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  • 2 way speaker with very little crossover components...

    Hi guys, I'm trying just for fun to see if I can try and put together something which may give reasonably good sound with virtually no crossover components. Long ago Ihad a chance to hear a speaker by a company called Reference 3A and I was blown away. I then found out it had only a single cap on the tweeter at 3K and nothing else.

    http://www.reference3a.com/mmdecapo.htm

    So how hard is it to find a woofer with a smooth response where it can roll off gently without terrible breakup and a tweeter that works safely with just a cap. I'd obviously have to cross it over a bit high - or I'd assume.

  • #2
    Re: 2 way speaker with very little crossover components...

    Originally posted by contoursvt View Post
    Hi guys, I'm trying just for fun to see if I can try and put together something which may give reasonably good sound with virtually no crossover components. Long ago Ihad a chance to hear a speaker by a company called Reference 3A and I was blown away. I then found out it had only a single cap on the tweeter at 3K and nothing else.

    http://www.reference3a.com/mmdecapo.htm

    So how hard is it to find a woofer with a smooth response where it can roll off gently without terrible breakup and a tweeter that works safely with just a cap. I'd obviously have to cross it over a bit high - or I'd assume.
    My "Nano Neos" used an $8 tweeter along with a woofer that's now on sale for $15, along with a $7 crossover. It's only got 6 parts. Most tweeters will at a minimum need to be attenuated (with a series resistor) to get their output to match a woofer's, and a cap to protect the tweeter, but an L-pad works better (sometimes) than just a series resistor as it tends to smooth out a tweeter's impedance variations, and most of the time, you're trying to cross the tweeter only an octave above it's resonant frequency, which is more safely done with a 2nd order filter (series cap AND shunt coil), although I just went 1st order on my Nano Neos.

    It all depends on your expectations, I guess.

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    • #3
      Re: 2 way speaker with very little crossover components...

      Originally posted by contoursvt View Post
      ...So how hard is it to find a woofer with a smooth response where it can roll off gently without terrible breakup and a tweeter that works safely with just a cap. I'd obviously have to cross it over a bit high - or I'd assume.
      Both devices would have to have sufficient overlap in the crossover range to allow the use of the simple 6db crossover to integrate.
      A conundrum is that the larger the driver the lower the frequency at which it becomes directional, that forces a lower crossover...
      so the simple 6db 2way with large drivers doesn't integrate as well as small drivers to tweeters with 6db crossovers.
      "Not a Speaker Designer - Not even on the Internet"
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      • #4
        Re: 2 way speaker with very little crossover components...

        I guess you'd have to make your way through a pile of drivers with a wt3 and FR rig to find 2 that match up very well.

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        • #5
          Re: 2 way speaker with very little crossover components...

          You could go with something like this Tang Band 264-850 running full range and a tweeter as Chris described. A popular tweeter is this one 275-030. It would need minimum attenuation. You can find an L-pad calculator here L-Pad Calculator.
          Have fun,
          Mike
          "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

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          • #6
            Re: 2 way speaker with very little crossover components...

            I see one issue with running any woofer full-range, and that is compensating for the baffle step. If this is a compromise one is willing to make, than by all means go for it.

            FWIW, right now I have a "retro" project in the works which uses some old Radio Shack drivers. There is one possible variation which uses a classic "cap and coil" crossover plus a series resistor to tame the tweeter down. I am not 100% sure the ragged on-axis response is worth whatever perceived benefits are gained by using fewer components. I have modeled hundreds of driver combinations, and have come across very few that would work acceptably with such a minimalist crossover.

            The Peerless SDS 5-1/4" woofer would work with a simple crossover.
            Don't listen to me - I have not sold any $150,000 speakers.

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            • #7
              Re: 2 way speaker with very little crossover components...

              Originally posted by Sydney View Post
              Both devices would have to have sufficient overlap in the crossover range to allow the use of the simple 6db crossover to integrate.
              A conundrum is that the larger the driver the lower the frequency at which it becomes directional, that forces a lower crossover...
              so the simple 6db 2way with large drivers doesn't integrate as well as small drivers to tweeters with 6db crossovers.
              Not necessarily.

              If the woofer has a natural 2nd order roll off at 3KHz for example, and the tweeter's natural response matched it with a single cap, you'd have an LR2 response. When you see the angled baffle, kind of makes me think that's what they did.
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              • #8
                Re: 2 way speaker with very little crossover components...

