how loud is your Tempest at 20Hz?

Discussion in 'Archived Threads 2001-2004' started by Manuel Delaflor, Jul 20, 2002.

  1. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Regarding this review:
    http://www.hometheaterhifi.com/volum...s-12-2001.html
    I think it would be interesting to see which are the results of people with Tempest DIY subs.
    My own Tempest is on its way home, and I will do my own tests with a calibrated mic and some RTA software. But in the mean time and returning to the cited review... what "Shake Value" have you found in yours?
     
  2. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Just to not let die this post... (97 readings)
    Do someone with a Tempest has done any kind of SPL tests at 20Hz?
    [​IMG]
     
  3. Pete Mazz

    Pete Mazz Supporting Actor

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    Comparing everyones in-room listening position SPL at 20 Hz is basically pointless. You certainly couldn't compare it to the article, as you'd have to have the same control (room and mic positions, etc.)

    Suppose, for instance, that I had a huge null at 20 Hz in my room. If I came back and reported that I could only achieve 70 dB, you'd think my sub was a poor one. You'd be wrong.

    Pete
     
  4. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Pete,
    Thanks. I'm aware of that. Every room is different, but lets say that several users take readings... I think at some point the numbers will begin to reflect a pattern.
    For example, if SVS 25-31 and 16-46 users did the measures, I think that a pattern reflecting more bass from the 16-46's will be easily seen.
    Granted, the SPL needs also to be taken with the same equipment. But also I would say that most DIY guys should have a RS SPL Meter, so the readings will be more or less equalized.
    Finally, this is just a request, Im will not use the data to publish a scientific article! [​IMG]
     
  5. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    The test will be rather difficult because not everyone has 20hz test tones at the right level.

    If I used my 20hz test tone I downloaded it would be too loud if my theater was set to reference level.

    All I know is that when I did tests in the 20hz range all I achieved was a slow rumbling floor and barely audible noise. The Radio shack meter isn't designed for those deep notes and a lot of adjustments are needed to the readings. I could hardly get a reading from 20hz test tones compared to say 80hz tones at the same volume.

    If I turn it up, the driver moves like mad and there's not much distortion, but a little amount of sound comes from the driver if the rattles of the house don't drown it out. The distortion that is there at 20hz could be described as a warble quality of the bass tone as opposed to smooth consistant "hum" bass. However, I havn't auditioned subs playing tones at 20hz so I wouldn't know.
     
  6. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Chris,
    Thanks for the reply.
    I can see that this topic is of NO IMPORTANCE for the DIY community. I was expecting a LOT more interest.
    Anyway, I will do my own tests with a calibrated mic and most likely will keep the results for myself... [​IMG]
     
  7. Patrick Sun

    Patrick Sun Moderator
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    Nobody listens to a continuous 20Hz tone loudly as an idea of a good time.

    Most DIYer care more about a smooth response curve, and transient response for their subwoofer projects.
     
  8. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Patrick,
    Thanks for your response. I know nobody listen to a 20Hz tone, as the reviewers do, as the manufacturers do. Still, the frequency response appear to be relevant from the point of view of the buyer.
    I have seen countless examples of this regarding subwoofer topics in this and other forums. I have seen also that a good DIY sub will should outperform almost any comercial design.
    Still, no one has offered a comparision between a DIY and a SVS (for example). All I see are theoretical proyections of how well everybody DIY Subwoofer WILL sound based on design programs. All I have found are readings with "correction files" on SPL Meters. Nothing about real instruments reading real numbers.
    I keep thinking that such a comparo would result interesting. But apparently Im alone with this feeling.
     
  9. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    OK, from listening position with my radio shack meter, I achieved 107.5 decibles (adjusted, Slow, C weighted) max from raising the volume as high as it can before distorting. (I don't know what is the exact level for reference when just playing a single subwoofer).
    After listening to the tone for a while it began to make me queasy. Things started to rock back and forth and my pyramid shaped enclosure was shaking.
    If I raised the volume too high I heard distortion as if the driver was bottoming out producing a scratch like warble from the driver. The sub is corner loaded in an 10'x11' room with door open. 15" Tempest powered by PE 250watt plate amp. The box is Adire alignment mod. link
    This result pleases me. 20hz @ 107.5 decibels is good enough for me. I sorta expected it to be around 110.
     
  10. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Chris,
    Thank you a lot! Now that's what I was expecting! Considering you used the SPL Meter, I would guess that your actual result is even better than your measured data. [​IMG]
    Your result put your sub at the level of Twin SVS Ultras with 1,000 watts amplification. WOW.
    Yes, it is only an approximate result, not at all scientific or really suitable for "truth" values. Still, having a "Shake Value" more or less equal to twin SVS Ultra's is quite an achievement.
    I have seen your sub in the past, by the way, while figuring out which will be my proyect when my Tempest arrive. Extremely good work. I wish I can handle wood the way you do. I will go with a Sonotube, much easier for my skills.
    Thanks again. [​IMG]
     
  11. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    NP, actually I have to give credit to the build to my best friend who's a contractor. Without him, attempting a design like that would be very difficult, especially with the lock mitre and factory laminated MDF.

    I owe him so much, it only costed me $80 for wood and he paid for the rest to build it with me. All I did was make the holes in the brace and spend about 3 hours on designs with autocad.

    I recall someone saying that a DIY tempest should compare to twin ultras in output by stats. I also recall the guy from SVS telling me that there's no sense in buying an SVS when you can have a DIY. Those two pieces of advice pushed me to build one.
     
  12. Dustin B

    Dustin B Producer

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    Displacement wise I was under the impression that a single SVS Ultra and a Tempest would be rather close.
    I you are using the Secrets review for your dual Ultra numbers Manuel. Remember those measurements were taken in an over 3000ft^3 room, farther away from the speaker than you can get in Chris's less than 1000ft^3 room (14 or 16 ft if memory serves). Plus without the proper equipment to measure distortion, that number could be at 100% THD.
    None the less, I'm sure a Tempest in a large ported enclosure can outgun every sub on this list at 20hz except for maybe the HE15:
    http://www.avsforum.com/avs-vb/showt...=nousaine+list
     
  13. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Dustin,

    Thanks for the clarifications. I understand now better the numbers and their significance.
     

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