Atlas 15 sub

Discussion in 'Home Theater Projects' started by Randy Noel, Jan 18, 2005.

  1. Randy Noel

    Randy Noel Stunt Coordinator

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    Well, it only took a couple years, but my AA ported sub is finally done! I had the box built and ready to drop in a Tempest, but when the time came to order, the Tempests were on backorder. I then read about the Atlas 15 from Ascendant Audio, and went with it. The Atlas dropped into the hole I had cut for the Tempest with no problem. Used port kits and the Rythmik 350 amp from Kyle @ Acoustic Visions. I haven't done any tests yet, but so far I am thrilled with this sub! Watched a Harry Potter movie with my son the other night, and have viewed a few scenes from Monsters Inc. The sub seems to blend beautifully with the rest of my system, (Pioneer VSX 1014, JBL S36 for mains and surrounds, S-Center) and the bass is awesome! Very non-localized and room-rattling. Will eventually try to post some readings and pics. Thanks to Chad and Kyle for all your help.
     
  2. wad

    wad Auditioning

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    I am also looking to build a Adire Alignment Tempest. I also purchased the Rythmik 350 from Kyle. In addition, I bought two 3" flared ports from Adire Audio. Finally, I have two sheets of Birch.

    My only problem, like yours, is that the Tempest is on back order everywhere. I actually paid for one from an online shop, but then got an email saying they were all out. So, now, I'm not sure what to do.

    Can I use the Adire flared ports in another enclosure? Should I just stick to the AA plans, but drop an Atlas 15 in, or would it be a better idea to do a whole redesign (keeping in mind that I would like to use the Adire Audio Flared Ports)?
     
  3. Randy Noel

    Randy Noel Stunt Coordinator

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    My Atlas 15 seems to work great in the Adire Alignment enclosure. From what I could glean before I made the switch to the Atlas, you should have no problems using your existing plans and simply substituting the Atlas for the Tempest, including using the port kits from Adire.
     
  4. Chad Kuypers

    Chad Kuypers Stunt Coordinator

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    Hey Randy,

    I am truly glad to hear that everything is performing to your satisfaction. [​IMG] I look forward to seeing some measurements etc. of how your subwoofer performs in your room. I am also glad to hear that the subwoofer blends well with everything in your system. Fantastic!!





    I thought that it is worth mentioning that at least a dozen people have dropped Atlas 15's into dedicated Tempest enclosures with great success. I have only had positive replies from those who have done it and there would be no problem in doing so at all. Either way it wil perform very well.


    Chad Kuypers
    Ascendant Audio
     
  5. Paul Spencer

    Paul Spencer Stunt Coordinator

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    Randy, I would model it to see how it looks. I would also check the vent velocity. How many flared vents do you have? I would expect a 15" driver such as that would prefer 2 x 4" flared vents of 1 x 6" flared, but a lot depends on the design as you can reduce vent turbulence by:

    * using a rumble filter
    * tuning lower
    * increasing vent diamater
    * increasing flare radius

    You can't say what will be suitable until you use a model which considers these factors.
     
  6. Austin R

    Austin R Auditioning

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    I noticed that Atlas is using the XBL2+(or something) technology. How much of the speaker is the same as the tempest? Are there any specs to compare the two?(Are they the same speaker that is simply re-branded/OEM'd)?

    -Austin
     
  7. Dustin B

    Dustin B Producer

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    Two completely different drivers from two different manufactures. Ascendant Audio just liscensed the XBL^2 motor technology from Adire Audio to use in their drivers. The Tempest doesn't use the XBL^2 motor technology. The closest Adire has to the Atlas 15 is the Koda 15. Which won't have the funky voice coil wiring options, will cost greater than $100 more, is geared more towards mobile use and isn't available yet.
     
  8. Randy Noel

    Randy Noel Stunt Coordinator

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    Paul,

    My sub is built according to Adire's plans for the Tempest based Adire Alignment vented enclosure, which does call for two FP3 port kits. I've detected no port noise at all, and it goes very low. I'll be doing some measurements soon, and will post them when I do.
     
