Crossover @ 120Hz: can 1 subwoofer produce high & low frequencies simultaneously?

Discussion in 'Archived Threads 2001-2004' started by Jeff Meininger, Aug 9, 2002.

  1. Jeff Meininger

    Jeff Meininger Second Unit

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    I have small mains. They have frequency response down to 80Hz, but the manual recommends setting the crossover at 100 Hz to 120 Hz. How, then, can one subwoofer driver (even a very high quality one) produce something like 35 Hz while it is also producing 120 Hz? How can it do this without distortion?

    A friend of mine whose advice I respect very highly says that my future upgrade budget would be better spent on TWO 10" subwoofers (pinnacle ac 100) than ONE DIY tempest 15" sonosub. I agree with him... it would allow one sub to be left and one sub to be right to limit "directional bass" effects above 80Hz (since my mains are so small). The 15" tempest probably doesn't perform well at the higher frequencies I'm looking to fill-in. But can a subwoofer be expected to produce clean, deep bass while also producing 110 Hz?
     
  2. Dustin B

    Dustin B Producer

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    How does a tweeter produce 3000hz and 18000hz at the same time?

    A 10" sub will not necessarily sound tighter, faster, cleaner or play to higher frequencies than a 15" sub. The overall frequency response has a lot to do with the driver (but there are other specs much more important than size in the frequency range you speak of), but the sound quality has just as much to do with the enclosure as the driver.

    From Adire's website Tempest specs:
    Distortion
     
  3. John Garcia

    John Garcia Executive Producer

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    My crossover is fixed at 100Hz, and I don't feel that the bass is directional at all. That's often cured with proper placement and calibration. I would bet the Tempest out performs the 2 10" subs.

    I'd recommend mains that go lower.
     
  4. Jeff Meininger

    Jeff Meininger Second Unit

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    It seems logical to me that a larger 15" driver would have a hard time moving fast enough to do the high frequencies well. Perhaps I just misunderstand the physics of this at a fundamental level?
     
  5. Dustin B

    Dustin B Producer

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    The cones are so rigid and light now, and the motors so powerful that cone size doesn't matter much anymore in the frequency range you are concerned about. That is until you start going past 18" drivers. Then you run into some rigidity problems.

    The enclosure will have significantly more to do with how the sub will sound in that frequency range than the cone size.
     
  6. Chris PC

    Chris PC Producer

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    You don't want your subwoofer reproducing higher frequencies because that makes the sound directional, meaning you can hear where the subwoofer is and thats distracting.

    Reproducing a 35 hz tone and a 120 hz tone isn't that difficult. Actually, that kind of reminds me of when I used to ponder how the heck a speaker or anything that is making sound for that matter, how could they be vibrating at more than frequency? I know this sounds silly, but it does make sense when you're a kid and just learning about it. I thought, how can a speaker move back and forth at say 80 hz while it is also moving back and forth at 500 hz? Luckily differenet wavelengths are different sizes. I just didn't realize as a kid that the speaker could be moving back and forth at 80 hz, while at the same time, it is moving back and forth at 500 hz, only the motion is smaller. Know what I mean? I wonder if that causes a dopler or group delay when a two way speakers mid-woofer is playing 50 hz bass tones and also voicing midrange of 2000 hz?

    Weird and off topic.

    Back to the topic at hand. Don't follow the instructions for using a 120 hz crossover. Use one closer to 100 hz.
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Think about the woofer moving slowly back and forth at 1 hz meanwhile vibrating rapidly. That's a 1hz test tone and say a 50hz tone at the same time.

    Complicate that a bit more and we have human vocals + cymbals + bass and drums with room echoes.
     
  8. Chris PC

    Chris PC Producer

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    Exactly. Its weird but it makes sense. Still though, if you think about a two way speaker woofer making a deep 40 hz tone and at the same time, it is also making a 2000 hz tone. Some of the 2000 hz tones would be higher and some would be lower as the speaker moves forwards and backwards. Weird.
     

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