• RE: MY Open Baffle Dipole Sub Results - josh358 12:13:15 11/10/24 (4)
  In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 14, 2024 at 06:28:06

  Tim didn't find a difference between the servo amps and regular amps. Did you try comparative measuring and listening?
  

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  • RE: MY Open Baffle Dipole Sub Results - MarcL 12:28:24 11/10/24 (3)
    In Reply to: RE: MY Open Baffle Dipole Sub Results posted by josh358 on November 10, 2024 at 12:13:15

    I measured a clear difference in the impulse response with and without the servo and between the three damping settings. But I had to use a different amp to test without servo because there is no way to defeat the servo in the Rythmik amp ... there are three settings but you can't run the amp with servo disconnected. And then I had to do the shelf filter with a miniDSP for the other amp because the shelf filters are built into the servo amp too.
    
    Did I try to HEAR a difference? No ... I did not attempt to do that to my brain given that you can't just switch it off and rewiring everything would kill off any sonic memory. But a couple weeks ago I heard a sealed sub built by someone who designs and builds speakers. He made his with two 15" drivers and the Rythnik servo amp and it has the same signature sound that I hear. And that guy said he felt the servo made a big difference.
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    
    

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    • RE: MY Open Baffle Dipole Sub Results - emailtim 18:51:23 11/11/24 (2)
      In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on November 10, 2024 at 12:28:24

      FWIW, when I did my test, I compared the Rythmik servo amp against B&O IcePower 1000ASP amps. "Better" amps may perform better than the amps I tested.

      The 1000ASP amp measured better (REW) with faster dampening/setting than the servo amp using 2 drivers per side (no change in speaker, nor mic positions, just swapping amp feeds). That being said, I did not hear a difference.

      I did not try this test with 3 drivers per side. The 1000ASP amp is stable to lower Ohm loads and has more power than the Rhythmik amp so I would assume 3 or 4 drivers per side would follow suit.

      I used my own FIR dipole compensation filters. The dipole compensation filters in the Rythmik amp can't be defeated without a special control board from Brian D. Same goes for most all of the controls in the plate amp.

      I spoke with Brian D about using the IcePower amps when they first came out. He said he tried to negotiate a deal with the OEM, but they would not add the hooks he needed to make it a servo unit. If they did, the resulting servo would probably benefit from a stronger amp.

      For a while, Brian did have servo amps using a different amplifier, then they were discontinued. I haven't followed the progression since then.

      Brian confirmed he made some one-size-fits-all engineering decisions for the servo amp. He also confirmed that those one-size-fits-all decisions may not be optimal for every application ( by definition ).

      I bought a special board from him to get around this problem and in the end, decided to do all of my configurations in one place instead of playing dueling banjos in case a physical control accidentally got changed. Another dueling banjo was the upstream filters undoing unwanted changes in the plate amp filters (shortest distance between 2 points is a straight line, instead of tacking).

      It also removed another layer of filters and circuitry from the signal chain while allowing more sub amp options. Sold off the plate amps.

      Since the H-Frame cabinet has no backwall/cabinet induced waves, most all of the designs issues the servo was trying to address in a sealed cabinet does NOT exist in an OB/Dipole design.

      If memory serves, the servo amp was designed for sealed and ported boxes, not OB/Dipoles without boxes. The latter application came after the former and required some modifications for that application.

      A370PEQ Dampening Factor:

      The A370PEQ is rated at 370 watts of power into a 4 ohm load.
      Harmonic distortion is less 0.01% at 200WRMS @4ohms (-3 dB from full output).

      Damping factor: 160 @ 4ohms. (Note: damping factor is speaker wires dominated. Without speaker wires, the native damping factor is > 800).

      ICEPower 1000ASP Dampening Factor:

      1000W @ 0.01% THD+N, 100 Hz, 4 ohm

      
      .
      
      2022/03/30 Historical Records CENSORED
      

      • A370PEQ   (Open in New Window)

      
      

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      Edits: 11/11/24   11/11/24   11/11/24   11/11/24   11/11/24   11/11/24   11/11/24

      • RE: MY Open Baffle Dipole Sub Results - MarcL 06:57:57 11/13/24 (1)
        In Reply to: RE: MY Open Baffle Dipole Sub Results posted by emailtim on November 11, 2024 at 18:51:23

        Thanks for sharing this Tim. Good for others to see the perspective you have from trying different methods. After we discussed it last year I decided to do the 3-high and I figured if I start with the Rythmik amp I can get an understanding of how it works and sounds ... always the opportunity to change the method and hardware in the future, but right now I really like the result. I was a little concerned it might not be enough power compared to the rest of my system, but the Dolby Atmos thunder plays cleanly 100db @20Hz so I figure that's good!
        
