Tweaking your cross-over?

Discussion in 'Archived Threads 2001-2004' started by Steve Stogel, Jan 14, 2002.

  1. Steve Stogel

    Steve Stogel Supporting Actor

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    I assume this is the right area for this question. I've got a dbx subwoofer amp that I plan to push a 25-31CS SVS with. Problem is it only has speaker level inputs/outputs and the cross-over is set at 200Hz. I'd love to have something that converts line level to speaker level (which would go into the sub amp), but that's more commonly known as an amp. I can't use the subwoofer out on my receiver because the amp doesn't have a line level input. So are there any ways to get that cross-over down to 80Hz?
    What can I do short of running right out and buying another amp? Someone else told me that making the SVS go all the way up to 200Hz is not a good idea. It's going to be in a corner in front of the TV and front speaks, so localization isn't really an issue, but I don't want the SVS to be hindered in any way.
    Any opinions or help would be appreciated. [​IMG]
    Steve
     
  2. Mike_A

    Mike_A Stunt Coordinator

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    can you cross it over in your receiver?

    you'll get bass below the receivers crossover (probably 80hz) and the LFE channel (up to 120hz, but usually not that high) out of the sub out. you can even disable the crossover on the amp (ideally you would actually).
     
  3. Steve Stogel

    Steve Stogel Supporting Actor

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    That's the problem. Since the sub amp doesn't have line level, I can't use the sub out. My receiver has A/B outputs, so I've been sending A to the fronts and B to the sub amp (in speaker level). It's the sub amp whose crossover is set at 200Hz, but since I can't use the sub out, I've just got to send the B output (20-20K bandwidth) to the sub amp. The sub amp has outputs for the sub (speaker level) and the fronts (speaker level). I don't use the output to the fronts. I use the A output on the receiver to go to the fronts (also full bandwidth). So my sub gets 20-200Hz and my fronts get 20-20K. Ideally I'd like to just give the fronts 80 and above, but I can't figure out a way. I think Paradigm has a seperate crossover unit, but I'm not even sure that that one would work since it would still need to have speaker level out. This speaker level thing is going to drive me nuts.
    Nobody happens to have a dbx XB150 sub amp that they've modified the crossover, huh? Didn't think so [​IMG]. Anywho, am I understanding what you're getting at, Mike? I think I know what you're saying, but as I said, the sub out is pretty much out of play, and I think my options are either limited or nonexistent. Thanks for the input, Mike.
    Steve
     
  4. Mike_A

    Mike_A Stunt Coordinator

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    ok i see what you're saying. well, sounds to me like the easiest thing may be to try to add a line level input. if you can trace the signal to where the speaker level inputs have been coverted to line level (and they should be before going to the amp). that may be easier than modding the crossover. just a thought, otherwise i'm out of ideas...
    actually, i do have one more idea - i'll take that SVS off your hands and then no more problem [​IMG]
     
  5. Steve Stogel

    Steve Stogel Supporting Actor

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    Is it possible to convert from line to speaker level or vice versa? I was under the impression that it was not possible. I thought perhaps I could convert the line level sub out to speaker level to feed into the sub amp (hence having an 80Hz crossover), but it seems that the only thing that converts line level to speaker level is, unfortunately, and amplifier. Well, mine doesn't. Is there anything else out there that can convert line level to speaker level (say a very inexpensive attenuator or something)?
    Steve
    P.S. As far as giving it away, I may have to wait and see how it works out first [​IMG].
     
  6. Ron Shaw

    Ron Shaw Stunt Coordinator

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    Its going to take an amplifier. The crossover in the sub is a high level passive crossover. It takes current to drive a loudspeaker, so no way of voltage step up from line to speaker level is going to work. It would be best to crossover at the desired frequency electronically, and bypass the passive crossover in the sub. Passive crossovers, (at very low frequencies) arent ideal for the job, as it takes large electrolytic caps and large inductors, both which affect sound quality and damping factor.
     
  7. Mike_A

    Mike_A Stunt Coordinator

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    well what i meant was that your sub amp is converting it to line level at some point most likely. if you could find what point that is and bypass the conversion from speaker to line level, you might be able to create your own line level input.
    did that make any sense?
    and if you give up on the SVS, definitely get in touch with me [​IMG]
     

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