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E-Stat

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.

Follow Ups:

RE: ??? - MarcL 16:14:18 11/03/24 (5)
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
- Just - E-Stat 16:17:32 11/03/24 (4)
  The middle speaker is wired with polarity reversed, so they all play in phase.
  
  twice as much frontal radiation than rear.
  - RE: Just - MarcL 06:52:20 11/04/24 (3)
    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
    
    Edits: 11/04/24
    - Exactly! - E-Stat 07:18:49 11/04/24 (2)
      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.
      - 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?
        
        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)
        
        Edits: 11/04/24

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