Drivers for IB/Dipole sub applications

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  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10934

    Drivers for IB/Dipole sub applications

    Welcome,

    On a different forum there was an interesting thread about the types of drivers used for these applications and different loading configurations. The impact the loading configurations have on the operation of the drivers. And what specific drivers are most suitable for IB/dipole applications.

    On that particular forum certain people who are unable to keep their egos in check. So the topic has been restarted here to avoid future problems..........




    theAudioWorx
    Klone-Audio

    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
  • jaakan
    Member
    • Dec 2002
    • 98

    #2
    Mics don't just record the front sound wave but the back wave two,
    like a sign wave.

    DI-poles are push-pull or moving forword than backword like s-wave. BI-poles are two way/mirrored motions front and back at the same time. I can't think of a single Bi-pole driver. Ohm Walsh "Walsh/Can" divers are omni-poles. Planer drivers like Magnepan, which are basicly ribbons, and Quad ESLs, Soundlab, Wraith speakers ( who has a ESL sub ) for example, by design are DI pole drivers/panels.

    Dipole are good for Sound and music reproduction

    Bipole are good for Filling a room with sound

    ex: Def-tech BP3000 speakers ( cones in the front and back )
    double impact/wow factor for movies

    Comment

    • ThomasW
      Moderator Emeritus
      • Aug 2000
      • 10934

      #3
      Hi ,

      Thanks for posting. Guess I should have been just a bit more specific.

      This thread is to discuss which kinds of woofers are appropriate for use in dipole/IB subs.

      Some are advocating 18" pro sound drivers with accordion surrounds. Their contention is that larger pro sound drivers are 'quicker' than drivers like Shiva/Tempest/DLP12/Titanic/PE IB woofer/PE DVC 12/15. Their reasoning is that the drivers I listed above have 'heavier' rubber surrounds and heavier dual VC's. And that as a result of these items, the drivers aren't as 'fast' as an accordian surround pro sound woofer like the Eminence Kappa 18" or the PE Dayton 18" pro woofers.

      What say you all?
      Jon




      theAudioWorx
      Klone-Audio

      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

      • Dennis H
        Ultra Senior Member
        • Aug 2002
        • 3791

        #4
        the drivers aren't as 'fast'
        Ackkkk, gag (making a sign to ward off evil) --- Thomas said the F word.

        Comment

        • Dennis H
          Ultra Senior Member
          • Aug 2002
          • 3791

          #5
          Actually, on a more serious note, I can see the value of pro drivers for IB or dipole WOOFER (not SUBwoofer) applications because the cones typically don't break up as low. If your design goal is to cover the range of 40-300, I've always liked the sound of the JBL 15. Spendy, though.

          Comment

          • JonMarsh
            Mad Max Moderator
            • Aug 2000
            • 15209

            #6
            Yeah, but the JBL drivers aren't optimized for Xmax and LF power output. (I'm an old pro sound guy and ex performing musician, and built a lot of my speaker cabinets and PA gear).

            The large, stiff half roll surrounds are necessary to avoid "suck back" (uh oh, I used the "s" word) in long excursion LF applications (think 20 - 25 mm Xmax woofers at 15 - 20 Hz). Most of the well designed cones for these applications don't get into their first break up mode until above 400 to 600 Hz. Presuming one is using them with an active crossover (in the 50 Hz to 100 Hz range), it's the crossover by far which is limiting the risetime and bandwidth.

            Now, a factor to be considered is that high VC inductance woofers with high Xmax are typicall not flat above 70 Hz, due to the voice coil inductance. So, if you don't equalize the woofer bandpass before applying the crossover, you'll have problems with the amplitude and phase response in the crossover transition; this could be producing the effects that some folks are mistakenly equating with the "speed" of the woofer. :?

            We had very good results and excellent blend with an HE-15 when we peformed accurate nearfield equalization (not room listening position!) to flatten the He-15 from 15 Hz to 150 Hz prior to the electronic crossover, then using an electronic crossover (4th order L_R, modified Marchand XM9) to affect the transistion between the mains and the sub. Beleive me, there was nothing slow about that combination of the Whispers above 80 or 100 Hz and the HE-15 below. :B

            It's important not to confuse performance capabilities with system integration issues arising from ignoring the innate characteristics of the components in the system... :W

            I've seen quite a few cases where people have heard a "difference" or a problem, but been confused or mislead about the true nature and source of the problem. I see this frequently in the course of my work as an applications engineer for power electronics.... 8)

            Best regards,

            Jon




            Earth First!
            _______________________________
            We'll screw up the other planets later....
            the AudioWorx
            Natalie P
            M8ta
            Modula Neo DCC
            Modula MT XE
            Modula Xtreme
            Isiris
            Wavecor Ardent

            SMJ
            Minerva Monitor
            Calliope
            Ardent D

            In Development...
            Isiris Mk II updates- in final test stage!
            Obi-Wan
            Saint-Saëns Symphonique/AKA SMJ-40
            Modula PWB
            Calliope CC Supreme
            Natalie P Ultra
            Natalie P Supreme
            Janus BP1 Sub


            Resistance is not futile, it is Volts divided by Amperes...
            Just ask Mr. Ohm....

            Comment

            • ThomasW
              Moderator Emeritus
              • Aug 2000
              • 10934

              #7
              Found an interesting post from Mark Seaton

              This is one audiophile myth which still needs to be dispelled. Mass has absolutely ZERO effect on the "speed" of a woofer. A loudspeaker is an acceleration device, not velocity. So, much like gravity, the mass will not affect the rate of change. In reality, you NEED a heavy woofer to make deep bass. If you want deep bass in a small box without huge EQ, you need an even heavier woofer. In terms of low frequency re-production it is largely related to mass per cone area. As such, it is actually easier to build a 12" to produce deep bass than it is an 18. As a rediculously extreme example, I have a woofer system here which is about the same size as a Velodyne 18 with TWO 18" cones, no-EQ needed, and the total moving mass is just shy of 10 POUNDS between them. Heavy woofers are cool 8-).

