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Maximum Clean Output from Subs

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  • Maximum Clean Output from Subs

    There is a thread at AVSForum about dual MFW-15's vs a VTF-3.3/MBM-12 combo. Since I upgraded from a VTF-2.3/MBM-12 combo to dual MFW-15's I decided to participate in the thread. I referenced Craig's output measurements from his subwoofer review thread. Pete from Hsu responded with the following:

    Originally posted by Pete_Hsu
    I don't agree with that assessment on the VTF-3 MK3's output capabilities. Dual VTF-3 MK3's in the max output mode will have between 124-128db max "clean" output capability (using CEA 2010 tone bursts and stepped distortion limits) from 25-100Hz, and 118db max clean output capability @ 20Hz (measured @ 1m distance, outside).

    Note that a single VTF-3 MK3 in max output mode has an average of 3db more distortion-limited output from 20-100Hz compared to the VTF-2 MK3. So dual VTF-3 MK3's would give up to 9db (!) higher output capability compared to a single VTF-2 MK3. To put that into perspective, it would take three VTF-2 MK3's to match the clean output capabilty of dual VTF-3 MK3.
    Pete's numbers are at 1m vs 2m for Craig's tests. Ilkka also measured the VTF-3.3 (at 2m) with results posted at the HomeTheaterShack. How is Pete getting such high numbers? Can any changes they might have made to the VTF-3.3 really produce such a high output?

    For disclosure, I own 4 Hsu subs and 3 av123 subs. I hope to compare the VTF-2.3/MBM-12 combo again against the dual MFW-15's (if I ever get the time).

  • #2
    Originally posted by mojave
    How is Pete getting such high numbers? Can any changes they might have made to the VTF-3.3 really produce such a high output?
    You said it yourself. Measured at 1 meter vs 2 meters.

    Also manufacturers usually tend to inflate specs where they can. Not saying this is the case here though. :no clue:
    ------------------------------------

    http://www.chasehometheater.com/foru...php?albumid=14

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    • #3
      It's a good 12" sub with some major output. Tough to compete with the big boys using 15" drivers however.
      Time waits for no man.

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      • #4
        I could be wrong (and probably am) but when I read Pete's comments I figured he was referring to in-room response. Obviously the results would be significantly different than a ground-plane output test.

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        • #5
          Does anyone know the conversion factor for going from 2 meters to 1 meter?

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          • #6
            Originally posted by JimP
            Does anyone know the conversion factor for going from 2 meters to 1 meter?
            I may be wrong (I would search...just off the top of my head) but I think 6 dB decrease vs 1m?
            :scratchchin:

            Mike
            HT Gear (AVS Link)
            Rk: MA WR-37-32
            Pwr: 20A, Surge-X SEQ, M1500-UPS
            Proj: JVC RS20, 128" 2.4:1 CaradaBW, ISCOIIIL, CineSlide, RadianceXE
            Cbl: DirectTV C31/700 Genie receiver
            Rec: 5308CI + XPA-3
            BR: Oppo BDP-103
            Gm: 360 Pro
            LR/C: RS1KSig/RSC200Sig
            S/R: RSS300/RS250MkII
            Sub: SVS PB12-Ultra/2
            Off: HRT MS DAC, USP-1, UPA-2, ERC-1, Ultra10, WAF-1 Ninja+No-Rez
            Off2: Gizmo, WAF-1
            TCA: 3x Gizmo 1.0or,5x v1.0M; 5xWAF-1

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            • #7
              Hi guys - When going from 2 meters to 1 meter, one would add 6 dB to the SPL in a Ground Plane setting, and adding a second subwoofer would also add 6 dB.

              In order for Pete Hsu's claim to be true, a single VTF-3.3 would have to deliver 106 dB at 20 Hz at 2 meters groundplane.

              That's a lot of output from a single 12 in a moderate sized cabinet, and definitely more output than we got here by about 4-5 dB.

              It's still a great subwoofer, though. :huge:

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