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Sub calibration - a few questions

Discussion in 'Speakers' started by Corey K., Apr 28, 2005.

  1. Corey K.

    Corey K. Auditioning

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    I've posted this on two other sites, so if you've already read it, I apologize...

    I've EQ'd my sub with the BFD to the point I'm currently at; I've needed about 5 filters to get to the point I'm at. But I have a few questions, I'm hoping somebody out there might have the answers:

    It doesn't seem that cutting the hz at frequencies over 80hz has a measurable impact at all. I've got a filter at 97 hz to cut the output by about 10 hz; the result is no different than before I put the filter in. So the crossover in my receiver is set at 80hz, and I know it doesn't just cut off there, but rolls off from that point on up. So the question is, at the frequencies above 80hz, is there any way to use the BFD to smooth things out, considering only my subwoofer is connected to it? In other words, after 80hz, the main speakers begin to put out a progressively larger proportion of the sound relative to the subwoofer, so it seems that there is no real way for me to fix this.

    One more question. Would it be helpful to do the measurements with the main speakers shut off (sub only) as well as the sub shut off (mains only)? I'm thinking they all need to be on as that's how I'll listen to movies.

    Also, would there be any benefit to raising the xover to 100hz, to allow me access to flatten things out above the 80hz level?

    Any help with these questions would really be appreciated; I'm kind of at a stopping point for the moment. Thanks very much.
     
  2. John S

    John S Producer

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    I wouldn't go over 100hz as the sub will start to localize. But moving up the xover taxes the sub more, and the amp/speakers less. Only when the main system is really poor do I go to like 120hz.

    By the inverse, when a system is really good like my own, I tend to move the xover lower to like 60hz and let my speakers handle some of the bass they can effectively.
     
  3. Corey K.

    Corey K. Auditioning

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    Well, my receiver only goes down to an 80hz crossover. Would I be better suited to leave that at 80hz, and set the xover control on the sub to 60hz, or would that not benefit me at all (assuming my other speakers can handle the bass)? Would doing this really even direct any more low frequencies to my other speakers, since the receiver xover is fixed at 80hz?
     
  4. RyanJE

    RyanJE Second Unit

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    Dont do that. It you set your AVR at 80hz and your sub at 60hz your going to be missing everything between 80-60. It would be a double filter. If your using your AVR's x-over you should turn the knob on your sub all the way up. Doing this elimantes the function of your subs X-over and uses the AVR x-over.
     
  5. Corey K.

    Corey K. Auditioning

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    OK, that's how I've got it set up currently. I guess that brings me back to my original questions then...
     
  6. Max F

    Max F Second Unit

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    My system does the same thing. I decided to live with it. The mains have some peaks and dips in the bass response.

    You could EQ the mains and there is another Behringer product that can do it digitally (i don't have the product number in front of me), but I think you can only do 2 channels (won't help you on multi-channel). Also, i think you would have to have digital output into it from the CD player and then output from it to the receiver. Anyway, there ways to do it - do a search on Behringer.

    I basically decided that things sounded pretty good on my system and gave up obsessing about EQ'n the mains. Just enjoy it. EQ'n the sub is definitely worth it though.
     
  7. Carl P

    Carl P Extra

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    Re-read original post and edited.
     
  8. Max F

    Max F Second Unit

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    Does that mean you like the way it sounds?
     
  9. Corey K.

    Corey K. Auditioning

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    You lost me on that one...
     
  10. Clinton McClure

    Clinton McClure Casual Enthusiast
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    This brings up a question. My receiver (Yamaha RX-V995) has a set LP x-over @ 80Hz and my sub (Paradigm PDR-10) has a variable x-over from 50-150Hz. Right now I have the sub's x-over set to 150Hz and I'm using my BFD to EQ from 16Hz to 160Hz.

    If my receiver is filtering out LFE below 80Hz and sending it to the sub and the sub is set to wide open, accounting for the x-over slope, do I really need to EQ my sub above 80Hz?

    As a brief aside, before EQing it, when I would calibrate the sub using Video Essentials, @82dB the volume knob was a bit less than halfway up. After EQing it with the BFD, I can run the test tones from Video Essentials and I'm reading
     
  11. Corey K.

    Corey K. Auditioning

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    I've asked that same question and never really gotten a concrete answer, other than that your receiver rolls off the output as the frequecies climb over 80hz. I've tried to EQ a peak at around 100hz and it had no effect, regardless of how many db I tried to cut it with the BFD. This is because the mains are contributing some of the bass at this frequency, so adjusting my subwoofer made no difference...
     
  12. Max F

    Max F Second Unit

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    Oh i thought you had already figured out that you will not likely be able to EQ (with the BFD) the sub level above (say 90 hz) if you have the reciever filter set to 80 hz.

    You would have to EQ your front speakers if you want to handle those peaks. There is another Behringer product that may be able to do that (its called something like a pro-curve, can't remember). Or get a receiver that has EQ build in

    Here see this link:

    http://www.hometheaterforum.com/htfo...ight=behringer
     
  13. Max F

    Max F Second Unit

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  14. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    If I understand your problem, you have a peak at 97 Hz and are crossing over at 80 Hz, and the BFD filter at 97 makes no difference. Your room is probably reinforcing the energy at 97 Hz from your mains alone such that it would still be too loud there even if the sub puts out nothing. Your options are limited. Room treatments would help. You might try moving the mains if you can- even a few feet might make a difference. Crossing higher would help as mentioned because it would extend the reach of the BFD to those higher frequencies, but may make the sub localizable. Try that- might be a good tradeoff.

    One more thing to try- its a longshot but if your lucky it could work. If your sub has a phase knob or 0/180 switch, see if you can get some sub energy in the room at 97 Hz with a phase that cancils some of the main energy. In that case, paradoxically, a boost on the BFD at 97 could bring down the peak even more.
     
  15. Clinton McClure

    Clinton McClure Casual Enthusiast
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    I thought about it for a couple days and it clicked that EQing above 80Hz (I checked my receiver's manual and it's actually 90Hz for me) is useless.

    I also turned down the output from my cd player by 21dB to get closer to the output level of my DVD player. This allowed me to better fine tune the sub with my BFD using fewer filters and I now have the sub volume at just above 3/4 rather than full up. I still have more critical listening to do, but it's sounding better so far. I'm still trying to squeeze about $500 into my budget this year to get a SVS.
     

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