Sub EQ Results .... Comments? Suggestions?

Discussion in 'Archived Threads 2001-2004' started by Gary Thomas, Dec 11, 2001.

  1. Gary Thomas

    Gary Thomas Second Unit

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    Hi. I'm using an ART 351 1/3 EQ set at a 12db range with a HSU VTF 2 subwoofer crossed over from a Denon 3802 at 80hz measured at about 6 feet. I've calculated the Radio Shack sound meter adjustments. Here's the 1/6 octive results...

    25hz - 70

    28hz - 70.5

    32hz - 73.5

    36hz - 73.5

    40hz - 71.5

    45hz - 72

    50hz - 70.5

    56hz - 61.5

    63hz - 70.5

    72hz - 72

    80hz - 70.5

    89hz - 73.5

    100hz - 70.5

    They seem to look good at the 1/3 octives...25, 32, 40, 50, 63, 80.

    There is a huge dip at 56hz that I'm not sure if I can get to w/o a parametric eq.
     
  2. ling_w

    ling_w Second Unit

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    If your pre/proc/receiver allows:

    You could select the crossover freq on the it to be 50hz

    Select crossover freq on the Hsu sub to be arouund 60-65hz

    Disable low pass xo on the pre/pro/receiver.

    Fine tune the Hsu sub xo until you get the smallest dip/hump in that region.
     
  3. David Judah

    David Judah Screenwriter

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    Are you measuring from your listening position?

    You could reposition the sub, but of course you would have to remeasure and re-EQ. Even with a parametric EQ there is no sense in trying to boost a room induced null.

    DJ
     
  4. Gary Thomas

    Gary Thomas Second Unit

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    Thanks for the replies.

    The Denon can only be crossed over at 80 & 100. My mains are rated down to 50, so I picked the 80.

    I measured from the center of the room. My main listening position is about 5 feet further back. I'll remeasure from there...but does this make a huge difference? How would I handle a situation with different measurements from the 6 seats in the room?
     
  5. ling_w

    ling_w Second Unit

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    Measuring from center would certainly produce a null on every odd modes. So please measure again at your listening position.

    BTW, where is you sub placed, and what is your room dimension & your listening position?
     
  6. Wayne A. Pflughaupt

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    Gary,

    Your readings look pretty good. However, I notice response is essentially flat from 100 to 25Hz. You will probably find that things sound better if you EQ in a “house curve,” or gradual rise in response. This should sound more natural than flat response. The amount of rise needed is room dependent; smaller rooms need more than larger rooms. As a “starting point” to get you going, my system has a gradual 8dB rise below 125Hz; my total listening area encompasses 6200 cubic ft. You should include all areas open to the HT room – hallways, dining room, game room, etc. – when determining your total listening area.

    It will probably be best to level off the rise somewhere between 30-40Hz. I found if response kept rising below that point, what I got a lot of annoying, extraneous super-low freq energy that was distracting and unnatural-sounding. Experiment to find the appropriate curve and leveling-off point for you room.

    The ultimate goal, of course, is smooth response. The best way to test your EQ and house curve is with music. Use a few CD tracks that have bass lines that run from high notes to low notes. The bass should sound smooth and even from note to note. If the highest notes sound week and the lowest notes sound “bloated” or severe, then reduce the amount of house curve. As an example, if you listen to said CD tracks with your current EQ settings, I’ll bet you will find the lowest notes are weak.

    I also found that a separate bass level is needed for movies and music. Usually what sounds good in movies is “too much of a good thing” for music.

    It is not necessary to move the sub around the room looking for that “magic spot.” That is for people who don’t have a dedicated sub EQ. What they end up with is response characteristics they can live with at the expense of extension and output. Not to mention, often the “response they can live with” is so ragged that even equalization cannot correct it. Since you have an EQ, the best place to put your sub is in a corner, the one with the longest uninterrupted wall length in both directions. This will result in the best unequalized response characteristics and minimize the effects of room nulls. Of course, there will be a few response peaks, as you already know. After EQing them out you will have the test of everything: the smoothest response, the lowest extension, and the highest output.

    As far as where to take readings, take them from the primary listening position, as David noted. Of course, things will read much different if the primary position is against the wall vs. away from the wall. You will probably get better results if the seat is at least 6-10ft. out from the back wall. If you take your readings from at a central seating position away from the back wall, I have found that this will result in acceptable response at all seating positions in the room except those against a wall.

