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The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

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  • The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

    Objective.

    To build a slim, small, high-WAF speaker not easily affected by room acoustics.

    I've wanted to build an open baffle / dipole speaker for quite some time, but size considerations and driver price kept me away from them. Due to solutions like the MiniDSP, and efforts like John K's NaO speakers, I decided to build a hybrid speaker in every way.

    It's not fully active - the x-over between the woofers and the mid / tweeter panel is active, but the mid / tweeter X-O is passive. The active x-over does some response shaping and time alignment too - plus I'll eventually use it to add basic loudness contours (since my equipment does not have tone controls). (The MiniDSP is simply incredible).

    And it's not fully dipolar - from 120 Hz and up, the mid / tweeter panel crosses over with 4th order L-R slopes; below that, from 30 Hz to 120 Hz, a bandpass filter allows the bass enclosure to deliver solid bass without overloading the little woofers.

    It's fully fun, though. And a revelation to listen to, coming from boxed speakers.

    The name.

    The original name was Valkyries. I don't know why. For a while, they were going to be the Elyseums. Neither name stuck. Then I listened to them and one word came to mind: "truth". Unfortunately, Veritas, and Verita are already taken.

    So I looked at the glossy finish, and the way the drivers interact with their surroundings, and one name came to mind: Reflections.

    "Reflexos" is portuguese for that word. Why portuguese? Because that's the language the word looked the nicest.

    The hardware.

    Living abroad, buying big drivers is sometimes out of the question. The last time I tried I spent close to $500 for 4 RS270s. I'm not doing that again anytime soon.

    Besides, I wanted a slim design. True, I could use the woofers in a side-firing configuration, but this being my first OB, I didn't want to add too much complexity to an already unknown design. Plus, once I decided on a Vented Box bass alignment, I could use smaller drivers.

    The RS-150 drivers fit the bill. I could use 4 of them - 2 on the mid panel, 2 on the vented box. They are small. They can be used in slim speakers. They sound great - I've already tried them and liked them. They can go up to 1.8 KHz or so using a 4th order filter. And I already had 8 of them.

    Allright, so the whole design was born because I had 8 RS-150s.

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    (Yep. I used the old ones, with the bucking magnet).

    The tweeter was a bit more complex. At first I wanted to use the Seas DXT tweeter - then I decided I wanted a full dipole from 180 Hz or so on up, so I'd need two DXT's - expensive. I figured I had a pair of Neo3 PDRs from a box speaker I wasn't using anymore, so I decided to take them out of their enclosures and use them on my new design, with a round flushmount faceplate.

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    (I sanded them, removed the B&G logo and painted them gloss black. No free advertisements here!).

    The MiniDSP was sort of a given - I already had it because I used it to integrate a set of small bookshelfs with a 15" woofer succesfully. And I needed it to shape the response, in order to counteract the dipole bass loss and whatever FR abherrations I could find, and the baffle step for the vented woofers.

    Click image for larger version

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    (Yeah, it's the balanced one. No way I'm using the non-balanced unit - with a 1V output, I'd be wasting a lot of amplifier power).

    For amplification, I wanted to go fancy and use a McIntosh MC-250 for the bass units, and two McIntosh MC-30 amps for the dipole panel. Realistically, though - tube amps are a coin toss when it comes to mating with a particular set of speakers. So I took out my Rotel RB-1070 pair of amps.

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    Last edited by fjhuerta; 01-06-2013, 08:23 PM.
    Line Array: IDS-25 Clone, FE-83.
    2-2.5 Way:
    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

  • #2
    Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

    Preliminary tests.
    You can read all about them here.

    Suffice to say, cutting the baffles to size makes all the difference in the world. HINT: Do read and understand John K's ABCDipole .zip package - follow the instructions and you'll end up with an extremely nice speaker!

    Design.
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    Google SketchUp was my friend. I'm not building any other speaker without modeling it there first. I placed the speaker in different rooms, and got an excellent idea on how the speakers would look at home.

    The dipole panel is a simple L-shaped piece, with a reinforcing piece on the back. The vented box is about 33L in size. If you need accurate dimensions, you can open the SketchUp file I attached to this post.

