My DIY Tempest

Discussion in 'Archived Threads 2001-2004' started by Mark Fitzsimmons, Aug 22, 2002.

  1. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    I finished my Tempest sub last night. It is 122L sealed. Took me like two days to build, but 8 days waiting for the Tempest to get here from Adire; they shipped it on time, but it took UPS that long to get it to Ohio.
    I haven't had that much time to listen to it. I watched the Lord of the Rings last night with it and was blown away. This is the first time I experienced bass I can feel in a Home Theater environment; I like it [​IMG] For movies this thing rocks.
    Then I listened to a little music. The bass is really tight and accurate, not boomy what-so-ever. But I am not just getting the thump I want. I assume the solution is to mod the amp for some bass boost in the 30hz or so range, but I don't want to do this and comprimise movie fidelity. Is there anything else I can do? For music I already maxed out the level knob on the amp, when it was at a little less than half for my movie calibration: speakers at 75db, sub at 79.
    Well here are the pics.
    www.markfitzsimmons.com/sub/
    Notice I flushmounted the sub, its hard for the pics to reflect it but it looks amazing. Definitly worth the extra time. It's really easy to do, because the height of the Tempest is .75" so get a sheet of MDF this thick and you're in business.
    I still need to beautify the sub, which I'll probably get done in the next few days, but for now I was just itching to hear it so it's naked [​IMG]
    A special thanks goes out to Dustin B who answered nearly all my questions for this project. It probably wouldn't have happened without his help.
     
  2. Patrick Sun

    Patrick Sun Moderator
    Moderator

    Joined:
    Jun 30, 1999
    Messages:
    38,717
    Likes Received:
    463
    Can anyone else see Mark's webpage with the sub pix?
     
  3. Brian Bunge

    Brian Bunge Producer

    Joined:
    Sep 11, 2000
    Messages:
    3,716
    Likes Received:
    0
    Pat,

    I saw them!

    Brian
     
  4. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Another note, whats the best way to set the phase?
     
  5. Rick Guynn

    Rick Guynn Second Unit

    Joined:
    Mar 23, 1999
    Messages:
    473
    Likes Received:
    0
    The easiest answer to your question is to get a BFD. You can EQ your sub for HT and store it on one preset, then EQ for music (adding whatever boost in the desired frequency range) and store it on another preset. Heck, there are 10 presets to choose from, so go nuts!

    Just remember that any boost removes headroom from your amp.

    RG
     
  6. Rick Guynn

    Rick Guynn Second Unit

    Joined:
    Mar 23, 1999
    Messages:
    473
    Likes Received:
    0
    An easy way to set the phase is to run a sine wave through your receiver at the crossover frequency, read the SPL with a meter, and adjust the phase until the SPL is maxed.
    Alternately, is you happen to have a O-Scope, you can hook the oscope to a mic and actually watch the signal as you adjust it [​IMG] ( I tried this, it's neat)
    RG
     
  7. jeff lam

    jeff lam Screenwriter

    Joined:
    Jun 4, 2001
    Messages:
    1,798
    Likes Received:
    0
    Location:
    San Jose, CA
    Real Name:
    Jeff Lam
    Rick,
    That's exactly what I do with my BFD. I have two presets, one for movies and one for music. It helps out a lot.
     
  8. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Joined:
    Feb 1, 2002
    Messages:
    1,865
    Likes Received:
    0
    I am beginning to wonder on your placement of the subwoofer because I have the gain set to half way on my 250w amp and the receiver level to 3/4.

    Is it in a corner of the room so as to activate all the bass modes?

    Phase didn't affect my subwoofer all that much, maybe about 3 db when I changed it 180 degrees. The thing about adjusting phase is when you change it at one test tone, it affects another so you may have to find a comprimise in the phase adjustment.

    What I hate about bass is when it begins to sound boomy like my ear is in a high pressure zone. This is where room placement in relationship to the listener and speakers can have an impact.

