Test Sub

Discussion in 'Home Theater Projects' started by RichardHOS, Nov 17, 2003.

  1. RichardHOS

    RichardHOS Second Unit

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    I'd like to build a small, reasonably light and reasonably portable sub that I could use to test various environments for low frequency response and appropriate sub location and acoustic treatment. Ideally, I'd like flat output down to around 10~15Hz at a reasonable level, say 75~80dB. I'm thinking small sealed cube with Linkwitz-Transform and modest plate amp, and possible a purpose built active EQ circuit after near-field measurements if the response isn't flat enough. In other words, I'm looking to put together a portable "reference" sub for room setup and calibration.

    It doesn't seem like a PR design is appropriate, but I'd appreciate any thoughts in case I'm heading down the wrong path.
     
  2. Brian Bunge

    Brian Bunge Producer

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    Richard,

    Are you looking for flat anechoic response to 10-15Hz or flat in room to 10-15Hz?
     
  3. RichardHOS

    RichardHOS Second Unit

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    I've thought about that, and I believe flat anechoic would be preferrable, since it will be used in a variety of rooms and designing for a flat in-room response is trying to hit a moving target. If I know the sub is flat, that would provide useful information as to the room's gain to incorporate into subsequent room treatments and EQ settings.
     
  4. RichardHOS

    RichardHOS Second Unit

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    I don't have access to LspCAD here at work, so I'm just fiddling around with WinISD. Looks like a Stryke AV12 in a small sealed enclosure should be capable of 80+ dB anechoic down to 10Hz, but I need to check the excursion at that frequency.

    In my case, the Linkwitz Transform won't really be boosting the low end... I see it more as capping the response above the target frequency. i.e., if I find that 10 watts produces full excursion at the lowest test frequency, then I'll just set the gain for a 10 watt output with constant voltage test signal input frequencies and try to maintain the same SPL throughout the sub's range.

    Something smaller even than a 1 ft cube would be nice for transporting all over the place. Any ideas for suitable 10" or even smaller drivers with the requisite throw to suit this application?
     
  5. michael-e

    michael-e Agent

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  6. RichardHOS

    RichardHOS Second Unit

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    That level wasn't something chosen for adequate listening levels, but rather for an adequate level for measurment using a calibrated mic. Perhaps I should shoot for a bit more than 80dB, but I do want this to be pretty portable. Something like ~50lbs would be nice.
     

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