              Mark Seaton
              Sound Physics Labs / ServoDrive
              For those that don't know Mark, Tom Danley or what Sound Physics Labs is about look HERE They make some amazing LF devices.




              theAudioWorx
              Klone-Audio

              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

              • Hank
                Super Senior Member
                • Jul 2002
                • 1345

                #8
                What say you all?
                Okay, I'll bite, professor. Mark says mass has nothing to do with driver speed, and he also says that a speaker is an acceleration device. Following that, I should be able to go out to the parking lot and from a standing start, on a level surface, I should be able to push (accelerate) a car as fast as I can push (accelerate) a bicycle.
                I don't think so. That tells me that the weight (mass) of a cone/surround should make a difference in driver speed. Can anyone reading this post hear a difference in "speed" between drivers of different moving mass weights? If not, then I'm guessing that the differences between driver moving mass weights is too small to make an audible difference.

                Does that open up enough questions?

                Teach us, Grand Poobah's.

                Comment

                • Davey
                  Senior Member
                  • Jan 2003
                  • 355

                  #9
                  I think what Mark is saying is that (increased) mass is not a factor assuming you have the motor to drive it.

                  F=ma

                  Double the mass, double the force and you can maintain the same acceleration.

                  Davey.

                  Comment

                  • Andrew Pratt
                    Moderator Emeritus
                    • Aug 2000
                    • 16507

                    #10
                    Following that, I should be able to go out to the parking lot and from a standing start, on a level surface, I should be able to push (accelerate) a car as fast as I can push (accelerate) a bicycle.
                    On that same thought though which would win in a drag race a ford focus or a corvette? The vette likely weighs double the focus but it wouldn't be a contest for which is faster...if you have the motor strenght weight can be overcome...of course the light the weight the easier it is to move but its a case of the whole system needing to be evaluated not just one parameter.




                    Comment

                    • Hank
                      Super Senior Member
                      • Jul 2002
                      • 1345

                      #11
                      ...its a case of the whole system needing to be evaluated not just one parameter.
                      That's it - motor strength related to the mass it drives. What else can we bring out to end once-and-for-all, the driver "speed" debate? Hey, Thomas threw out the bait - I thought I'd help get a feeding frenzy going. I know what the problem is - this is too kind of a forum. Let's move this to ... :twisted:

                      Comment

                      • Andrew Pratt
                        Moderator Emeritus
                        • Aug 2000
                        • 16507

                        #12
                        I know what the problem is - this is too kind of a forum
                        Ok Hank you're an idiot...there feel better :LOL:

                        just kididng by the way...please forgive me....I'm groveling now....awe who are we kidding yes we're a friendly forum




                        Comment

                        • Hank
                          Super Senior Member
                          • Jul 2002
                          • 1345

                          #13
                          Andrew, whew! Now I feel better! I hate fishing for compliments, but I wanted one really bad, so...

                          C'mon, Thomas, get this thread rerailed back to:
                          Which drivers for IB and Dipole configs.

                          Comment

                          • JonMarsh
                            Mad Max Moderator
                            • Aug 2000
                            • 15209

                            #14
                            The correct answer is,

                            Which ever one you want




                            because this is the

                            D. I. Y.

                            forum, which is Do It Yourself..... so you choose.


                            Otherwise, it's just an engineering problem and a systems integration issue, and we can make this like a big programming DO loop and return the flow to my previous silly post above....


                            What will work? DPL 12's, SHIVA's, TEMPEST's, Titanic II's, HE-15's, all will if the integration issues are properly addressed. Some offer better boom for the buck (subs don't "bang" now, do they, unless they're driven beyond the mechanical limits of excursion, so lets have no banging subs.....) :B

                            It's YOUR choice.....


                            -Jon


                            PS. And I haven't even had my latte this morning, and only had about 3 hours of sleep last night (due to back).. can you spell "Cranky"?




                            Earth First!
                            _______________________________
                            We'll screw up the other planets later....
                            the AudioWorx
                            Natalie P
                            M8ta
                            Modula Neo DCC
                            Modula MT XE
                            Modula Xtreme
                            Isiris
                            Wavecor Ardent

                            SMJ
                            Minerva Monitor
                            Calliope
                            Ardent D

                            In Development...
                            Isiris Mk II updates- in final test stage!
                            Obi-Wan
                            Saint-Saëns Symphonique/AKA SMJ-40
                            Modula PWB
                            Calliope CC Supreme
                            Natalie P Ultra
                            Natalie P Supreme
                            Janus BP1 Sub


                            Resistance is not futile, it is Volts divided by Amperes...
                            Just ask Mr. Ohm....

                            Comment

                            • Hank
                              Super Senior Member
                              • Jul 2002
                              • 1345

                              #15
                              "It's your choice"???

                              Jon, you're the one who posted the topic. You are in a silly mood. 5,000 comedians out of work and engineer Jon is trying to be funny. Tisk, tisk, tisk. What in the Wide, Wide World of Sports got into you? I was going to guess you'd been into the vanilla extract again, but then noticed your reference to 3 hours sleep, which does make some people a bit punchdrunk.

                              Alright, one more try, futile as it may be: Grand Poobah Jon, lead us back on track (topic).

                              Comment

                              • Jack Gilvey
                                Senior Member
                                • Aug 2001
                                • 510

                                #16
                                Here's another great article from John K., this time on dipole "bass Cannons":

                                http://www.geocities.com/kreskovs/basscannon.html

                                Gotta give it a whirl, of course.

                                Comment

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