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Advice on my build, please.

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  • Advice on my build, please.

    I was considering ordering very soon. However, the EMM-6 microphone is out of stock :( .. So, I need to wait for that.

    Regardless,

    I am concerned about my build. The woofer I chose, 5.25" - gives an F3 of 80Hz.
    And I plan to use minidsp to quickly kill my actual subwoofer between 60-70Hz, so these speakers won't be backed up much by the sub.
    ( I was considering a 6.5" woofer. But, the cabinet for that is just plain huge. And, the 5.25" gives better off-axis. Moderately important for my seating)

    Sure, I know that means I lose every thing from about 60-80 or 65-80.

    But, my question for you, much more talented gentlemen:
    If the room gain does not bring 65Hz within -3dB, can I do it some other way? Can I use electronics for a slight boost from 90Hz-60Hz? .. Can I use BSC to get good results? etc.

    What Would You Do, with this driver, to fill this gap?


    Thanks.

    (These are my Rear speakers. I'm building them to get experience, for when I do my 3-way.)



    ALSO, do I have decent drivers selected? I expect to cross @ 1.8-2.0

    http://www.parts-express.com/pe/psho...umber=264-1040
    http://www.parts-express.com/pe/psho...umber=264-1078
    An apostrophe with an "s" does not mean plural.

    Speaker's IS NOT PLURAL.

  • #2
    Re: Advice on my build, please.

    Hello icor,

    I like this woofer a little better for your application: http://www.parts-express.com/pe/show...number=264-850
    Reasons:
    1. Smaller box options, vented, will get you a -3dB of 60hz
    2. More dynamic reach within your desired passband.
    3. Easier to flush mount.
    4. Better looking.

    I like this tweeter a little better in the same price class: http://www.parts-express.com/pe/show...umber=264-1028
    Reasons:
    1. Built in wave-guide to reduce baffle diffraction.
    2. Wave-guide should improve polar response transition from midbass to tweeter. (slightly)
    3. Smaller diameter faceplate allows for tighter driver spacing. (better vertical off-axis characteristics)

    -------

    That said, the drivers you have selected can work just fine, I'm not sure why you are concerned about the -3dB @80hz (in I am assuming a sealed box) as that will put you right at about -6dB at the ~65hz x-over, which is fine. Some system tweaking to force some overlap would correct for this, but even moreso, you could just vent the cabs and extend that F3 down to below 50hz if you are really concerned about it. For rear speakers in a surround system a few dB lull in upper bass is unlikely to be noticeable anyways.

    Regards,
    Eric
    Pro/Fi Cinema Speaker project: "From the Ashes"

    Comment


    • #3
      Re: Advice on my build, please.

      icor 1031,
      I don't know anything about the woofer you've selected, but I can speak for the TangBand woofer mdocod recommended. I completed a build with one a couple of weeks ago and am amazed at how sharp and pleasant it is.
      http://techtalk.parts-express.com/sh...d.php?t=226577
      I would really like to do another build with it, but maybe an MTM or TMM. The only area I can say is not great is that it needs a little more power and volume before it really comes to life, thus the addition of a second one.
      Just my 2 cents.
      Mike

      PS- great screen name! <><
      "We're speaker geeks, not speaker nerds. Nerds make money!" Marty H
      Bismarck, North Dakota
      My Current System: Jolida SJ502A, Squeezebox Touch, and Carmody Sunflowers
      My Garage System:Marantz 2238B and Nano-Neos

      Comment


      • #4
        Re: Advice on my build, please.

        Originally posted by icor1031 View Post
        As a general rule of thumb, you want to crossover a tweeter at least an octave above it's Fs. But every "rule" is subject to debate, and I admit that I've made exceptions to this rule.

        You said that you were thinking 1800Hz to 2000Hz... just keep in mind:

        Vifa BC25TG15-04 --> Fs of 1130Hz. (XO normally about 2300Hz minimum)

        Vifa BC25SC06-04 --> Fs of 1350Hz. (XO normally about 2700Hz min.)

        With that said, you could probably go ahead with your plans and it wouldn't really be all that bad... it's just nice to know which rules we're breaking and proceed with some reasonable assurance that it's going to work out ok.
        ~Marty

        Baby Eidolons
        Sapphos
        Cables (Post #54)
        Other speakers (Post #21)
        Design Thoughts (Posts: 6,10,13,33,35)
        Boundary Augmentation
        Dispersion/Interference

        Comment


        • #5
          Re: Advice on my build, please.

          The BC25S/TG can be used to 1800 or so with a 3rd order electrical plus zobel.
          Don't listen to me - I have not sold any $150,000 speakers.

          Comment


          • #6
            Re: Advice on my build, please.

            If the speaker in question will ALWAYS be used with the subwoofer, then I would suggest a sealed box design with Qt=.707. This should reduce your box size. A sealed box has second order behavior like a raw driver. You can use your existing design software to plan the subwoofer crossover.

            Once your satelittle is done, then use the sealed box Fs and Qt as if it was a standard closed back midrange driver. This will make it easy to get smoother integration between your subwoofer and your satelittle.

            Comment


            • #7
              Re: Advice on my build, please.

