Dumb BFD question

Discussion in 'AV Receivers' started by John Garcia, Nov 16, 2005.

  1. John Garcia

    John Garcia Executive Producer

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  2. David_Rivshin

    David_Rivshin Second Unit

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    The FBQ2496 is the newer model. As far as I know it came out just a few months ago. As best I can tell it's major improvements are:
    • 20 filters per channel (vs 12)
    • 96kHz sampling rate (vs 46kHz)
    • slightly updated user interface
    Are the changes worth a 50% increase in street price? I'd guess that for subwoofer EQ it really doesn't matter. If you're using more than 12 filters you're probably using way too many. And in theory you only need to sample at 200Hz to properly represent a 100Hz signal, so even 46kHz should be plenty for subs. User interface is personal choice, obviously.

    On the other hand, if I didn't already have a DSP1124P I'd probably buy the FBQ2496, just because it's newer and better, at least on paper.

    Hope this helps,
    -- Dave
     
  3. John Garcia

    John Garcia Executive Producer

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    Thanks. That's what I thought, but wasn't sure if it was just a newer model or if it had any benefits that I would actually want right now, since I do intend to only be using it for the sub. 20 frequencies per channel makes more sense across the entire range, but not for ~200Hz and under, so I'll probably go for the older 12/channel one. I ran a quick response last night and came up with about 4-5 peaks I should probably tame (without correction factors).
     
  4. John Garcia

    John Garcia Executive Producer

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    Next question - does it matter if I use XLR or 1/4" adapters?
     
  5. David_Rivshin

    David_Rivshin Second Unit

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    Do keep in mind that it can take more than one filter to properly treat a peak/dip if it's not symmetric. If you post your response curve in the speakers+subs forum I'm sure someone will suggest some filters to start with. I think there's even an Excel spreadsheet out somewhere to auto-guess them as a starting point.

    If you don't have balanced sub output from your receiver or preamp, then it doesn't matter at all. If you do have balanced output then balanced connections can make a difference if you're running long distances. For under 10 feet or so I wouldn't worry about it.

    BTW, the 1/4" jacks on the FBD's are actually balanced as well, which is why you have to use mono RCA->1/4" adapter plugs. Otherwise you'll end up tying the + and - signals together, instead of the - and ground signals, and end up with no output.

    -- Dave
     
  6. John Garcia

    John Garcia Executive Producer

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    Thanks again. I don't have balanced connections on the sub or recevier so... I'd already found mono 1/4" -> RCA adapters at PE, where I plan on buying the BFD, and figured that's what I would go with because they aren't that expensive.

    I'm going to try to get my response charted this Sun. Where can I get the Rat Shack analog SPL meter correction factors?
     
  7. Wayne A. Pflughaupt

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    John,

    Instead of the adapters, why not just get the some cables with the correct ends on them, like these:


    [​IMG]


    These are from Musician’s Friend, but I’m sure PE has them somewhere on their site. Not that you’ll get dramatic improvement in SQ or anything, but the adapters are just a cheesy way to do things, IMO. Kinda like wrapping a splice with electrical tape.


    Here are 1/6-octave correction factors for the sub frequencies.

    16Hz +11.5
    18Hz +8.0
    20Hz +7.5
    22Hz +6.5
    25Hz +5.0
    28Hz +4.0
    31.5Hz +3.0
    36Hz +2.5
    40Hz +2.5
    45Hz +2.0
    50Hz +1.5
    56Hz +1.5
    63Hz +1.5
    71Hz +1.5
    80Hz +1.5
    89Hz +1.5
    100Hz +2.0
    111Hz +1.0
    125Hz +0.5
    142.5Hz +0.5
    160Hz -0.5

    Regards,
    Wayne A. Pflughaupt
     
  8. John Garcia

    John Garcia Executive Producer

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    I thought about those because I think I had seen you post about them a while back on another BFD thread, but the adapters will actually only run me about $4 for a pair and I will use spare RCAs that I have now.

    These look pretty solid to me:
    [​IMG]

    Thanks for the correction factors. Looks like my problem is even worse, since those guys are ADDING to my hump.
     
  9. David_Rivshin

    David_Rivshin Second Unit

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    Personally, I use Belden 1694A for all my A/V interconnects, and since I like to crimp my connections (don't trust my skills with a soldering iron enough to get consistently good results), I terminate with these:
    [​IMG]
    For my BFD I then just stick on those same RCA->1/4" mono adapters from PE. It'd be hard enough to find good 1/4" plugs which can fit RG6 into them, but I don't think I've even ever seen any that are crimp on.

    -- Dave

    PS. I think I have to run off now and wrap the joint between the connectors in electrical tape [​IMG]
     

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