Sub Amp problems

Discussion in 'Home Theater Projects' started by DaveWo, Sep 8, 2006.

  1. DaveWo

    DaveWo Auditioning

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    Hello,

    A few years ago I purchased a subwoofer from accousticvisions and an amp from parts express. I believe the sub was called a DPL12? And the amp is the 250 watt parts express amp. So far I have been very pleased with the performance of this combination.

    However, recently, my sub does not seem to be working correctly. In order to get any sound at all to go through it I have to crank the crossover almost all the way to 160hz. Once I crank that over I have to really turn up the volume to get anything at all. It did not used to be like this.

    I have tried switching the cable connecting the setup to my sony receiver, but have not had any luck with different cables. I am wondering if there is something else I can do to troubleshoot this, or if maybe my amp has just gone bad? Any help would be appreciated. Not sure if i provided enough information, so just ask if you need more. Thanks!!!
     
  2. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Please give us a little more detail:
    What have you changed since it was last working properly?

    When you say you have to crank "the volume", do you mean the volume of the receiver or the level control (gain) on the sub amp?

    As you crank "the volume" way up, does the volume increase in a linear fashion or does it go from nothing to really loud all of a sudden? The latter may indicate that the amp may not be reliably switching to active mode. Sometimes this can be addressed by changing the subwoofer calibration level in your receiver to get more signal to the amp.

    This amp has a 3-way power switch: off, auto, on. Also, the LED light will glow red when the amp is inactive (asleep) and green when it is active. You're probably running the amp in "auto" mode so that it can decide when to switch on and off. Play some music at a very low volume level and slowly increase the receiver's volume until you see the LED change to green. That'll tell you when the amp is turning on. Also you can try just switching it to "On" to force it on and see if that fixes the problem.

    If none of this helps, you could try using some other amplifier to power the woofer. That might tell you whether the problem is in the sub amp or in some other part of the chain.
     
  3. DaveWo

    DaveWo Auditioning

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    I haven't changed anything since it worked properly. I think it was working just fine at my old apartment, then I moved it home for the summer, got there and it didn't work so well. Then I moved it into school a week or two ago and it still isn't working correctly.

    What I meant by "volume" was the level (gain) on the amp.

    The volume increases linearly.

    I do run the amp in auto mode. THe light turns green pretty quickly, with a low volume level from the receiver. So it is receiving a signal.

    What would be the proper crossover setting for this type of sub/amp combination? It seems like I shoudln't have to turn it all the way to 160hz to get anything coming through.

    Also, when I do turn the crossover to 160hz and turn the volume way up, it doesn't seem to have the greatest sound quality, and is almost poppy at times.

    Sorry if this is all too vague, I'm not really sure how else to describe it, I just know that it doesn't seem to be working like it used to.

    I'm not sure where I can get my hands on something else to power the woofer. Well, I'll keep experimenting, let me know if you have any more ideas.
     
  4. DaveWo

    DaveWo Auditioning

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    Ok, so, I just went and fiddled with it some more, and suddenly it works fine now. I don't know what the deal was. It did this to me when I first built the thing too, and then suddenly worked fine. I didn't even change anything. But now it is super loud and clean, with the gain set at about 25%. Crossover is still set near 160, but it sounds fine, not too many highs or anything. Thanks for the help. This thing frustrates me sometimes.
     
  5. Brent_S

    Brent_S Second Unit

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    Exploring one of Ryan's thoughts further. I'd say you've changed everything twice since it last worked correctly by virtue of disassebling and reassembling the system each time.

    Did you recalibrate after moving? Assuming this is a surround sound receiver, you level settings could have returned to their defaults while the system was unplugged. Likewise, the bass management settings could have also reset to default.

    If you're using the crossover in you receiver, you'll want to set the sub amp's xover to it's highest setting to get it "out of the way".

    It could simply be moving damage to either your receiver or sub amp.

    -Brent
     
  6. DaveWo

    DaveWo Auditioning

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    Ryan,

    Yes, you are correct, in a sense I have changed the system twice, by moving it.

    After moving both times, I did readjust bass, treble, and subwoofer levels on my receiver.

    I hook the sub up to a "sub out" jack on the back of the receiver, is that what you meant by using the receiver's crossover? I didn't realize that would mean I shoudl set the amp's crossover all the way up, but that makes sense now that I think about it.

    Either way, things are better now so I am happy. And hopefully I won't have to deal with it all again any time soon. It's not much fun having your roommates get all excited about this "big" subwoofer that you brought to the apartment, only to plug it in and barely be able to hear it. Oh well, after today they've gotten plenty of "foot massages" from the floor shaking [​IMG] Thanks again guys!
     
  7. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Brent, you nailed it. Everything changed.

    Could be a flaky connection somewhere. I get this occasionally with my CD player. Sometimes after reworking the wires I don't get any sound out of the left speaker when playing the CD player. I fiddle with the RCA connection and poof - it works ... at least until the next time I start changing things.
     

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