Speaker Frequency

Discussion in 'The Projects Forum' started by ParadiseMusic, Nov 25, 2009.

  1. ParadiseMusic

    Thread Starter New Member

    Nov 25, 2009
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    I'm working on an amplifier project for my electronics class and im trying to find what the best frequency for certain speakers is? I've been experimenting with an equalizer and the sub for the project and i think the crossover circuit should cut off frequency at the sub around 250hz? is this right?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    Well, it really depends on the individual speaker.

    Did you check the manufacturer's specifications for the speaker?

    Seems to me a sub-woofer would be for just very low frequencies; you'd use a normal woofer for say, 100Hz-800Hz or so.

    But check out this Wikipedia entry:
    http://en.wikipedia.org/wiki/Subwoofer

    [eta]
    Usually, speaker crossover networks use LC filters. The inductors can be pretty large (they look like transformers); so can the capacitors. Butterworth filters are usually preferred for audio, as they have a very flat passband, and taper off gracefully.

    However, with a subwoofer, you might opt for a more steep cutoff frequency that could be provided with a Chebyshev filter.
     
    Last edited: Nov 25, 2009
  3. ParadiseMusic

    Thread Starter New Member

    Nov 25, 2009
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    ill look into that but these speakers were using seem to not have model numbers on them so i have no idea what they are rated for frequency wise. they do have the rms wattage rating on them though. if i applied the max rms wattage to them and started at 20khz and made my way down until the speaker stop distorting wouldn't i find it?
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    No, don't do that!

    I would start at around 120-150Hz, and slowly go up in frequency until it began distorting.
    Then go back down in frequency until it started distorting again.
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    It probably depends more on the cabinet than on the speaker driver. The cabinet will form a resonant and/or damped system and the speaker itself is just a small part of that system. Good speaker cabinet and crossover design is very difficult, even an expert can still get it wrong, after doing the calcs and running the software it can be common to still build the thing a couple times over to get the speaker cabinet dimensions JUST right.

    Good crossover design (or speaker design) is a real art.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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    The speaker itself is very significant. A 2" speaker with a 1 oz voice coil assembly will not reproduce bass, at least in comparison with a 12" speaker having a 4" 8 lb voice coil.
     
  7. ParadiseMusic

    Thread Starter New Member

    Nov 25, 2009
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    yes i see how that would be much safer. In my class we have a lot of donated broken equipment and the speaker were using for the sub woofer is 12" with the voice coil being 8". the whole speaker weighs probably 8-10lb's. It was pulled from a bass guitar amplifier.

    One of the big problems of doing the frequency check is that the speaker is rated for 250w rms and is going to be loud doing this so i may have to find another way.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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  9. Audioguru

    New Member

    Dec 20, 2007
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    A speaker for a bass guitar makes a lousy sub-woofer. It is made for high efficiency at 100Hz to 150Hz which are far higher frequencies than a sub-woofer produces.

    The enclosure for a raw speaker must have a design for the spec's of the raw speaker that is used. The spec's are the volume, the damping material and whether the enclosure is ported.
     
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