Newbie subwoofer setup questions (Cleanbox vs BFD vs EQ)

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  • impala454
    Ultra Senior Member
    • Oct 2007
    • 3814

    Newbie subwoofer setup questions (Cleanbox vs BFD vs EQ)

    I have a pretty hefty bandpass box with two 10"s that I'm currently using for my sub. It's a box mostly meant for car audio competitions but right now it's filling in for HT duty until I get something else built. It has two 4Ω drivers and I can wire them however I need to (they are arranged in push/pull). Anyhow, I was powering it with an A500 (source from pre-amp outputs of a Denon 2307CI). I knew this box could handle a lot more power so I grabbed an EP2500. So now the chain goes Denon -> RCA mono -> 1/4 TSR -> EP2500. It seems I had to crank the gain on the sub output to +12dB (max) to get the sub to some good output at about 12 o'clock gain on the EP2500. Probably obvious to most on here, but it doesn't sound that great.

    So here goes my questions:

    1. I've heard of people using a cleanbox to "step up" the pre-amp signal to pro sound levels. I've read a lot and there seems to be pros and cons (read where a lot of people got them, then removed them later). Would something like this help? Or is it no better than jacking up the gain on the receiver?

    2. I've heard of people using a BFD. I've also read a lot about these, but honestly don't really understand what it does. Does it also step up the gain? If I was to get one, what exactly would I do with it straight out of the box?

    3. I've heard of people using an EQ (with several different models given). Without hooking up a mic and graphing everything (which I've never done before) I can definitely tell there are gaps in the curve. I.e. I loaded up the star wars II opening scene with the big chrome B2-bomber-looking ship coming down and one part would be booming to the point of bringing down the house (as it should be :twisted: ) but another part would be pretty disappointing. Would an EQ help me level this out, and solve the gain problems from the consumer -> pro equipment? Would an EQ also replace the BFD or cleanbox (kind of an all in one)?

    4. Is there some other box I should be aware of that I didn't list?

    5. Should I wire the subs a certain way for better performance? As said they are two 4Ω 10"s in a push/pull config in a bandpass box (box is here if you want to see it). I suppose my options are:
    a. One driver straight to each channel on the amp and run in parallel mode.
    b. Parallel the drivers for a 2Ω load and just run off one amp channel (read that 2Ω -> bridged mono is a big nono on this amp)

    6. I can set my sub crossover frequency in my Denon, should I just set that as high as possible and let one of these boxes do the rest, or what should I set it at?

    Sorry if any of these questions are just rehashes of old threads. I did read through a lot of them, and being extremely new to these three pieces of equipment, there was lots of stuff over my head in those threads. Plus I figured for some newbie who comes along after me he'll have all three in the same thread .
    -Chuck
  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10933

    #2
    Originally posted by impala454
    So now the chain goes Denon -> RCA mono -> 1/4 TSR -> EP2500......but it doesn't sound that great.
    That's because it should be a 1/4" TR not TSR

    As for the rest of it start reading here....

    IB subwoofer FAQ page


    "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

    Comment

    • impala454
      Ultra Senior Member
      • Oct 2007
      • 3814

      #3
      Oh oops I might have used the incorrect lingo. This is the adapter I got: http://www.partsexpress.com/pe/pshow...umber=091-1010

      Awesome looking info on that writeup, I will read it over asap. Thanks!
      -Chuck

      Comment

      • Dennis H
        Ultra Senior Member
        • Aug 2002
        • 3798

        #4
        It seems I had to crank the gain on the sub output to +12dB (max) to get the sub to some good output at about 12 o'clock gain on the EP2500
        Turn the gain all the way up on the EP2500.

        Comment

        • impala454
          Ultra Senior Member
          • Oct 2007
          • 3814

          #5
          Originally posted by Dennis H
          Turn the gain all the way up on the EP2500.
          And then turn the gain on the sub pre-out down? I guess I was worried that it'd be putting too much power through the sub.
          -Chuck

          Comment

          • Brian Bunge
            Super Senior Member
            • Nov 2001
            • 1389

            #6
            Yes, turn the gain all the way up on the amp and then use the sub out adjustment to calibrate the sub.

            Comment

            • Dennis H
              Ultra Senior Member
              • Aug 2002
              • 3798

              #7
              The gain control on a pro amp is really a cut control. It's a pot that reduces the input signal but never boosts it above unity gain. It's there for pro mixers that may put out as much as 10V but it's not needed for consumer gear that only puts out about 1V. Turn it all the way up to match the output of a receiver.

              Comment

              • kingpin
                Senior Member
                • Jun 2006
                • 958

                #8
                Regarding the Cleanbox. Did I read somewhere that it was tested by someone and it was found to roll off too quickly to be used for a sub.
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                Comment

                • bonehead848
                  Junior Member
                  • Apr 2007
                  • 18

                  #9
                  Originally posted by kingpin
                  Regarding the Cleanbox. Did I read somewhere that it was tested by someone and it was found to roll off too quickly to be used for a sub.
                  Last edited by ThomasW; 14 June 2008, 17:39 Saturday.

                  Comment

                  • impala454
                    Ultra Senior Member
                    • Oct 2007
                    • 3814

                    #10
                    ouch... so even to my semi-untrained noobish eye, that's pretty bad eh?

                    Ok so I've gone over ThomasW's awesome informative website on EQs and such. So am I correct in thinking that the BFD will essentially match my Denon's subwoofer pre-out by pushing in the "Operating Level" switch to match it to the -10dB setting? I do this, then adjust the Denon's output to get the signal levels on the BFD in the green, and everything will be koombaya and set for me to start setting filters to fine tune?
                    -Chuck

                    Comment

                    • collo
                      Member
                      • Nov 2005
                      • 67

                      #11
                      Correct.

                      That's exactly what I did. AV amp -> BFD (-10 setting ) -> EP2500 ( Max gain ). Works a treat!

                      Thomas' guide's are the best out there. You can't go wrong with 'em...
                      Ports rule ...

                      Comment

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