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Four Subs off Two Amps, and Modified Rally Sports

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  • Four Subs off Two Amps, and Modified Rally Sports

    I'm still working on a deign for my HT and wanted to bounce some ideas of y'all. I like the Rally Sports.

    Back to that in minute.

    I also like the idea of four subs one in each corner of the room to smooth out the response across the room (rear set with reversed polarity). PE has some factory buy out 1000 watt sub amps and I'm thinking of using one amp to drive two subs x 2.

    Since I plan to use multiple subs i don't think I need the 15" Pro subwoofers used in the Rally Sports. I know I need extension one octave or more below the Home Theater Reciever's (Onkyo TX-N585) chosen cross over point for the subs (80hz?), but I'm hoping that I can find a woofer of ~93 db/watt to match the mid's at thier 500 Hz cross over point.

    Any ideas, thoughts, or notions I'm wandering lost in the woods?

  • #2
    I went to the woofer selection guide and found what might make more sense than a smaller woofer in the Rally Sports. An MTM using two PA200-8 and the selenium DT220Ti Cross over at 2,000 Hz 12 db/oct. PE says 42 Hz F3 in a 1.1 cubic foot box. So 2.2 cubic feet overall. If i remember things correctly the efficiency goes by 3 db with two 8 ohm speakers in parallel. Is that right?

    Seems like I have seen something similar here somewhere.


    • #3
      I might be wrong, but Javad's Rally Sport was designed more for events. That is, they were designed for DJ / PA capabilities rather than home Hi-Fi. That said, you may want to focus on home speaker designs suited to HT with separate subs. Anything you build yourself can always be finished in the Rally Sport "look".


      • #4
        I may be completely off cours, but the idea was to get efficient, fast, clear, and loud.

        I must admit to being a bit frustrated though. 30 years ago I pretty much had the whole audio component market memorized. I could look at most commercial speakers and tell you what components were in them by model number. For example a DCM time window had two ADO163T-8s and AD7066W8 each. There is just so much more available these days and I have lost touch with those key pieces that represent points of diminishing returns. And using horns? I would have never built a speaker with horns back then, but I'm taking a chance on this newest breed.

        After playing with Dynaudio and electrostatics I don't expect audiophile perfection from these. Just the ability to simulate a commercial theater in a 400 square foot room. A "voice of the home theater" speaker.


        • #5
          There's an easier path to your goal than kit bashing someone's design. There are lots of 2 and 3 way horn tweeter designs using PA style woofers of various sizes. Home Theater biased. Efficient, loud, requiring subwoofers for full range results. Search diysg, trusted source. Better known at AVSforum diy speaker subforum.

          JMHO. Build whatever you wish.


          • #6
            Please explain "kit bashing." I thanked the Rally Sport designer for sharing his design on his own thread and refernce them here because they are close to what I need and a good starting point. Did I do something wrong?

            I'm aware of the DIYSG kits, but I'm trying to do something myself that fits my needs and spend less money doing it. Isn't that the whole point of DIY audio. Determine what your goals are and then build exactly what you need for less money than buying it off the shelf.

            I admired the Rally Sports because of the similar design goals and how the designer went about achieving them. As I siad before, a good starting place for me.

            However, as I add subwoofers (because I have a room with four walls for my home theater and don't have the need to cart speakers to gigs) and shrink the woofer, the need for the seperate midrange goes away. And by doubling the the new smaller woofer I get a 6 db increase in efficiency (not 3 as I stated above) due +3 db mechnical and +3db electrical. This brings the midbass and midrange up to somewhere around the efficiency of the horn tweeter.

            So started with similar goals, but with different environments we gat to similar results using a different design.

            I was looking for input and discussion. Sorry if my post left room for the impression of anything but admiration for the Rally Sports and designer.


            • #7
              Ummmm yeah, I didn’t read anything as bashing at all. I think the Rally Sport would make a fine home theater speaker. Kinda like Klipsch in a way. I used to have their reference line and I absolutely loved them for home theater, the best. They couldn’t hold a candle to my Magnepans or Kef 105s when it came to music reproduction though.

              Right now I’m building my three fronts, a tower using a 12” coaxial and a 12” woofer to cover more of the lower midbass. They’re both pro drivers, accordion surrounds, 4” voicecoils, etc. They’re being crossed to a pair of 18” ultimax subs. I would never dream of replacing them with a conventional speaker.



              • #8
                OP, I responded to your visitor message post.

                The gist is the term "kit bashing". It is a method in model building and craft hobbies of combining parts of available kits or designs with other kits or designs or one's own intellectual property to produce a unique result. I did not suggest you were criticizing Javad's work.

                Sorry for the misunderstanding.

                Kitbashing - Wikipedia
                Last edited by djg; 05-19-2019, 02:19 PM.


                • #9

                  Thanks for the reassurance. I have a pair of electrostatics sitting in the room with me now. NOT a good choice for home theater. As I said, pro drivers and horns are outside my comfort zone, but seem to be what is needed for this application. I doubt I can go too wrong with the subwoofers, and the Selenium CD seems a sure bet, so bridging the gap is the only challenge. I'll talk to the PE Tech rep tomorrow, but for now I just need to find some good free cross over design software.


                  • #10
                    Can't seem to find FRD and ZMA files for the Selenium D220Ti with a wave guide.


                    • #12
                      Thanks djg. Found them there.


                      • #13