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Thread: subwoofers and bass 101

  1. #1
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    Default subwoofers and bass 101

    Hello. I've got beginner's questions concerning subwoofers and bass in general. I have a NAD 370 amp and CBM 170s. I don't listen to music at high volume levels; e.g., my volume control knob never goes beyond the 9:00 position and mostly it's at around 8:00. I'm thinking about getting a subwoofer, but I'm wondering if they kick in at lower volumes, or do I have to turn up the juice to activate the subwoofer. If the latter is true, then maybe they're not for me.

    Also, if a speaker has a frequency range of 60hz-20khz, does this mean that tones of 40hz on a CD are absent during playback, or do you still hear something? A thank you ahead of time to anyone that may care to answer such elementary questions.

  2. #2
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    yeah you still hear the lower end of the bass, but the loudness decreases. so relative to everything else that can be happening at one time in music, the bass is a lot quieter. so when people say 'how low do they go' what they REALLY mean is 'what's the lowest they'll perform well at'. speaker manufacterers generally specify a hz range, +/- db. without that qualifier it's a useless measurement (you could say that the cbm170's do 20hz-20khz without specifying the db accuracy!)
    Last edited by bamputin; 02-05-2005 at 07:07 AM. Reason: spelhink

  3. #3
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    and to answer your question - yes if it's a good sub you will be able to tell the difference even at your 'quiet' listening preference.

  4. #4
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    Ditto what Bamputin said. Alot of subs have their own amplifier and internal crossover and most recievers have bass management and individual speaker level adjustments. You will be able to tune to your liking no matter what your amp/reciever's gain knob is set at.

    Randy

  5. #5
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    DB - one other thing - 'most' music doesn't have a lot of bass below 40 or 50 hz. If your setup is used for H/T as well as music listening, then I would definitely get a sub, but if it is strictly for music listening, and at a low volume at that - the price to performance of what you'll get may not be worth it. I would buy a sub that comes with a 15 or 30 day return policy no questions asked. This way you can judge for yourself if the expense is worth it or not.

  6. #6
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    Thanks to all for your replies. I'm impressed at how quickly I can get some help. Learned a few things this morning. I don't have an HT and not likely to in the near future, so I'll have to consider whether it is worth it to get a sub. I guess my thought was that I might be missing some low-end information in my music; I listen to a wide range of musci from classical to zeppelin, but not hip-hop or rap.
    Your responses did generate some other beginner's questions. What does it mean when a manufacturer states so and so +/- db following a Hz or frequency range? Is a lower number better? db is loudness right? Why is then that on some receivers, the louder you turn up the volume, the db numbers decrease on the digital display?
    Gotta run. I'll check in again later for your answers. Thanks again.

  7. #7
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    +/- dB means how far off a flat response a speaker or sub is over the given range of Hertz.

    For classical music stand up bass, the lower ranges of the piano and organ are likely missing. There is another thread here on the forum with links showing the range of some intruments. http://forum.ascendacoustics.com/showthread.php?t=700

    The other thing regarding bass and low volumes is the Fletcher-Munson curves. I may be over simplifying but bass isn't heard as well at lower volumes as higher volumes. That is why receivers used to have a loudness button to boost bass at low volumes.

    Last edited by Quinn; 02-05-2005 at 09:39 AM.

  8. #8
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    Quote Originally Posted by dodgerblue
    What does it mean when a manufacturer states so and so +/- db following a Hz or frequency range?
    You'll often see something like 35hz to 20 khz +/- 3dB's which means in the stated range, a certain frequency can be 3 dB's louder or 3 dB's lower than other frequencies at the same level. An increase of 3 dB's is about twice as loud as the rest, and a decrease of 3dB's is about the same ratio the other way. Usually how it works is the lower the frequency, the more it falls in the '-' category, and the higher the frequency, the more it falls in the '+' category. A speaker manufacturers quest is to maintain a flat line through a certain frequency range. Human hearing in general is only 20hz to 20 khz - so a 'perfect' speaker in terms of reproducing frequencies would be flat (+/- 0 db's) from 20hz to 20 khz. This is why Bamputin's comment of no +/- rating with a frequency range is spot on! If you look at David F's frequency charts on the 170's you'll see the peaks and valleys (and there are very few of those) in the stated range of the speaker.


    Quote Originally Posted by dodgerblue
    Is a lower number better? db is loudness right? Why is then that on some receivers, the louder you turn up the volume, the db numbers decrease on the digital display?
    dB's are rated lower to higher. Some receivers, like my H/K use ZERO decibels as a reference point (though not sure what the ref. level is). At ZERO it is far above listening level for me, so as I decrease the volume, I go to negative range. My H/K 520 does +8db's to -74 db's (or something like that). I usually listen between -30db's and -15 db's, depending on the source material (though I have had it up to -5 on older material not recorded very loud).

  9. #9
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    Okay. Some more good stuff to mull over! Thanks. Now it all makes sense when I read specs. I once saw a pretty small speaker claim to go 50-20kHz with no +/- dB spec and only a 4.5" woofer/mid; so, it probably did reproduce the range, but at levels far from flat, right?
    As, far as my earlier comment on how the numbers on some displays decrease to 0 as the volume increases, I think I missed the fact that the numbers were negative to start off, so actually they were increasing. Seems counter intuitive to use numbers in this way. Why don't they just start off with 0dB, which would be no decibels or no volume, and increase the values? Oh well.
    And going back to subs and low volume listening, turning up the gain on a sub would be like using a loudness button on a receiver, then? The frequency response then is skewed towards the low-end and is far from a flat repsonse, right? I think I get it. You guys have been very helpful. I'm sure I'll come up with more questions, as I read your replies. Good day!
    Oh, one other thing. How do you block off and select a quote to include in the reply?

  10. #10
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    The idea of 0 as reference is that you calibrated your system to 0 being reference level of 85dB or 75 dB whichever you subscribe to as being reference level.

    When I'm doing quotes like what you see I just add the mark ups [qoute] and [/qoute] and deleted the rest or if you scroll down when you're posting. The thread is below and I just copy and paste it and put in the quote mark ups. I intentionally misspelled quote in the mark ups so you could see the mark ups.
    Last edited by Quinn; 02-05-2005 at 03:18 PM.

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