                Originally posted by johnnyrichards View Post
                I see one issue with running any woofer full-range, and that is compensating for the baffle step. If this is a compromise one is willing to make, than by all means go for it.
                Hey Johnny,
                So, is there a baffle step compensation calculator available? How do you figure how much baffle step to compensate for? If the baffle is wider, is there less compensation needed?
                Thanks,
                Mike
                "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

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                • #9
                  Re: 2 way speaker with very little crossover components...

                  It would be very hard to make a good sounding 2-way speaker with the only crossover component being a cap on the tweeter. At my parents house they have a set of speakers in the garage made like this, a lot of cheap boom box speakers are. In most cases it's pretty rubbish. Technically, it could be done successfully if you have find the perfect marriage of woofer and tweeter. Say the woofer has a natural roll off and you take advantage of that..... To make a good sounding speaker this way would really just take a lot of R&D testing components, measuring, trial and error.

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                  • #10
                    Re: 2 way speaker with very little crossover components...

                    Originally posted by mikejennens View Post
                    Hey Johnny,
                    So, is there a baffle step compensation calculator available? How do you figure how much baffle step to compensate for? If the baffle is wider, is there less compensation needed?
                    Thanks,
                    Mike
                    The amount is determined (more or less) by the distance from boundaries. The frequency is determined by baffle width.

                    There is a "textbook" calculator floating around somewhere, if my PC mobo had not died last week I could zip it up to you ASAP, but right now I do not have access to it.

                    EDIT: it is here.

                    IF you are out there, HongRN, we miss you and thank you!
                    Don't listen to me - I have not sold any $150,000 speakers.

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                    • #11
                      Re: 2 way speaker with very little crossover components...

                      Of all the "it's just got a single cap on the tweeter" designs, this one seems to have its ducks in a row.

                      First, the baffle is slanted to align the acoustic centers.
                      Second, the tweeter appears to be the Seas 27TDFC... or something related. That is one of the only tweeters I've ever used that can do a 2LR acoustic rolloff with just a cap and an L-pad.
                      I don't know what woofer that is, but chances are it has a very flat frequency response.

                      As times have shown, it is cetainly possible to make a listenable speaker with just a cap on the tweeter and the woofer's natural roll-off. But I think it takes a lot of experimentation with finding the right cabinet shape, bass alignment, and most importantly the driver choices. The chances of just slapping two drivers together with this filter topology and expecting it to sound good is a shot in the dark at best.
                      Isn't it about time we started answering rhetorical questions?

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                      • #12
                        Re: 2 way speaker with very little crossover components...

                        Thanks for everyone's input on this. So pretty much I should forget about trying something like this because it aint easy. Well the woofer is something thats made in house or at least thats what I read.

                        All I can tell you guys is that after hearing the speaker in person, I can say its quite exceptional. Very nimble and just vanishes in the room. I would love to have a pair one day but the price is quite high.

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                        • #13
                          Re: 2 way speaker with very little crossover components...

                          Note that a speaker itself is a complex device with a reactive nature. Changing its behavior with crossover components is no different than simply 'modifying the driver' - within limits, of course. Crossovers should not be feared ...
                          I am trolling you.

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                          • #14
                            Re: 2 way speaker with very little crossover components...

                            Originally posted by contoursvt View Post
                            Hi guys, I'm trying just for fun to see if I can try and put together something which may give reasonably good sound with virtually no crossover components. Long ago Ihad a chance to hear a speaker by a company called Reference 3A and I was blown away. I then found out it had only a single cap on the tweeter at 3K and nothing else.

                            http://www.reference3a.com/mmdecapo.htm

                            So how hard is it to find a woofer with a smooth response where it can roll off gently without terrible breakup and a tweeter that works safely with just a cap. I'd obviously have to cross it over a bit high - or I'd assume.
                            I bought some Altec Lansing 8" coax speakers in the early 80's that only had one cap no the tweeter and they sounded great, even without a baffle step. They were rated 50 to 17khz. I wish I had some of them now.They were meant to be put in a wall or ceiling but sounded fantastic in my car.

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                            • #15
                              Re: 2 way speaker with very little crossover components...

                              Originally posted by contoursvt View Post
                              Thanks for everyone's input on this. So pretty much I should forget about trying something like this because it aint easy. Well the woofer is something thats made in house or at least thats what I read.

                              All I can tell you guys is that after hearing the speaker in person, I can say its quite exceptional. Very nimble and just vanishes in the room. I would love to have a pair one day but the price is quite high.
                              If you hang out around here enough and ask questions, you'll be able to get some affordable speakers with which you'll be more than satisfied. And... if you can make it to the DIY shows, things get even better. I'm working on designing my first set of speakers, and asking a lot of questions.
                              Have fun with it.
                              Mike
                              "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

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