    EDIT: The forum didn't let me attach a .zip, .rar or .skb file, so if you need them, just send me a PM and I'll get you the files.
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    Line Array: IDS-25 Clone, FE-83.
    2-2.5 Way:
    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

    Comment


    • #3
      Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

      Dipole panel modeling.

      I used The Edge to model the baffle. At first I tried to minimise the baffle effect. Realistically, though, it didn't matter. As long as I followed ABCDipole's instructions on not going above around 22 cms. width, response was pretty good.

      Construction.Click image for larger version

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      Line Array: IDS-25 Clone, FE-83.
      2-2.5 Way:
      Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
      3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

      Comment


      • #4
        Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

        Crossovers

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        I didn't use any stock files with added diffraction / dipole modeling. Every measurement I did I took from my own baffle, JustMLS and my calibrated Dayton ECM-8000.

        My target curves were 4th order L-R all around. In order to reach them, I used a 4th order electrical on the tweeter, and a 2nd order electrical with a tank on the woofer, to kill any hint of a break-up in them. Simple... very simple.

        BONUS: check out the crossover. See anything unusual? Well, no. Everything is pretty normal - except for a simple thing. There isn't a single resistor there. The minimal matching I needed to do between woofers and tweeter I accomplished by using the DCR of the inductors. Some of them are 14 GA, others 15, 18 and 20GA. The tweeters and woofers simply came together perfectly. I was impressed at the way I picked the exact drivers I needed to accomplish this (actually, I'll be brutally honest - it was sheer luck, and I was actually very worried the tweeters would not reach the woofers' output at 1W).

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        Here are the RS150's with the Neo3. Look at that dipole response. It needs some TLC. But that isn't going to happen on the passive crossover - this will help in keeping efficiency as high as possible. The Neo3 will never win any awards for smooth FR, but at least in a dipole its response looks a lot better than anything I've ever seen with their cups on. I'm not going to try to fix the dips at 3 and 7 KHz. They sort of fill up off axis, anyway. I suppose the front of the Neo3 (with its metallic grille) really doesn't help FR. Anyway.

        The active crossover does quite a lot of things. It bumps up bass response on the mid-panel, then crosses over to the woofer using an L-R 12db/Oct filter set at 120 Hz. On the woofers (which are tuned at 30 Hz), it helps with BSC, and crosses over at 120 Hz, 24db/Oct at 120 Hz. I had to drop the panel response by 6 dB, too.

        I simulated the whole thing using LSPCad and a DCX2496 module. Came up with something like this.

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        Again - you'd need the .XML file to configure the MiniDSP. I can send it to you if you'd like. PM me.
        Last edited by fjhuerta; 01-06-2013, 09:11 PM.
        Line Array: IDS-25 Clone, FE-83.
        2-2.5 Way:
        Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
        3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

        Comment


        • #5
          Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

          Listening impressions
          Last edited by fjhuerta; 01-06-2013, 08:11 PM.
          Line Array: IDS-25 Clone, FE-83.
          2-2.5 Way:
          Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
          3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

          Comment


          • #6
            Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

            Awesome!
            Fun that more people get into dipoles.
            "It is only Scrooge McDuck and others with a personality disorder who have money as their goal"

            Comment


            • #7
              Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

              wow, those look really nice. good write-up
              " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

              Quote Originally Posted by hongrn. Oct 2014
              Do you realize that being an American is like winning the biggest jackpot ever??

              http://www.midwestaudioclub.com/spot...owell-simpson/
              http://s413.photobucket.com/albums/pp216/arlis/

              Comment


              • #8
                Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                Some pics of the finished speakers.

                I'll be using Flickr... the PE forum's setup really messes up photos!











                Line Array: IDS-25 Clone, FE-83.
                2-2.5 Way:
                Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                Comment


                • #9
                  Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                  Some semi-boring tech stuff.

                  Bass alignment. Sorry professor, my dog ate my homework. I can't seem to find the bass alignment documents. I want to have this speaker fully documented, so I'll re-do it later.