        A couple weeks ago I visited a guy who built two 2'x2'x2' sealed subs with dual 15" servo drivers each and a Rythmik amp. It must have been an older amp because it had balanced inputs (which have been unavailable for a couple years) and he said it was a 500W Class D. They sounded great!
        
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        

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        • RE: MY Open Baffle Dipole Sub Results - emailtim 09:49:36 11/13/24 (0)
          In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on November 13, 2024 at 06:57:57

          IIRC some of the previous amps were Hypex based.
          
          The balanced option wasn't available when I bought the A370PEQ.
          
          The A370PEQ is a great all-in-one Swiss Army Knife for those that don't have adequate FIR options upstream.
          
          I wouldn't mind 3 or 4 drivers/side either. The extra XMAS and SD help. When I tried 1, 2, 3 and 4 drivers, the performance progression was notable. I can't image those with 6/side.
          .
          
          2022/03/30 Historical Records CENSORED
          
          

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• RE: MY Open Baffle Dipole Sub Results - E-Stat 09:25:41 11/03/24 (11)
  In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 14, 2024 at 06:28:06

  Congrats on extending the dipolar range!
  
  As one who is OCD about some things, however, I find the choice of three drivers odd. You've got more blowing than sucking. ;)
  
  Why not two or four?
  
  
  
  
  
  

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  • RE: MY Open Baffle Dipole Sub Results - MarcL 14:22:05 11/03/24 (10)
    In Reply to: RE: MY Open Baffle Dipole Sub Results posted by E-Stat on November 03, 2024 at 09:25:41

    Well there are a couple reasons for doing three. But ... there is no blowing and sucking. The three drivers are playing in phase. The middle one is physically reversed and the wiring is reversed, so it plays in phase with the other two. All three push and pull together.
    
    Having three drivers results in more surface area so more amplitude for the same excursion. This helps with using the extension filter to play down into the teens.
    
    The reasons for having the center driver reversed ... well that's how the plans were and I didn't feel like altering the plan. But it has been measured that reversing the center driver lowers overall distortion (per Linkwitz and others). It also physically balances the cabinet since the whole thing weighs about 180lbs.
    
    
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    
    

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    • RE: MY Open Baffle Dipole Sub Results - josh358 12:08:01 11/10/24 (2)
      In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on November 03, 2024 at 14:22:05

      Not only does it lower distortion, it partially balances the forces on the baffles. Of course, two or four would be ideal in that regard, but I gather from what people have said that three is the sweet point (and Tim pointed out that four is impossible). This would be not just because of the increased driver area, but because the baffle is larger. (Wonder if anyone has tried putting them side-by-side on the floor for more floor reinforcement.)
      

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      • RE: MY Open Baffle Dipole Sub Results - emailtim 19:35:59 11/11/24 (0)
        In Reply to: RE: MY Open Baffle Dipole Sub Results posted by josh358 on November 10, 2024 at 12:08:01

        4 and 6 per side are possible with a different amp or 2 servo amps per side.
        
        I think there "was" a Hypex-based servo amp that could do 4.
        
        
        .
        
        2022/03/30 Historical Records CENSORED
        
        

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      • RE: MY Open Baffle Dipole Sub Results - MarcL 12:19:59 11/10/24 (0)
        In Reply to: RE: MY Open Baffle Dipole Sub Results posted by josh358 on November 10, 2024 at 12:08:01

        
        
        

        
        I actually did a ground plane measurement out in my back yard with the mic 6ft away. Laying the sub down on the ground resulted in about 2db gain, vs standing up at the same distance. This is with 14Hz extension filter, high damping and 10Hz rumble filter.
        
        I didn't repeat the test with two of them in my room, because I found I can definitely locate the source down to 30Hz and decided to keep them standing next to the 3.7 playing stereo for the 3.7 left/right speakers and of course bass management and LFE is mono to both subs. I also found that mixing a little of each sub to the other (I'm running them through a little mixer to combine LFE) reduced the time component of room resonance at 40Hz.
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        

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    • ??? - E-Stat 15:19:00 11/03/24 (6)
      In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on November 03, 2024 at 14:22:05

      But ... there is no blowing and sucking. The three drivers are playing in phase.
      
