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Matrix - Reloaded.

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  • Matrix - Reloaded.

    Early in the Movie "The Matrix" Neo is given a choice of the red pill or the blue pill. As such I have a simpler design using the Dayton RS150 and BG Neo3PDR, which has been around since about 2006 and a more involved design using the Neo3PDR, Neo8, and dual RS150T's that was developed in 2009.

    The red pill will allow one to see just how far the rabbit hole goes, so that title must be given to the TMWW version that uses a BG Neo3PDR tweeter, BG Neo8 (non-PDR) midrange, and dual Dayton RS150T woofers.

    The Matrix is so named because the BG Planar drivers with their orderly series of openings and rectangular shape always reminded me of a matrix. Also, I've always been impressed with the way planar drivers deal with dense complex passages. When I think of the movie "The Matrix" the scene that stands out is when Neo and Trinity enter the office building armed with just about every automatic weapon imaginable and proceed to shoot everything in sight - just the kind of scene these drivers where made to reproduce.

    This design is a tall slender floor stander - 43.5" tall by only 7" wide and 14.5" deep. The form factor, coupled with the matte black finish is intended to blend well on either side of a big flat panel TV. The cabinet size and driver positioning allows the Neo8 to be mounted at a height to align with a typical seated position, which is important given its limited vertical dispersion.

    Before designing these, I did some homework. A couple of Neo3/Neo8 designs had been attempted. Javier Huerta had documented a design called the Minilith on the HTGuide forum that used an 8" Seas woofer and LouC had attempted an open baffle mid tweeter design with an RS-225 woofer. I was relatively impressed with how Javier's design came out, but had a completely different form factor in mind and had a pair of RS-150T's in hand that I won as a door prize courtesy of PE at DIY Iowa 2008.

    Based on some of Javier's findings, I decided to keep the range of operation of the Neo8 relatively limited at 1 to 3.5 kHz, but to use shallow slopes to mitigate any issues with differing off axis behavior between the drivers. I also decided to pair up the RS-150T's to give a little more power handling and air-moving capability to support the extension in the 30's they can provide in a larger enclosure.

    I ran a few sims and completed cabinet construction with the help of my brother just in time for DIY Iowa 2009. I received a lot of favorable feedback, particularly regarding the midrange performance of the Neo8. A couple of people thought the Neo3PDR was voiced a little hot, but the greatest criticism had to do with the RS150T's trying to make deep bass in the Grinnell auditorium.

    After the show, I brought the crossovers back out of the cabinets and made some changes and also worked on the cabinet alignment. For the cabinets, I decided to extend the port length (3" diameter PVC) from 4" to 6.5" to create an extended bass shelf alignment. I also added heavy polyfill to the bottom quarter of the cabinet to make sure that any pipe resonances due to the tall, slender enclosure were fully dealt with. These changes greatly improved bass quality and control.

    For the crossover, my sims did not accurately represent the effect of the rear chamber, which was formed by a rectangular clearance hole for the Neo 8 extended through two layers of 3/4" mdf and lightly stuffed with polyfill. The impact, as I found out when I finally measured these, was a slight response peak around 800 Hz, a downward slope through the midrange with a dip of about 2-3 dB centered around the mid-tweeter crossover point of 3.5 kHz.

    The final crossover achieves a very flat, balanced on-axis response through the midrange and treble up to about 16 kHz with a sharp dropoff above that. The reason for that is a small series inductor in series with the Neo3PDR. The series inductor reshapes the Neo3PDR's response to help alleviate the lack of energy between the two peaks at 3.5 kHz and 12 kHz. I think the approach worked very well in making the Neo3PDR sound better balanced throughout its range.

    Overall, I am very happy with how this project has turned out. The BG drivers have increased a lot in price since I started, but these offer some of the best resolution without harshness that I've heard from the midbass region through the treble. The bass is articulate and is quite satisfying in most small to medium rooms. In a large room or HT, one would likely want to supplement these with a sub. The attachments should give a good starting point to anyone who might want to give these a try.
    Attached Files
    Last edited by scottsehlin; 05-22-2012, 06:22 PM. Reason: Figures added
    Keep an open mind, but don't let your brain fall out.

    Argon | Helium | Lithium | LithMTM | Hafnium
    Mercury | Matrix | Shrubbery

  • #2
    Re: Matrix - Reloaded.

    I've finally made some progress with the blue pills, converting an old pair of AR4x speakers. I'm posting a picture of the baffles, which are nearly done, and I'll give details if anyone wishes. Again, I appreciate Scott's generosity in sharing his designs and offering help along the way. I'll post again when I have more progress to show.
    Attached Files

    Comment


    • #3
      Re: Matrix - Reloaded.

      After a surprisingly long time I nearly have the Blue Pills done. Very, very nice speakers, especially the mids and highs. I made baffles and attached them to enclosures from old Acoustic Research AR4x speakers. I still have to fill the counterbore holes and brace the boxes. Also, as Scott had mentioned to me, they play pretty low but not loud, so I'm considering sub options. Pictures attached, although the speakers came out much better than the pics. Just for fun I include pictures of the speakers on their stands--the one with the white grill cover is an Acoustic Research AR2AX and the one with the drivers visible an Infinity Qb. Thank you very much Scott for the design and the help. I really appreciate your sharing your expertise; I'm hearing alot more music now!
      Attached Files

      Comment


      • #4
        Re: Matrix - Reloaded.