    Hope this helps.

    Happy Holidays,

    Wayne A. Pflughaupt
     
  7. Gary Thomas

    Gary Thomas Second Unit

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    Thanks Wayne. I appreciate your detailed response. I had heard of a "house curve", but had not seen the amount of increase as the frequency gets lower. Your 8db example gives me a great starting point.

    Ling: my sub is corner loaded in the right front corner of my room. The main room is approximately 2600 cf. The adjacent kitchen is 1800 cf. There is also a hallway / foyer that is about 1000 cf for a grand total of 5400 cf. The primary sitting area is 12 feet from the tv & 14 feet from the front wall.
     
  8. Kevin C Brown

    Kevin C Brown Producer

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    Wayne- 2 comments:
    1) I would presume that to somewhat mimic the "house curve" that you mention, then you could simply *not* apply the correction numbers to the Radio Shack SPL meter. Just use it as is with a test disc. (In other words, set up your system so that it mimics the C weighting response in the RS meter, which actually is based on how people perceive sound at different freqs.)
    2) But for me, myself, and I, *flat* frequency response is the holy grail, and actually what I'm used to. If I tried to do a "house curve" in my system, to me, it would sound as if there's too much bass.
    And that would also apply to music vs movies. Maybe because I have listened to both with "flat" freq response for so long, to me, that sounds the best. (For example, I remember one person saying that Star Wars Episode 1 had too much bass in his system, and that he had to turn it down. I thought that was odd, because it sounded fine in mine.)
    But as you allude to, everyone has to judge for themselves what they think sounds best in their own systems and environments... [​IMG]
     
  9. Brian L

    Brian L Cinematographer

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    I'm with Wayne on the house curve.

    In fact, with everything set for flat response in my room (as flat as my Bijou and SpectraPlus can get it), the bass on most material sounds a bit anemic (I run a HSU 1225 and a pair of B&W 604's, crossed over at 80Hz). I actually have about a 10 dB rise from 80 Hz down to 25Hz (the practical limit of the sub).

    I am one of those folks that find the SWTPM had a bit too much bass for my liking (given the set-up described above). I tend to drop the sub level about 3 dB for that title. I would concede that it may sound resonable on a truly flat system, but it and perhaps U571 are the only two titles were I do feel the need to drop the level a tad.

    There is a huge variance in bass quantity and quality from title to title, but I find that most material does indeed sound better to my ears with a house curve. You will have to be the judge of that on your own system, though.

    All that said, what you like or dislike about bass is purely a matter of taste. There is no right or wrong. If it sounds good to you, it is good.

    Enjoy!

    Brian Leduc
     
  10. Wayne A. Pflughaupt

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    Actually Kevin, I’m willing to bet you do have a house curve. If you have an RTA, a spectrum analysis program or a test disc with filtered 1/3 octave pink noise test tones, you will probably find that measured response is at least several dB lower at 16kHz than it is at 40Hz. [​IMG]
    If you didn’t like a house curve applied to your sub, perhaps you never “got it right?” It can be tricky and time consuming. It took me something like 10 hours of tweaking and listening before I was satisfied. If you applied too steep a curve, or extended it all the way down to 20Hz, I can understand why you weren’t pleased with the results.
    If you have some music like I mentioned, with bass notes running from high to low, and have uniform extension down to the lowest notes, then of course you have achieved the “Holy Grail.” The lowest notes should be felt as well as heard. (If you need, I can recommend some good CDs for this purpose.)
    If not, I suggest trying to set the sub’s curve via the directions in my previous post. Especially critical, I feel, is the point where the curve levels off. Try 2-3 different frequencies between 30 and 40Hz. I think this more than anything else makes the difference between a good curve and a boomy one.
    Start with a minimum boost, say only 3-4dB. If the lowest notes are still not “up to snuff,” try a couple more dB of boost. Maybe in your situation the curve doesn’t work spread from 100 to 30Hz. Maybe it should be spread from 125Hz down, or perhaps not start until 80Hz. The thing to do is experiment and listen, and as you said, judge for yourself what sounds right. [​IMG]
    Happy Holidays,
    Wayne A. Pflughaupt
     
  11. BruceD

    BruceD Screenwriter

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    Wayne,

    Go ahead and recommend those CDs here now, enquiring minds want to know.