      Two one way, the other different.
      

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      • RE: ??? - MarcL 16:14:18 11/03/24 (5)
        In Reply to: RE: ??? posted by E-Stat on November 03, 2024 at 15:19:00

        
        
        

        
        The middle speaker is wired with polarity reversed, so they all play in phase.
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        

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        • Just - E-Stat 16:17:32 11/03/24 (4)
          In Reply to: RE: ??? posted by MarcL on November 03, 2024 at 16:14:18

          The middle speaker is wired with polarity reversed, so they all play in phase.
          
          twice as much frontal radiation than rear.
          
          
          

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          • RE: Just - MarcL 06:52:20 11/04/24 (3)
            In Reply to: RE: Just posted by E-Stat on November 03, 2024 at 16:17:32

            Speakers all radiate from both sides. With an open baffle dipole design the front and rear waves radiate into the room equally but with opposite polarity. The speakers are wired so they play in phase, even though the center one is physically reversed. All three speakers push a positive wave forward and a negative wave to the rear. It's like a figure 8 radiating pattern due to the dipole cancelation at the sides, top and bottom which reduces the response in those directions by around 25db.

            Quote from a forum post "Linkwitz and others proposed that due to the non-symmetrical construction of the woofer, cone, surround etc. they radiate distortion (non-linear properties) at different amplitudes front and rear. If both drivers are in the same orientation these sounds are reinforced. When one of the drivers is reversed, these artifacts are effectively cancelled."

            
            Agilist, Musician, Photographer, Audiophile
            Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
            
            

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            Edits: 11/04/24

            • Exactly! - E-Stat 07:18:49 11/04/24 (2)
              In Reply to: RE: Just posted by MarcL on November 04, 2024 at 06:52:20

              If both drivers are in the same orientation these sounds are reinforced. When one of the drivers is reversed, these artifacts are effectively cancelled."
              
              Siggy's speakers with dipolar woofers (LXstudio, Orion, LX521) use a pair of identical drivers.
              

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              • RE: Exactly! - Beardy 21:24:20 11/04/24 (1)
                In Reply to: RE: Exactly! posted by E-Stat on November 04, 2024 at 07:18:49

                
                With two drivers you turn one forwards and the other backwards and the one facing backwards is wired out of phase (-+ instead of +-). So both drivers move in the same direction at the same time (in phase). The reason is because if the driver motion is non symmetric (it moves differently forwards than backwards), then having one driver face forwards and the other backwards cancels out this source of distortion.
                
                Three is an odd choice. Driven by the needs of more surface area versus the inconvenience of four?
                
                

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                • RE: Exactly! - emailtim 23:01:58 11/04/24 (0)
                  In Reply to: RE: Exactly! posted by Beardy on November 04, 2024 at 21:24:20

                  The choice of 3 - 14 Ohm drivers is because of the combined load (4.6 Ohms) on the servo plate amp.

                  The servo plate amp could not drive 4 - 14 Ohm drivers. Aggregate impedance (3.5 Ohms) would be too low.

                  SW-12-16 parameters:

                  FS 28.3Hz
                  BL 14.07
                  Mms 108g
                  VAS 100L
                  Qms 2.8
                  Qts 0.85
                  Sd 490cm^2
                  Re 14 Ohm
                  X-Max 16 mm

                  Ideally, you would want even numbers of drivers to cancel out non-lineararities of the forwards and backwards cone movements.
                  .
                  
                  2022/03/30 Historical Records CENSORED
                  

                  • https://gr-research.com/product/sw-12-16fr-servo-sub-woofer/   (Open in New Window)

                  
                  

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                  Edits: 11/04/24
• RE: MY Open Baffle Dipole Sub Results - emailtim 14:46:40 10/28/24 (4)
  In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 14, 2024 at 05:28:06

  Hey Marc,
  
  Good to hear you took the plunge.
  
  Did you replace any of your other subs or are you using these in addition to your other subs ?
  .
  
