I'm trying to understand subwoofer crossover

Discussion in 'Beginners, General Questions' started by Donald_S, Nov 18, 2003.

  1. Donald_S

    Donald_S Stunt Coordinator

    Joined:
    Oct 19, 2003
    Messages:
    103
    Likes Received:
    0
    I've bought a Daytona 100 watt sub and Panasonic D912k receiver that I guess is around 80 watts a side. My front speakers go down to 50hz with a sensitivity of 89db (Fluance if it matters). The lowest crossover setting for the receiver is 100hz.

    Here is what I don't understand. If I set the receiver for the lowest crossover I can have the sub drive everything below 100hz. Or I can set the receiver for large speakers with no crossover. Would I then set the sub to crossover at 50hz? And which of these makes more sense? Should I make the fronts or the sub work harder?

    Thanks bunches guys.

    Donald
     
  2. Lee Carbray

    Lee Carbray Second Unit

    Joined:
    Oct 23, 2002
    Messages:
    308
    Likes Received:
    0
    100Hz is a pretty high crosover but I would still suggest uning that and setting the mains to small. The reason being is that I bet your sub goes a lot lower then 50Hz.
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0


    Keep in mind if you go with LARGE setting, the only thing sent to the sub is dedicated LFE, regardless of the x-over setting on the sub.

    The large setting means all full range main signal will go to the appropriate full range main speaker... unless you have your sub wired in line with your mains, the only way you're going to get bass (beyond the dedicated LFE stuff) to the sub is by setting speakers to small.

    100hz is not an ideal crossover point- but I think it's better than the alternative.

    -Vince
     
  4. John Garcia

    John Garcia Executive Producer

    Joined:
    Jun 24, 1999
    Messages:
    11,571
    Likes Received:
    24
    Location:
    NorCal
    Real Name:
    John
    100Hz is OK depending on the main speakers, and since yours are rated to 50Hz, it is practically ideal. Your mains will receive frequencies down to 50Hz, possibly lower depending on x-over slope. I would not recommend setting these speakers to large for the reasons Vince mentioned. If your speakers cannot handle lower bass (30-40Hz) on their own, they are better off set to small. You want the sub to work harder, as that is what it is for.

    As for the sub, when you are using the receiver's x-over, you should set the sub's internal x-over as high as it will go to avoid cascading them together.
     
  5. Jack Shappa

    Jack Shappa Second Unit

    Joined:
    Jan 24, 2003
    Messages:
    411
    Likes Received:
    0
     
  6. Lew Crippen

    Lew Crippen Executive Producer

    Joined:
    May 19, 2002
    Messages:
    12,060
    Likes Received:
    0
     
  7. John Garcia

    John Garcia Executive Producer

    Joined:
    Jun 24, 1999
    Messages:
    11,571
    Likes Received:
    24
    Location:
    NorCal
    Real Name:
    John
     
  8. Donald_S

    Donald_S Stunt Coordinator

    Joined:
    Oct 19, 2003
    Messages:
    103
    Likes Received:
    0
    Man I'm glad I asked. Not anywhere as simple as I thought, but logical if you think about it. I could set the receiver to crossover at 150hz, but even I knew that was too high.

    Ok, one more related question. In order to keep my neighbors in the next condo from killing me, I'm putting the sub on the opposite wall from the mains. At frequencies near 100hz is any of the bass directional? Will it seem like it's coming from the wrong place?

    Thanks.

    Donald
     
  9. Lew Crippen

    Lew Crippen Executive Producer

    Joined:
    May 19, 2002
    Messages:
    12,060
    Likes Received:
    0
     
  10. Jack Shappa

    Jack Shappa Second Unit

    Joined:
    Jan 24, 2003
    Messages:
    411
    Likes Received:
    0
    Hey guys, thanks for the education! I realized cross-overs were on a slope, and that there was some "spillage", but I had no idea the roll-off could go as far in either direction. I thought it was much less, and stand corrected.

    - Jack
     
  11. Clem

    Clem Agent

    Joined:
    Oct 11, 2003
    Messages:
    33
    Likes Received:
    0
     
  12. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
     
  13. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0


    If, and only if, you have sub set to NONE.
    I know Bob knows this, but important element to note.

    -V
     
  14. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
     
  15. Donald_S

    Donald_S Stunt Coordinator

    Joined:
    Oct 19, 2003
    Messages:
    103
    Likes Received:
    0
    I appreciate all the input and clarification, but no one has yet answered my second question. With a crossover at 100 hz, and my sub on the opposite wall from my mains, will the sound seem to be coming from the wrong place? As it's been explained here, there will be some sound coming to the sub above 100 hz. Will there be enough that I'm going to have a directional problem?

    Thanks,

    Donald
     
  16. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    I dont know if you will have a "Directional Problem" putting the sub at the rear. But if you concentrate, it IS likely you will be able to determine where the sub is located.

    It is a bit of a myth that "Bass is directionless".

    It IS true that we are much less sensitive to bass frequencies. And a subwoofer generates a LOT of sound from wall-reflections rather than direct.

    Both of these mean you are "less likely" to be able to locate the subwoofer in the room. This has led to the myth that you "...SHOULD not be able to tell where the bass is coming from". - more attitude than fact.

    Most people do find they prefer the sub up-front with the rest of the speakers. You do feel the sound waves and while not as directional as the mid-range/tweeter sounds, you do get a sense of location. (Kind of like wind - you can tell the rough direction of a breeze, but it's hard to pin-point.)

    Donald: you want to know if 80 or 90 or 100 hz crossover would make it less-likely someone could tell the sub is behind them. I'm afraid there is no magic number. I can tell you that 'lower is better', but it's more important you not have a hole between your sub and front speakers.

    I'd set the crossover in the 70-80 hz range and try it for a while. This is far enough above your speakers low-end, but low enough that directional issues may not be a problem.

    But wall reflections- this will have a bigger impact to 'directionality' than crossover.
     
  17. John Garcia

    John Garcia Executive Producer

    Joined:
    Jun 24, 1999
    Messages:
    11,571
    Likes Received:
    24
    Location:
    NorCal
    Real Name:
    John
    Simply adjust the sub by ear until you minimize any directionality, if you even have it at all. You MAY have phasing problems with the mains, depending on room, but you should be able to adjust that on the sub as well.
     

Share This Page