    Thanks for all your contributions, they certainly helped me in my quest for that satisfying foundation to my music.

    BruceD
     
  12. Kevin C Brown

    Kevin C Brown Producer

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    Wayne- I just use the following calibration numbers to adjust the readings I get from the Radio Shack meter.
    http://www.hometheaterforum.com/uub/...17-000048.html
    So far, I have been using the Autosounds 2000 CD, 10 - 98 Hz by 1 Hz increments. I just got the Stryke disc, that has from 20 Hz to 20 kHz by 1/6 octave increments.
    My biggest problem, is a very deep dip around 48 Hz. Getting the phase between my sub and mains correct helped, but it may just be an interaction between the mains and the floor that can't be easily corrected.
    (Although the next easy thing I can think of, is to try and change the crossover for the mains from 80 to 60 Hz. I don't want to go any lower than that, due to how low I think my mains go.)
     
  13. Wayne A. Pflughaupt

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    Bruce,
    Well, these aren't any of those "Bass Extravaganza" CDs, but each of these will tell you something about your sub, how well it's EQ'd, and how well in blends with your mains.
    The CDs I use are:
    • Basia London Warsaw New York. As with all Basia’s releases, the bass is superbly recorded. Track 1, “Cruising for Bruising,” has a lot of action on the low B-string of a 5-string bass. However, even though the notes are low the fundamentals aren’t there; my RTA shows response rolls off at 63Hz. But in any event, the bass is well-recorded and each note should be clear and distinct.
      Track 5, “Ordinary People,” is the one I use for octave-to-octave linearity. The bass line runs up and down almost two full octaves. The lowest “D” note at the 2:53 mark registers a solid 40Hz on my RTA, meaning the fundamental is present. The upper notes should be distinct and clear, and as the bass line descends you can begin to “feel” as well as hear the notes, and the “feel” intensifies the lower the notes go.
      Of course, the bass guitar easily goes an octave or more higher than what’s on this track, but this one transverses the range well above and below the crossover point, which will show you how good your sub and mains blend.
      Incidentally, the opening song “Drunk on Love” of another Basia CD, The Sweetest Illusion, is a great track to test bass detail. The bass has a “texture” or “growl” that should be readily apparent. A boomy, ill-defined sub will obscure the “texture.”
    • Ramsey Lewis Ivory Pyramid is the CD I use for extension. Be warned, this CD has the bass recorded very hot. I have to turn the sub way down to get a proper blend with the mains. Track 2, “People Make the World Go ’Round,” has several sequential descending notes on the B-string of a 5-string bass that get down to bottom of the neck. This phrase repeats two or three times, the first time at about the 1:00 mark. Once again, the lower the notes go the more you should feel them. The lowest sustained note hits a solid 31.5Hz on my RTA, indicating the fundamental is there in spades, as it were. There is also significant energy at 25hz in this note as well.
      An example of what to expect if you sub doesn’t get down there all the way: I played this track in my son’s car with a pair of medium-quality 15” subs in an undersized box. It did pretty good as the notes descended, except for the bottom two. On the way down you could “feel” the notes as well as hear them, but with the last two notes the “feel” wasn’t there. This sub probably bottomed out at about 50Hz with response falling like a brick below that point.
    I don’t know if you can find the Basia and Ramsey Louis albums new any more, but you can get them on e-bay.
    Kevin,
    This 46Hz problem might be boundary-induced. If you have the sub about 7-7½ ft. from a wall, that would account for it. Since you have an equalizer, the sub should be in a corner, as I mentioned above. In addition to the benefits I already mentioned, corner placement minimizes (but not entirely eliminates) the effects of a room-induced null.
    If it is already in a corner, try a different one, if possible.
    Happy Holidays,
    Wayne A. Pflughaupt
     
  14. BruceD

    BruceD Screenwriter

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    Wayne,

    Thanks for the info on the music CDs, I'll take a look at my favorite used stores and see what pops up.

    Have you listened to any of the bass (guitar, stand-up, and cello) on Sara McLahlan's albums?

    Happy Holidays

    Bruce
     

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