Sub Crossover & DD. How is it Used?

Discussion in 'Archived Threads 2001-2004' started by Jason Wolters, Dec 20, 2001.

  1. Jason Wolters

    Jason Wolters Stunt Coordinator

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    What role does the sub cross-over play while listening to Dolby Digital 5.1? If I have my sub set to 60 hz. and my mains set to small, where do the high-passed frequencies go? Does the crossover effect LFE the same as other bass?
     
  2. Bob Christensen

    Bob Christensen Stunt Coordinator

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    The LFE channel will be feeding only the lows anyway, and it is a dedicated channel, so the sub's XO will have little effect, and probably a negative effect. If you can, bypass the sub XO for DD.
     
  3. Jason Wolters

    Jason Wolters Stunt Coordinator

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  4. Barry BB

    Barry BB Stunt Coordinator

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    With sub crossed over at 60hz above 60hz goes to mains and below goes to sub. But if you have your receiver crossed over at the typical 80hz you may have a gap. If your sub does not have a cut off then just set the cross over to the max.
     
  5. Jason Wolters

    Jason Wolters Stunt Coordinator

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    So I guess I will assume that the LFE will be treated the same. Any LFE below 60 hz passes to sub. Above goes to mains? Correct? LFE is a brick wall. Correct?
     
  6. Vin

    Vin Supporting Actor

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  7. JohnRice

    JohnRice Lead Actor

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    Jason,

    The basic idea is that you don't ever use two crossovers in line. This is referred to as cascading crossovers and can cause any number of problems. Your DD receiver has it's own sub crossover and you should use it ONLY. Hopefully your sub lets you bypass it's own crossover, if not set it to the highest frequency.

    If your main speakers are set to small, their lower frequencies should be routed to the sub along with the LFE.
     
  8. JohnRice

    JohnRice Lead Actor

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    Vin,

    I think you mean, some receivers will allow the deep bass for speakers set to LARGE to be sent to BOTH the mains and the sub.
     
  9. Jason Wolters

    Jason Wolters Stunt Coordinator

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    I have a little Aiwa 8" sub. My mains are Pioneer floor speakers with 12" woofers. I am thinking about setting the mains to large and raising the crossover frequency to 80 hz. Right now with my RX set to small all frequencies below 100hz are routed to the sub, where they are apparently cut off at anywhere from 60-100hz depending on the setting. With the setting to Large all frequencies below the cutoff will be redirected to the mains and the sub will continue to get the LFE at least below the cutoff. (i can't shut it off)Is this right?
     
  10. Barry BB

    Barry BB Stunt Coordinator

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    I don't know how good your sub is so the following may need to be tweaked.

    Don't get caught up in your mains being big towers so that you set them to large. You should set your mains to small and your sub crossover to maximum. If your receiver has an 80hz crossover set it to 80hz instead of 100hz. Any deep bass (not LFE) below your receiver's crossover setting will be directed to your sub. You want your sub crossover to be maxed to eliminate bass being directed back to your mains by the sub's crossover setting.

    LFE is a separate channel so all LFE will go to your sub.
     
  11. Jason Wolters

    Jason Wolters Stunt Coordinator

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    My sub quality is low in my opinion. It is an 8" Aiwa active with 60 watts of power. My thoughts are to set the mains to Large so all frequncies below receiver's 100 hz crossover range will be redirected to the mains. Otherwise in the normal mode everything below 100hz will be redirected to the sub. The sub will start blocking all frequencies above 80 hz. So there is a gap in the 80 to 100 hz range. I will still get the LFE below 80 hz via the sub. I can't shut off my sub.
     
  12. Vin

    Vin Supporting Actor

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  13. Bob Christensen

    Bob Christensen Stunt Coordinator

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    The only time that I would use the sub's XO is if you are feeding the sub's amp a full frequency signal, and are running your sat's from the sub, instead of the amp. Do NOT run double XO (receiver AND sub). It will not be good. As far as setting your speaker size in your receiver menu, I would recommend trying each and seeing what sounds better to YOU.
     
  14. BruceD

    BruceD Screenwriter

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    Jason,

    I don't think you are quite getting this bass thing. So how about supplying some more information?

    1)What controls are on your Aiwa sub, and what crossover frequencies?

    2)What receiver do you have?

    3)Exactly what are the receiver's bass management options?

    4)What is the receiver's selection of Crossover frequencies?

    5)Do you have Bass to Sub-out and Mains (if Mains are Large)?

    Then maybe we can give you some more advice on how to adjust.

    BruceD
     
  15. Jason Wolters

    Jason Wolters Stunt Coordinator

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    Bruce,

    1. Aiwa controls on the sub....On/Off 60,80 and 120 hz crossover. Can't shut it off.

    2. Kenwood VR507

    3. Large/Normal Sub On/Off

    4. No selection of crossover frequencies on receiver

    5. Unsure of question?

    Here is my understanding of bass management.> All speakers that are set to Large will get a full range of frequencies. All speakers set to Normal will send frequencies below the cutoff at the receiver to the sub.(I am unsure of my cutoff frequency). LFE will always go to the sub.

    So based on that I set my mains to Large. I did this because I feel that my mains can handle the frequencies below the cutoff better than my sub. My sub will still get all of the bass from the other channels as well as getting the LFE.
     
  16. BruceD

    BruceD Screenwriter

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    Jason,

    Great.

    Since you think maybe the Aiwa can't handle all the re-directed bass from the other speakers plus the LFE (might be a good assumption), setting the mains to Large might be a good idea. I'm assuming the sub is plugged into the receivers Sub-out jack.

    If the receiver is THX certified, then it's xover should be 80Hz, if not then it could be 100Hz.

    My recommendation is to set the subwoofer's xover to 120Hz (highest possible) so it doesn't interfere/interact with the receiver's crossover.

    If you set the subwoofer's xover the same as or below the receiver's (@80Hz or @60Hz) then you will have what is called cascading crossovers (this is bad).

    After listening with Large mains for a while, you can also try setting the mains to Normal as an experiment and see how the Aiwa sub handles all the bass. This might require re-calibrating the speakers.

    Question #5 means some receivers give you a setting to send all the re-directed bass + LFE to the sub AND Large mains at the same time.

    BruceD
     
  17. Richard_Wg

    Richard_Wg Extra

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  18. BruceD

    BruceD Screenwriter

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    Richard,

    You should start a new thread and ask this question of everyone here on the board. I'm sure you will get a lot of answers.

    Bass Management to Sub and Mains Simultaneously?

    I don't own a receiver (I have a pre-pro) so I don't remember which models do and which don't.

    BruceD
     
  19. James Herrod

    James Herrod Stunt Coordinator

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    Okay I don't know if this makes a difference, but my DD and DTS decoder is on my DVD player, not my receiver. I do the bass management through the player and I have my mains set to small. My 8" sub has a high cut filter that ranges from 50 to 120 hz. My question is; in this situation would I set my high cut filter to max and would this let the XO on the DVD player take over? I'm assuming that XO would also be 80 hz. Thanks

    Jim
     
  20. BruceD

    BruceD Screenwriter

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    Jim,

    If your assumptions about an 80Hz xover on the DVD is correct, then the sub internal xover set to 120Hz is best (only if you can't turn the sub's internal xover OFF altogether).

    BruceD
     

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