Help with crossovers.

Discussion in 'Speakers' started by Jesse Sharrow, Dec 13, 2003.

  1. Jesse Sharrow

    Jesse Sharrow Supporting Actor

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    I have some boston VR-950 towers. They are a dual 5 1/4's. They play pretty low, there response is 46Hz-20kHz. What do you think I should cross my sub over at? Can I do it as low as 60hz? I know I shouldnt do it right at 46 but is 60 enough leeway?
     
  2. Phil A

    Phil A Producer

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    Bass frequencies sum. You should do some type of measurement in your room, if not with an RTA, then with a SPL meter and a test disc with tones (or download them from a place like - http://mdf1.tripod.com/test-tones.html). So that if your speakers are truly roling off around 46HZ in your room you would want the crossover (for music not ".1") likely somewhere around 40HZ give or take a drop either way (measurement would be best). If you speakers truly roll-off at 46HZ setting the crossover at above that point, depending on the room response curve of your speakers, is likely to produce a bass bump which may sound boomy. If you like stuff that way based on what you listen to that is OK.
     
  3. DaveDickey

    DaveDickey Stunt Coordinator

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    Phil,

    I'm pretty new to HT and I'm a little confused by your previous post. This is not intended as a "flame" or anything. I'm just trying to learn.

    If Jesse's speakers cut out at 46HZ, shouldn't he set his crossover above that point? Say at 50 or so? If his speakers stop producing sound at 46 and his sub does not kick in until 40, isn't there a "dead zone" there between 46 and 40?

    My main speakers go to 35Hz and the factory recommends a subwoofer setting of 40Hz.

    Thanks, Dave
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    Crossovers are not brick walls. They have a very significant slope to them. So by setting the sub crossover below the crossover point at the speakers, the speakers are still producing significant quantities of bass, as is the sub. This depends on how the speakers roll off at the low end, how the sub crossover works, and whether there is receiver crossover going on. Using an SPL meter is the best way to do this, to get flat response.

    It's also very difficult to rely on ratings, as a lot of companies will exaggerate the bass extension of speakers.

    Second, if you are setting your speakers as small, and letting the receiver to the bass management, then the crossover point of the receiver is around where you need to set the sub's crossover to eliminate a bloom in bass where the speakers and sub overlap, or just set the crossover all the way up and not worry about it (only for HT with speakers set small).
     
  5. Lew Crippen

    Lew Crippen Executive Producer

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    I’d start at 80 Hz or 90 Hz. This crossover point will still require your main speakers to reproduce sounds down to 40 Hz or 45 Hz or so. I am not sure of the specifications of those particular Boston speakers, but there are very few speakers that provide flat output down to 20 Hz.

    It will depend on exact type of crossover in your receiver, but in general you can expect that your main speakers will still be reproducing sounds at half the crossover point.
     
  6. Phil A

    Phil A Producer

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    Dave - I think the response by Chris covered the topic pretty well. It is a function of the speakers, the room, the volume control of the sub, etc. Really too hard to predict for every situaion. That is why an RTA or a test disc with tones (e.g. http://www.delosmus.com/cgi/cart/ite...60091071438005) and an SPL meter to do the right thing for your situation.
     

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