              I've used that woofer with the nd28. It's a fantastic mid/woofer. Very smooth off axis. Very easy to mount cause it doesnt require a recess. Highly recommend. Only issue is looks. Not the nicest looking thing.
              https://www.youtube.com/channel/UCm2...oSKdB448TTVEnQ

              Comment


              • #8
                Re: Advice on my build, please.

                Hi Jonny,

                A 3rd order network has no need to incorporate impedance correction unless it is for the benefit of an amplifier with special needs (my way of saying a "retarded amplifier"), and furthermore, a zobel does not correct for the impedance rise at Fs that effects the tweeter leg of an x-over anyways. Assuming a modern amplifier without special needs, the only reason I can think to use a "zobel" like circuit on a tweeter would be to shape upper frequency response, at which point it would not be called a zobel because it's purpose would be different.

                ------

                Hi moron,

                The room will have more effect in this frequency range than you can hope to correct for by predetermining a box design for someone elses room. I believe the better approach is to have more dynamic headroom available in the desired pass-band such that if the room is swallowing up some response, it can be injected back in with some EQ with less chance of running out of speaker.

                Regards,
                Eric
                Pro/Fi Cinema Speaker project: "From the Ashes"

                Comment


                • #9
                  Re: Advice on my build, please.

                  I really like the BC25S/TG tweeters, and that is a great budget tweeter choice. I haven't used a peerless woofer in years, so I can't comment on that one at all.

                  Re: The XO point on the BC25TG: In my experience, while they can "handle" an XO under 2k and even as low as 1700, they don't like any volume at that point. When I crank up my Bento's, I can here some serious compression on the tweeter and its crossed at about 1800 LR4. I somehow doubt that will matter in this application, given the woofer choice though.
                  Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                  Sites: Jupiter Audioworks - Flicker Stream - FRD Consortium Archive - Proud Member of Midwest Audio Club

                  Comment


                  • #10
                    Re: Advice on my build, please.

                    Originally posted by mdocod View Post
                    Hi Jonny,

                    A 3rd order network has no need to incorporate impedance correction unless it is for the benefit of an amplifier with special needs (my way of saying a "retarded amplifier"), and furthermore, a zobel does not correct for the impedance rise at Fs that effects the tweeter leg of an x-over anyways. Assuming a modern amplifier without special needs, the only reason I can think to use a "zobel" like circuit on a tweeter would be to shape upper frequency response, at which point it would not be called a zobel because it's purpose would be different.

                    ------

                    Hi moron,

                    The room will have more effect in this frequency range than you can hope to correct for by predetermining a box design for someone elses room. I believe the better approach is to have more dynamic headroom available in the desired pass-band such that if the room is swallowing up some response, it can be injected back in with some EQ with less chance of running out of speaker.

                    Regards,
                    Eric

                    I don't understand Eric.
                    How would you design the crossover between satellite and sub?

                    Comment


                    • #11
                      Re: Advice on my build, please.

                      Originally posted by icor1031 View Post
                      I was considering ordering very soon. However, the EMM-6 microphone is out of stock :( .. So, I need to wait for that.

                      Regardless,

                      I am concerned about my build. The woofer I chose, 5.25" - gives an F3 of 80Hz.
                      And I plan to use minidsp to quickly kill my actual subwoofer between 60-70Hz, so these speakers won't be backed up much by the sub.
                      ( I was considering a 6.5" woofer. But, the cabinet for that is just plain huge. And, the 5.25" gives better off-axis. Moderately important for my seating)

                      Sure, I know that means I lose every thing from about 60-80 or 65-80.

                      But, my question for you, much more talented gentlemen:
                      If the room gain does not bring 65Hz within -3dB, can I do it some other way? Can I use electronics for a slight boost from 90Hz-60Hz? .. Can I use BSC to get good results? etc.

                      What Would You Do, with this driver, to fill this gap?


                      Thanks.

                      (These are my Rear speakers. I'm building them to get experience, for when I do my 3-way.)



                      ALSO, do I have decent drivers selected? I expect to cross @ 1.8-2.0

                      http://www.parts-express.com/pe/psho...umber=264-1040
                      http://www.parts-express.com/pe/psho...umber=264-1078

                      My HT room has 15 dB of gain at 45 hz! A sealed f3 of 80 hz works very well without a sub at moderate spl levels. (I have a sub too, but could get by without it.)

                      Comment


                      • #12
                        Re: Advice on my build, please.

                        Originally posted by moron#99 View Post
                        I don't understand Eric.
                        How would you design the crossover between satellite and sub?
                        I wouldn't have to design anything. For me it would simply be an implementation of pre-existing electronics. A flat performance in the 20-200hz range is a challenge in most rooms, best overcome with adjustable active crossovers and/or EQ controls.

                        The natural rolloff of a sealed box mating to a typical x-over point may be beneficial, or counter-productive to achieving the desired result, you're under the impression that it can only be beneficial.

                        Regards,
                        Eric
                        Pro/Fi Cinema Speaker project: "From the Ashes"

                        Comment


                        • #13
                          Re: Advice on my build, please.

                          I use zobels to flatten out the impedance, so it's easier to get the crossover slope you want with parts that are close to text book, of course I end up with 20 parts to my crossovers, but cost is not really a problem with this build, I just want it to measure well.

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                          Comment


                          • #14
                            Re: Advice on my build, please.

                            I meant to write "L-Pad".
                            Don't listen to me - I have not sold any $150,000 speakers.

                            Comment

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