    The tempest CAN sound boomy if placed wrong, I figured that one out...
     
  9. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    It is in a corner.
    http://www.markfitzsimmons.com/sub/DSCF0041.JPG
    I just recalibrated using the Fight Club THX tones. The level on the sub amp is around one third, and on the reciever side.
    Left main: +6
    Center: +1
    Right main: +5
    Surround right: +0
    Surround left: +0
    Subwoofer: -7
    The crossover is at 160 on the amp, but my reciever is crossed at 80hz on the subwoofer output.
    Will someone make me an 80hz sine wave tone so I can set my phase?
     
  10. Patrick Sun

    Patrick Sun Moderator
    Moderator

    Joined:
    Jun 30, 1999
    Messages:
    38,717
    Likes Received:
    463
    Ah, Mark's using port 8000, and I'm sure our company's firewall doesn't allow traffic through that port anymore.
     
  11. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Yeah, my ISP blocks port 80, but there's always a work around [​IMG]
     
  12. Pete Mazz

    Pete Mazz Supporting Actor

    Joined:
    May 17, 2000
    Messages:
    761
    Likes Received:
    0
    I would try facing it in a different direction. It looks like it fires right into the big stuffed sofa. Try pointing it up or even into the corner and see what you think.

    Pete
     
  13. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Unfortunatly, I can not mount it firing up because the amp is on the panel opposite the sub driver... [​IMG] but I'll try pointing it in other directions.
     
  14. Bryan Michael

    Bryan Michael Supporting Actor

    Joined:
    Mar 2, 2002
    Messages:
    564
    Likes Received:
    0
    after breaking it in it will be alot louder when i first got my sub i turned it up and it barley had any bass and now it is broken in it hits hard
     
  15. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Its not that its not loud enough. Its just that in order to get acceptable levels of bass for music I have to turn it up alot. I leave the level fixed on the amp, but turn the reciever from -7 to +3 for music. At this level, it sounds good to me.
    I wanted to see what levels the sub was capable of pushing. So I unhooked my mains and played just the sub on Pink Floyd's "One of These Days" and measured 118 db at the listening position. [​IMG] It was really loud, much louder than I'd regularly listen at.
     
  16. Patrick Sun

    Patrick Sun Moderator
    Moderator

    Joined:
    Jun 30, 1999
    Messages:
    38,717
    Likes Received:
    463
    Okay, finally got to see the pix. So, now do you know why people go the DIY route when building subwoofers? [​IMG] The performance/price ratio is mighty high once you get a good plan/design in place.
     
  17. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Yeah, cost me under $300 so far, and sounds great!

    I had people over at 8:30 to watch Shrek tonight, everyone was so impressed with my system I spent the rest of the night (its just past 12 now and everyone just left) demoing my system.

    I'm begining to love DIY. I'm going to get a projector soon and will make a DIY screen, and probably a flexy rack that will fit below my screen to hold my components and function as a center channel stand.
     
  18. John Parris

    John Parris Stunt Coordinator

    Joined:
    Aug 10, 2002
    Messages:
    235
    Likes Received:
    0
    Looking good, man [​IMG]
    You've definately given me more hopes about my own Tempest project. [​IMG]
     
  19. Jason Hammerly

    Jason Hammerly Supporting Actor

    Joined:
    Oct 28, 1999
    Messages:
    739
    Likes Received:
    0
    I was going to do the same design. Trying to decide if I want to do a front firing or bottom firing. any opinions?
     
  20. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

    Joined:
    Aug 18, 2001
    Messages:
    539
    Likes Received:
    0
    Jason, when I was planning my sub, I was faced with the same decision. I was told that whether I went front or down firing the sound would be the same either way. I chose to go with front firing because it would make the sub a little lower profile and whats the point in having a big 15" driver if you can't look at it [​IMG]
    Either way, you can't miss.
     

Share This Page