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  • Crossover Help

    Hi everyone, i have just joined the community.

    So i am approaching DIY speaker and i have decided to go 4ohm 1 TW and 2 Woofers as follow, before asking why i have ARC VM220 with 200wpc. with selectable 4ohm output.

    D2904/710003 - Tweeter 25mm Scan Speak - Revelator - 4ohm:
    21WE/4542T-00, Scanspeak Ellipticor 8" Mid-Woofer, 4 ohm
    22W/4851T00 - 8" Woofer Scan Speak - Revelator - 4ohm


    First i thought to go with 3-way crossover than i've read about 2.5 way which as far as i understand is not possible as the two 8" drivers are not the same correct?

    I also tought to use a 2-way crossover, wire in series 2 woofer to get 8ohm, and low pass band for the 22W/4851T00 but i'm not sure on how to wire the thing

    So will this crossover work? If yes any suggestion for wiring?
    https://www.parts-express.com/prv-au...tion--294-2869

    If above is possible can you explain how to wire?

    Thanks in advance for your advice

    Best


  • #2
    Hello and welcome!

    A couple thoughts:

    1) Those are some very nice drivers and they deserve a proper crossover designed for them in the cabinet they will be in, not a premade crossover. Off the shelf crossovers like that will give you less than optimal results and you may as well use much less expensive drivers if going that route.

    2) Rather than using an 8” mid bass and 8” woofer, I would use a smaller mid in a proper 3-way format. If you want to stick ellipticor I’d look at the 18w or smaller if they make it. Otherwise I’d consider a 15m revelator.

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    • #3
      If you provide the dimensions of your baffle, someone here (paging Dr Roemer) can whip up a crossover schematic for you that is much better than a premade one. Working with factory specs and graphs is still limiting though, where real measurements of your drivers in your baffle would be better.

      Id recommend asking someone here to design a crossover for you, then while enjoying that, learn to measure and design your own, and have fun with learning the skills too!

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      • #4
        Tell us your box design specifics (HxWxD, closed/vented - and if so, the tuning freq.)?
        dynamo makes some good points. (I'd assume you're running the WE as a mid -only?) Mixing different woofers for bass is a no-no.
        A great book (for research) is "SpeakerBuilding 201" by Ray Alden.

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        • #5
          Nobody has explained to him why the off the shelf crossover is a bad idea. I'll take a stab at it, but I'm just learning myself.

          Standard crossovers like this don't take a lot of things into account. The biggest one I'm aware of is that the impedance of each driver varies with the frequency it is reproducing, and that will in turn affect its sound pressure level. The off-the-shelf filter behaves as though the impedance is constant, like a resistor, which it isn't . Also, the off the shelf cannot take into account the geometry of the mounting on the baffle, cannot apply baffle step correction, etc.


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          • #6
            skatz is right. These drivers deserve a specific crossover to match their impedance curves and frequency responses. If you buy a premade crossover, at best it will sound mediocre, at worst the crossover might cause a low impedance situation and you end up with a blown amplifier.

            Assuming you do not want to invest in a measurement setup (quite cheap in the overall cost of building an expensive pair of speakers). There's a thread calling "designing speakers without measurements" on another forum. I think there is also a how to guide here. You can get quite good results using manufacturer curves then overlaying your own baffle response and enclosure frequency extension. The downside is you will need to spend months reading, asking questions and coming up to speed.

            In my opinion - these months are well spent. Otherwise you will waste money and more time throwing a "random selection of crossover parts" to your speaker and wonder why it sounds like crap.

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