  9. Paul Spencer

    Paul Spencer Stunt Coordinator

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    Randy, keep in mind that you should ideally allow for worst case scenario. I currently have one of my subs with a 4" vent with no flare and I have never heard turbulence in use. However, when I run test tones I find when the driver really starts to move there is a LOT of turbulent noise. There is still vent noise with a 72mm radius flare in fact. This becomes evident in particular when the test tone is around the frequency at which vent velocity has a peak. The worst case scenario occurs at this point where there is low bass without enough signal at other frequencies to mask. As a rule of thumb aim for less than 34m/s when the driver is working at its limit.

    In a nutshell, there may be situations where you can get annoying turbulence, or a "whoooof" at a time when you don't want to hear it. It certainly doesn't hurt to check.
     
  10. Randy Noel

    Randy Noel Stunt Coordinator

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    Paul,

    Are you familiar with Adire's plans? This sub is built exactly according to those plans, the only difference being the use of the Atlas instead of the Tempest. To what "worst case scenario" are you referring?
     
  11. Paul Spencer

    Paul Spencer Stunt Coordinator

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    Randy, I downloaded the Adire plans probably 2 yrs ago, but you really want to model them with your drivers applying max amp power that you have. "Worst case scenario" refers to the point where the vent velocity peaks. There is a point where this occurs and the velocity falls off rapidly above and below this point. Often music content is well above this point, so you can be mislead to think that you will never have a problem. It would take you 5 mins to model this in WinISD pro beta [​IMG]
     
  12. Randy Noel

    Randy Noel Stunt Coordinator

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    If you think it would only take me 5 minutes to model, you greatly overestimate my abilities![​IMG] Seriously, I'm quite a novice. I downloaded WinISD Pro Alpha, and had trouble figuring it out. Kept getting an error when trying to save the parameters from my driver.
     
  13. Paul Spencer

    Paul Spencer Stunt Coordinator

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    Randy, the hardest part with WinISD pro is entering the parameters as it won't allow parameters it thinks are wrong! This means it almost never accepts all of them being entered. What you do is enter the most critical ones, and let it calculate some of them automatically, just check they are approximately right. eg. enter in fs, QTS, VAS and it will come up with Qms etc. You have to experiment a little with this. Try this again and if you really get stuck I can have a go and send you the data file for your driver. I will probably have a go at modelling those AA drivers anyway. To me they look like the best performing drivers in their price range at the moment. The sub driver market has just got quite a bit more competitive!

    Once you get the data in, it's very quick and easy. Enter in box size and tuning. Put in a lowpass filter to match what you have in mind, and a rumble filter if you have one. Go to max power and find the value at the lowest freq you want ie ~20 Hz then use that as the input power. Then check cone excursion that it doesn't exceed xmax. Then have a look at SPL and you see what you actually get. Then look at vent velocity. It should not exceed 34m/s at any point. It would be nice in fact to have this at 17m/s but this is not always possible. I have modelled some adire boxes in this way before and most of them have quite low vent velocity with their intended drivers.

    What you can do with this is find the point at which vent velocity peaks. Then for a "worst case scenario" test, play a tone at that frequency only and turn it up as loud as the driver/amp allows. Or you can try a sweep that runs through that region with a little on either side - eg 15 - 25 Hz. Go to your listening position and see what you think about the sound. If you can't hear any turbulence at all, then you can be sure you will never at any point has a problem with that sub. If it's barely audible, it probably won't be a problem as the sound will 99.9% of the time be masked by other sounds. If it's easily audible then you might think about doing some tweaking. At this point you could:

    * lower tuning a little
    * add a rumble filter if you don't have one
    * increase vent area

    I doubt you would have to do this however. You will probably be fine with what you have already.
     
  14. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Modelling is a good idea before you actually build a sub - to prevent you from realizing you've got a glaring issue after you've spent hours and dollars building the enclosure.

    But we're talking about a completed enclosure here. Sure you could model it with a minimal amount of effort, but in the end it doesn't matter what a simulation says - only the actual performance of the sub matters. Even if the sim showed a high vent speed I wouldn't spend any time trying to fix it unless I actually noticed a problem with the real thing.


    If you've thrown some
     
  15. Randy Noel

    Randy Noel Stunt Coordinator

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    "If you've thrown some
     

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