        I'm glad to hear you're enjoying the "blue pills". I too am a former EMIT tweeter owner, and can attest that the Neo3 is a nice upgrade if you appreciate the virtues of planars.
        Keep an open mind, but don't let your brain fall out.

        Argon | Helium | Lithium | LithMTM | Hafnium
        Mercury | Matrix | Shrubbery

        Comment


        • #5
          Re: Matrix - Reloaded.

          I just want to let you know how pleased I am from using the top 2/3 of your Matrix design in my DIY speakers. MY project uses a top cabinet containing BG Neo8PDR and BG Neo3 PDR and a separate cabinet housing Kilpsch 6.5" buyout for each channel. The mid and high range crossovers are the same as used in Matrix. I always like the sound of electrostatic speakers and IMO, the clarity and tonality of the mid and high of this 2/3 Matrix design are very electrostatic-like. Thanks for publishing your design!

          Comment


          • #6
            Re: Matrix - Reloaded.

            Thanks for the kind words. I am glad someone is getting use out of this design.
            Keep an open mind, but don't let your brain fall out.

            Argon | Helium | Lithium | LithMTM | Hafnium
            Mercury | Matrix | Shrubbery

            Comment


            • #7
              Re: Matrix - Reloaded.

              Originally posted by scottsehlin View Post
              Thanks for the kind words. I am glad someone is getting use out of this design.
              For now I prefer the Neo8 PDR in open back fashion. THe lack of anything irritating in the mid and high as well as the huge imaging(beyond the speaker boundary) make them extremely enjoyable. My poor Klipsch 6.5" buyout woofer is probably outclassed by these BG drivers but at least is not mucking up the sound:D By going two-cabinet modular design I can upgrade the bass module easily if needed.

              Comment


              • #8
                Re: Matrix - Reloaded.

                Just to post a picture of the crossover.
                Both coils are 12 AWG air cored. All capacitors are films type(TRW, Relcap and Madisound buyout), resistors are MOX type.
                Attached Files

                Comment


                • #9
                  Re: Matrix - Reloaded.

                  I keep meaning to post here, that I really enjoyed the iteration of these at Indy. I would have liked to hear them in a smaller room, as the bass kind of got lost in the conference room.
                  Don't listen to me - I have not sold any $150,000 speakers.

                  Comment


                  • #10
                    Re: Matrix - Reloaded.

                    That is the main issue with the RS150's. The bass does fill in reasonably well at home.
                    Keep an open mind, but don't let your brain fall out.

                    Argon | Helium | Lithium | LithMTM | Hafnium
                    Mercury | Matrix | Shrubbery

                    Comment


                    • #11
                      Re: Matrix - Reloaded.

                      I am interested in using the top half of this design as well. However, I would like the crossover between the woofer and the Neo8 to be active.

                      I am not that familiar with passive x-over design. Any idea what would be removed from the Neo8 crossover to allow it to be 'full range' up to the 3.5K crossover to the Neo3?

                      Comment


                      • #12
                        Re: Matrix - Reloaded.

                        Originally posted by rhubarb9999 View Post
                        I am interested in using the top half of this design as well. However, I would like the crossover between the woofer and the Neo8 to be active.

                        I am not that familiar with passive x-over design. Any idea what would be removed from the Neo8 crossover to allow it to be 'full range' up to the 3.5K crossover to the Neo3?
                        In theory, the only component that needs to be removed is the 10 uF capacitor that is between the 1 ohm resistor and the 0.47 mH inductor in the schematic. I looked at a simulation of that, and in reality going from a 3 way crossover to a two way with the Neo8 and Neo3PDR, I would recommend changing the values of the remaining 3 components. A 0.27 mH inductor, 1.5 ohm resistor, and 15 uF capacitor should give a response very close to the original 3-way.
                        Keep an open mind, but don't let your brain fall out.

                        Argon | Helium | Lithium | LithMTM | Hafnium
                        Mercury | Matrix | Shrubbery

                        Comment


                        • #13
                          Re: Matrix - Reloaded.

                          Thanks very much for re-modeling it.

                          One question .. I have the Neo8PDR version of the driver which is 1.5dB less sensitive that the non PDR version. Should the Neo3PDR be attenuated to match?

                          Comment


                          • #14
                            Re: Matrix - Reloaded.

                            That 1.5 dB will require reducing the value of the 1.5 ohm resistor. I would guess you will wind up somewhere between 0 and 1 ohms. I could try to sim a little further by dropping the Neo8 level by 1.5 dB and leaving everything else the same to see if there would be any impact on the other components.
                            Keep an open mind, but don't let your brain fall out.

                            Argon | Helium | Lithium | LithMTM | Hafnium
                            Mercury | Matrix | Shrubbery

                            Comment


                            • #15
                              Re: Matrix - Reloaded.

                              If the only difference between the Neo8 and Neo8PDR is a 1.5 dB across the board drop in sensitivity, then I would shoot for 0.2 mH inductor, 1 ohm resistor and 18 uF capacitor for a Neo8PDR low pass filter.
                              Keep an open mind, but don't let your brain fall out.

                              Argon | Helium | Lithium | LithMTM | Hafnium
                              Mercury | Matrix | Shrubbery

                              Comment

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