  2022/03/30 Historical Records CENSORED
  
  

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  • RE: MY Open Baffle Dipole Sub Results - MarcL 14:56:16 10/28/24 (3)
    In Reply to: RE: MY Open Baffle Dipole Sub Results posted by emailtim on October 28, 2024 at 14:46:40

    
    
    

    
    Yeah it took a while but I got them built and I spent a lot of time testing. I removed the two Outlaw subs. So these two are all that's running and I have set them up so they cross to the Magnepan 3.7/DWM left and right at 60 Hz through the XKItz active crossover ... one sub each for left and right. Bass management and LFE go to both subs through a mixer.
    
    They sounded great at first, then after a couple weeks of breakin they sound even better.
    
    
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    
    

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    • RE: MY Open Baffle Dipole Sub Results - emailtim 15:06:34 10/28/24 (2)
      In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 28, 2024 at 14:56:16

      Did you try them flat on the floor or against the side walls to extend the long baffle ?
      
      With 6 drivers, you probably don't need the extra boundary gain.
      .
      
      2022/03/30 Historical Records CENSORED
      
      

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      • RE: MY Open Baffle Dipole Sub Results - MarcL 15:52:25 10/28/24 (1)
        In Reply to: RE: MY Open Baffle Dipole Sub Results posted by emailtim on October 28, 2024 at 15:06:34

        I did a ground plane test outside with it standing straight up and it was dead flat way below 20. So I laid it down and got about 2-3db gain. But since in the room I can actually hear the location left/right down to 30-40Hz I decided I really didn't need the extra gain. I have them 3ft from the side wall and 7 1/2ft from the front wall. But I have this extra wood baffle screwed to each 3.7 in the Rooze setup so the sub is against that baffle which gives it an extra foot of baffle length.
        
        With Dirac room correction they go down to 15Hz and play plenty loud for my room. I have the amp set at 14Hz extension, Hi damping and with the 10Hz rumble turned on.
        
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        

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        • RE: MY Open Baffle Dipole Sub Results - josh358 13:46:13 11/13/24 (0)
          In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 28, 2024 at 16:52:25

          Pretty amazing that you can localize them that low in a listening room.
          

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• RE: MY Open Baffle Dipole Sub Results - Beardy 10:47:39 10/15/24 (3)
  In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 14, 2024 at 05:28:06

  Thanks for posting. I have the duals and find them particularly useful in getting a (what I would consider to be), lifelike presence for double bass (trio jazz). When you set these up did you do it all by ear, or have a microphone and some spectral analysis?
  

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  • RE: MY Open Baffle Dipole Sub Results - MarcL 02:49:13 10/16/24 (0)
    In Reply to: RE: MY Open Baffle Dipole Sub Results posted by Beardy on October 15, 2024 at 10:47:39

    You might try a recording by Sasha Witteveen called "...Into the Light". Much of the recording is two double basses playing left and right. Dynamics and depth are excellent and you really can hear the system playing deep bass in stereo. I especially like th etrack "Blew Cheese"
    
    https://trptk.com/shop/spatial-audio-downloads/into-the-light-spatial/
    
    For Jazz trio I like Bill Charlap's "'S Wonderful" and Ray Brown "Live at the Loa - Summer Wind"
    
    
    
    
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    
    

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  • RE: MY Open Baffle Dipole Sub Results - MarcL 15:50:34 10/15/24 (1)
    In Reply to: RE: MY Open Baffle Dipole Sub Results posted by Beardy on October 15, 2024 at 10:47:39

    I use a miniDSP UMIK-1 microphone and Room EQ Wizard software. For the outdoor measurements I used a laptop to run REW and a miniDSP HD as the audio interface to do measurements and to experiment with shelf filters to understand what the Rythmik amp was doing. I measured frequency response, impulse response, etc. This allowed me to see the effects of the different damping and bass extension settings.
    
    And then I listened a LOT and went back and forth listening and measuring to corelate it all.
    
    
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    
    

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    • RE: MY Open Baffle Dipole Sub Results - josh358 13:49:40 11/13/24 (0)
      In Reply to: RE: MY Open Baffle Dipole Sub Results posted by MarcL on October 15, 2024 at 16:50:34

      You make me guilty -- I've been meaning to take my speakers out into the back yard and measure them forever. Not the woofers -- you're equalizing for the room below the Schroeder Frequency -- but above, since you want to prioritize on-axis over power response. (In theory, I can look at a gated measurement, but you know how hard it is to get the gating right with line sources . . . )
      

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