New Sub - Please take a look at the spl's

Discussion in 'Archived Threads 2001-2004' started by Dom H, Sep 14, 2002.

  1. Dom H

    Dom H Agent

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    MJ Acoustics Pro 50
    Denon 3802
    Room aprox 13'x12'
    Excel Sheet - Click here then open or save
    I am thrilled with the British Pro50, okay it's small (8" 50watt sssh!) but it's very tight and has superb transient response. The thing is the readings are a little confusing, why am I not getting a sharp rolloff ~25Hz?
    Any comments on the readings and any extra thoughts on reducing the hump around 60Hz (I think they are combining with my mains x-overed at 80Hz) altering the phase has reduced it slightly.
    Dom.
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    The folder is empty, I don't see a file with the name "pro50".
     
  3. Sebastian

    Sebastian Second Unit

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    Yep, it is empty, could not find file either.

    OT:
    Chris did you get my PM?
     
  4. Dom H

    Dom H Agent

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    Fixed
     
  5. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I'll check now
     
  6. James Bergeron

    James Bergeron Supporting Actor

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    Not bad, fairly flat, seems a little low though. You could probably EQ that hump. I'm having a hard time to believe that 8" sub goes that low (16hz) your probably hearing harmonics right up to 25hz or so. You have a small room which helps you out.

    You may want to actually run the tests at 0 or -10db, -30 is a little low to give actual readings in my opinion.
     
  7. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    If the room is fairly sealed...no large openings to other areas...rom gain will start in the mid 40s. Adding (in theory)12dB/octave. In the real world...figure 9dB/octave max. But that is still 9dB by 22hz and about 15dB by 16hz.

    If you can measure the subwoofer outside(50-60ft from the nearest reflective boundary) this will give you an easy way to find out what the room is adding to the low freqs.

    TV
     
  8. Dom H

    Dom H Agent

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    I have updated the file for my usual listening level -10dB (if my amp is callibrated to dolby 105dB, what volume will a cd of tones be with the volume at -10dB, 95dB?)
    What is going on, how am I getting a flatish response all the way to 16Hz from an 8' sub with 50 watts?!? The door was rattling like crazy at 16Hz!
    here is the sub MJ Acoustics Pro 50
     
  9. James Bergeron

    James Bergeron Supporting Actor

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    Dom, did you hear the 16Hz? Or did the room just feel like a huge pressure chamber?
     
  10. Dom H

    Dom H Agent

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    No I couldn't hear it only feel it. The door would vibrate at 16 & 18Hz.
     
  11. James Bergeron

    James Bergeron Supporting Actor

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    Well sounds like you have a very good sub, I think your sub is helping out. Seems almost impossible though.
     
  12. Jack Gilvey

    Jack Gilvey Producer

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    I'm somewhat skeptical of the ability of an 8" driver and 50 watts to produce much useable output @ 20Hz and below.
     
  13. Dom H

    Dom H Agent

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    I have repeated the test at least half a dozen times all with similar results. I also have double checked the RS spl meter corretion values.
     
  14. Jack Gilvey

    Jack Gilvey Producer

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    Cool. How have you accounted for THD?
     

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