Quick BFD question

Discussion in 'Archived Threads 2001-2004' started by Craig Woodhall, Jun 11, 2002.

  1. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Was gonna pick one up and I have two tempests (one running off each channel of a Mackie FR-1400).. Can it eq both subs independently (like stereo) or would the eq settings be applied to both the subs.. Sorry if this sounds like a newbie question, cause I aint.. [​IMG]
     
  2. Jeff PB

    Jeff PB Agent

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    It can equalize both independently
     
  3. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Well that was quick and precise.. Thank you, sir!

    Craig
     
  4. Kyle Richardson

    Kyle Richardson Screenwriter

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    Jeff, how exactly would you do that? Would you send one sub signal in the L and one in the R? If so then how would you configure the front of the BFD? You wouldnt want to couple the engines would you?
     
  5. brucek

    brucek Second Unit

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    Kyle,

    In couple, both left and right channels would have the same filter data. The couple mode is a convenience for the user who knows he wants to have the same data in both channels and doesn't want to have to enter it twice.

    If you turn couple off, then you have to enter your filter data seperately into both left and right channels....

    brucek
     
  6. Kyle Richardson

    Kyle Richardson Screenwriter

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    Thanks Bruce. I'll be adding a second sub in the future so I'll just ucouple it and adjust one of the other channels for the new sub.
    Cool[​IMG]
     
  7. Craig Woodhall

    Craig Woodhall Supporting Actor

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    That is what I was wondering.. You wouldn't want to apply the same filters to both subs unless they were the same sub in the same position because each sub would interact with the room differently..
    Bruce, great job on the BFD setup guide, I will be printing the 20 pages today.. Thanks for saving me a bunch of time and frustration, much appreciated..

    Craig
     
  8. brucek

    brucek Second Unit

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    Craig,
    Yeah, that's Sonnie Parkers site. He did a very nice job and put a lot of work into it. I just contributed a few articles.... [​IMG]
    brucek
     
  9. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Hey guys, im going to pick it up on Friday but the guy said that it didn't have a power cord.. Do you guys know where I can get a power cord for it? Is it just a standard computer cord? Thanks in advance.

    Craig
     
  10. Kyle Richardson

    Kyle Richardson Screenwriter

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    Mine came with a cord...dont know why yours wont. If it doesnt then its just a standard plug.
     
  11. brucek

    brucek Second Unit

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    Geeez Craig, what kind of a place are you buying this device at, where they can't come up with a power cord?

    Either way, it draws negligible current, so you can use any cheesy three prong computer cord around....

    brucek
     
  12. Craig Woodhall

    Craig Woodhall Supporting Actor

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    I bought it used but in mint condition off ebay.. He didn't have a powercord/box/or manual.. But the good news is, I got it for $160 CDN and it is local so, no taxes, no shipping.. Thanks guys..
    Craig
    ps. now I just need two of the new 15" Adire drivers [​IMG]
     
  13. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Bruce,(or anyone)

    Quick question.. I was reading the setup instructions again and got to the part with input level setup of the BFD. I understand how to do this by adjusting my subwoofer level from my Lexicon DC-1.. Once I have the input level set right for the BFD and do all my eq'ing, i understand that I don't touch the sub level on the lexicon again because that would screw up the input level to the BFD, but how would I go about calibrating the sub to the rest of my system? it says use the volume control on the sub but since I use a Mackie FR-1400 with the gains all the way up how would I do that if the sub was a little low and needed to be raised to be calibrated properly? Sorry for the rambling, just trying to make sense of it all.. Thanks guys.

    Craig
     
  14. Kyle Richardson

    Kyle Richardson Screenwriter

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    I would still keep the gains on the Mackie up full and adjust the Lexicon sub out. I have my sub output turned up to the point that I don't know if I've ever seen a yellow LED but I'm still getting plenty of output for the sub amp.
    Also to get it to the point that I would see yellow LED and the occasional red LED I had to turn my sub output on my receiver (Outlaw 1050) to about +8 out of 10. I didnt want to drive my sub output this hard and cause distortion so I just dropped it back down to +4 (still high for my taste) and turned my sub amp up a bit to compensate (plate amp not pro amp where you want the gains up). I get the green LED's about 3/4 the way up on loud bass scenes at this setting.
    Anyway, I didnt really notice an audible difference so thats the setup I went with. Clear as mud?
     
  15. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Kyle,
    about as clear as my post [​IMG] .. Thanks for the quick response, it is much appreciated.. That does make sense..
    Also, Kyle, let me know if you hear anything about the pre-order on the new 15" woof from adire..
    Craig
     
  16. brucek

    brucek Second Unit

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    Craig,
    I think it's best to have the input to the BFD set up to an optimum level, and then if that's not enough to drive a pro level amp, then you should add a line driver like the Black Box that SVS sells for that exact purpose.
    The best place to insert the line amp would be between the BFD and SVS power amp for several reasons. Feeding the line amp from the processor is not a good idea.
    The BFD is not an amplifier, it's a unity gain device. Since it's digital and you're feeding an ADC/DAC chain you want to optimize its input level to take advantage of all the bits available. By this I mean to take maximum advantage of the dynamic range provided by the analog to digital converter in the BFD or any ADC for that matter, you need to provide it with a maximum input signal level that takes advantage of the greatest number of bits to represent the resultant voltage samples.
    If the range from your weakest signal to the strongest signal was only half the required maximum input level, you would be robbing yourself of dynamic range and subsequently increasing your signal to noise level. To get the most out of this system you would like the maximum signal sent to the BFD to "just" not turn on the red LED. If the yellow LED comes on in explosions etc, that would be fine. The BFD has no compressor or limiter on its input, so you can easily overdrive it and clip the output.
    This means once you've reached and set this level, you can't increase the level any more even if you wanted to. So it's the output analog signal that you want to amplify, and not the input signal which is easily set to optimum by your processor.
    The BFD's unity output (or less if filters are applied) can then be amplified to your hearts content with the line amp. If the line amp can create 15dB gain, then it will "all" be available to you, instead of being limited if you placed the line amp before the BFD.
    Getting 3/4 of the Green LED's on loud scenes (as Kyle has stated) would probably be OK, but full scale would be optimum. You may want to consider an amp [​IMG]
    brucek
     
  17. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Thanks Kyle and Bruce, I can always count on my HT buddies!
     
  18. Craig Woodhall

    Craig Woodhall Supporting Actor

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    I just took some initial measurements and put them into the Excel spreadsheet. How can I export my graph from within the spreadsheet so I can post it for your guys comments and suggestions.

    Craig
     
  19. Jim J

    Jim J Second Unit

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    Going down this road myself.
    I just took screen shots in Windows ALT+{print screen}
    Then I pasted into Paint. You can trim off the stuff you don't need easily. You can see my start here http://home.earthlink.net/~juliano1437/ht/
     
  20. Craig Woodhall

    Craig Woodhall Supporting Actor

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    Thanks Jim, that worked great, now I just need to figure out how to post them..

    Craig
     

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