------- x
    x O-------------------------------x
    x----------------------------------x
    xxxxxxxxxxxxxxxxxxxxx

    Worth a shot if nothing else works. That might tame any undesirable effects between your speakers and sub. Luck...
  • 03-21-2009, 05:22 PM
    Auricauricle
    So it sounds like, unless you have accomodations of space to support frequencies produced by the subwoofer, your screwed!

    Boy, I can imagine quite a few thousand audiophiles are getting pretty hoppy, now!
  • 03-21-2009, 06:09 PM
    atomicAdam
    Quote:

    Originally Posted by Auricauricle
    So it sounds like, unless you have accomodations of space to support frequencies produced by the subwoofer, your screwed!

    Boy, I can imagine quite a few thousand
    audiophiles are getting pretty hoppy, now!

    Hoppy? Sure does make you wonder.

    Well, at least for me it should only be a month or two more in the small room. If Bush did anything I could thank him for the economy and housing prices are so screwed up I can affors a house.
  • 03-22-2009, 11:04 AM
    Auricauricle
    Yeah, "hoppy". As in quite upset, miffed, po'd, peeved, irked, irritated, annoyed, riled, fed-up, ruffled...

    ;)
  • 03-22-2009, 11:18 AM
    atomicAdam
    Quote:

    Originally Posted by Auricauricle
    Yeah, "hoppy". As in quite upset, miffed, po'd, peeved, irked, irritated, annoyed, riled, fed-up, ruffled...

    ;)

    IC - that is what I thought.

    For me Hoppy = <img src="http://www.stonebrew.com/tasting/ruination/design/pfront.gif">