                  Cone displacement. Again - it's dependant on the bass alignment documents. Suffice to say, speaker extension on the dipole is not an issue - there's more displacement on the vented box module than on the dipole. Surprising, to say the least. That's also the reason why the bass box has a bandpass filter, and not a lowpass one. The box is tuned at 30 Hz, and the bandpass filter's low limit is 30 Hz, 48db/Oct L-R.

                  Off axis response. This is interesting. No, really, it is. From 0 to 60 degrees. No bass module included - this is the dipole panel only, corrected for dipole cancellation (using the MiniDSP).

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                  0 Deg.

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                  15 Deg.

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                  30 Deg.

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                  45 Deg.

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                  Line Array: IDS-25 Clone, FE-83.
                  2-2.5 Way:
                  Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                  3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                  Comment


                  • #10
                    Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                    Poor man's power response.Click image for larger version

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                    Line Array: IDS-25 Clone, FE-83.
                    2-2.5 Way:
                    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                    Comment


                    • #11
                      Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                      Super cool project and stellar execution! I particularly found your impressions on midrange response useful and encouraging. I've got a passive 3-way with open mids project in the works (need to pick it up again come springtime) and I'm sure I'll be referring back to your writeup many times.

                      Comment


                      • #12
                        Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                        Originally posted by fjhuerta View Post
                        Nevertheless, when I sat down in the sweet spot and turned up the volume, bass was indeed... strange, for the lack of a better word. It was there - just not the way I'm used to. I'm now assuming that due to the radiation pattern, I was getting bass without so many nodes. As I said before, the level was correct. It was just lighter and far, far more defined.
                        I think this is a little strange because your woofers are still boxes right? Maybe the combination of small woofers that don't dig very deep and the fact that the upper bass is dipole make the illusion of all dipole bass?

                        I hope you continue to explore dipoles, there's a need for more designs that don't cost a fortune I think. If you're not a real bassjunkie a couple of decent 10" or even 8" in an H-baffle will provide enough bass for normal listening levels. Of course you will need some eq, but you have the minidsp anyway so...
                        "It is only Scrooge McDuck and others with a personality disorder who have money as their goal"

                        Comment


                        • #13
                          Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                          Hello Jonas,

                          The woofers are still boxes, indeed. But most of what I missed was above 120 Hz. It was the "weight" I normally associate with boxes, the chestiness of male vocals, etc. It was there, it's just that it sounded different. I haven't yet figured out if I believe all bass comes from the dipole or from the vented box, though. I guess it depends a lot on the music. If I'm listening to pop / rock with synthesized bass, it does sound as if it all comes from the box. With acoustic music, it's far more difficult to say. I suppose if I went even lower in frequency I'd find it even harder.

                          I'm planning to do an RTA measurement (as John Atkinson does, averaging 9 points on an 18" x 36" rectangle around my head) and see what happens during the transition from monopole bass to dipole bass. From what I measured with an MLS signal, there isn't any cancellation or weirdness between both units. They summed properly from 1.3 meters to 3 meters.

                          And yeah.. the speakers are modular so that I can eventually get a pair of 10"s as a bass module and replace what I'm currently using with it - so I can end up with a fully dipolar speaker . As you well said, I already have the MiniDSP, so it should be extremely simple to do it (although a bit expensive)...
                          Line Array: IDS-25 Clone, FE-83.
                          2-2.5 Way:
                          Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                          3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                          Comment


                          • #14
                            Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                            Male vocals are 100 to 900Hz. I saw from your other thread that you looked at woofer-mid XO points from 200 Hz on downward and see you landed at 120Hz.

                            What was your reasoning for trying to push the crossover lower? Wouldn't raising the frequency, e.g. to 400-600, let the boxed/vented pair handle more of the bass duties (perhaps add back the chestiness of male vocals), and free up the mids up even more?

                            And I agree, a pair of RS150's in a vented box can go pretty low, but that's not the issue.

                            Comment


                            • #15
                              Re: The Reflexos: A simple, elegant OB / VB, passive / active hybrid speaker.

                              Raising the crossover to 4-600hz will ruin much of the dipole magic.
                              "It is only Scrooge McDuck and others with a personality disorder who have money as their goal"

                              Comment

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