First DIY sub- Stryke Thunder 12.3- preliminary numbers. . .

Discussion in 'Archived Threads 2001-2004' started by Wes Nance, Feb 15, 2002.

  1. Wes Nance

    Wes Nance Stunt Coordinator

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    Hi,

    After debating whether to try to put veneer on my new sub up here in Western NY (too cold) or put the sub together and veneer when it gets warmer, I decided to put the veneer off and fire it up.

    My sub is a 3ft^3 design (before bracing, drivers, etc.), using the 12" SAE1204 from Stryke audio, and 2 15" Stryke Passive Radiators, tuned to 1400g each.

    I used 3/4" MDF, and installed MDF "donuts" behind the driver cutouts, so I could flush mount the drivers, and still have plenty to MDF to screw into for mounting.

    At the advice of John from Stryke (thanks!) I didn't do the tee-nuts thing, and used 1 5/8" square drive decking screws (he said to use #8 drywall) and pre-drilled the holes.

    Of course I learned plenty along the way about routers, etc., and didn't have a table saw, and learned how flush-trim bits are God's gift to people like me who don't have perfect joints!

    The most problem I had was installing the PR's, as they have a very soft wood frame where the mounting holes are, and my screws were getting pulled through some parts of this frame, splitting it out a bit. I ended up re-drilling some of the holes for more room, but still bunged the PR's up just a bit. I'm sure I'll find a way to cover my mistake once the veneer is on. . .

    So, how does it sound? I didn't really get to crank it, but I think it sounds pretty good! I don't really have much of a frame of reference, as my last sub is a Polk PSW 250 8" with really no output below 35hz. DVD's really sounded good, and I liked the music, also.

    Using my eye/hand, it would appear that the fb of the sub is around 21hz or so, which is pretty consistent with Unibox prediction.

    Here are the corrected Radio Shack meter readings, running the Styke bass CD through my receiver to the sub with the mains turned off and the crossover on the sub all the way up:

    17.5hz 75db

    20 77

    22 76

    25 76

    28 82

    32 82

    36 81

    40 81.5

    45 83

    50 80.5

    56 67.5

    63 71.5

    71 78.5

    80 68.5

    89 65

    100 72

    I would appreciate any comments/suggestions anyone has. My 300-794 PE plate amp is supposedly disabled boostwise, but the other threads are showing that this really is down 3db at 20hz, which would explain some of my lower readings. If I enabled the 1db bass boost at 20hz on the amp, I think it would flatten the bottom out a bit.

    I'm a bit confused about the readings at 56hz and 80-90hz. Any ideas? My room is around 16 feet deep by 25 feet wide, with an open doorway to the kitchen in the back right rear wall.

    Anyway, there it is, my first attempt! I have a few pics, I'll try to post them soon. I think it sounds good- I don't hear it leaking anywhere. . .

    Thanks,

    Wes
     
  2. Jack Gilvey

    Jack Gilvey Producer

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    Congratulations, Wes, sounds great. [​IMG]
     
  3. Wes Nance

    Wes Nance Stunt Coordinator

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  4. Jack Gilvey

    Jack Gilvey Producer

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  5. Wes Nance

    Wes Nance Stunt Coordinator

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    Jack,

    I just took another look at your sub pics. Your PR's are definitely different around the edges. Mine don't have such a thick gasket- is that rubber on yours? These have a thin wood frame around the surround, and there's not much room for the screws, I should have probably used #6 drywall instead of the #8 equivalents that I used, as the head of the screw is a bit too wide at the bottom of the hole most of the time. . . I probably could have avoided it with slightly wider radius on the pilot holes. . .

    I bottomed out the sub today on Toy Story 2- I was showing off for the kids (my wife Shannon was out. . .) and turned it up a bit, but I think my bass management was all screwed up on the receiver. I'm guessing the the LFE was just way too high for the level of the mains, since I was well below reference level on the mains, but one section definitely bottomed out- I think it was the PR's, as it was a really sharp cracking sound. I backed off the volume immediately quite a few notches, looked at my SPL meter then (didn't bother looking before) and it was still reading around 108db peaks uncorrected. So, I think it was *way* too hot. . .

    I went back and checked my receiver sub setting and it was at +6 db (SVS recommends -6) so I need to balance everything out again with the new sub and try again.

    That bottoming out sound is real scary! Any other protection for that besides the bass boost filter or a BFD?

    Will the sub handle things a bit better after it's broken in?

    Thanks,

    Wes

    ps if I listen to music now without the sub on, it sounds like it's in mono. I'm ruined for life, I think. . .
     
  6. Jack Gilvey

    Jack Gilvey Producer

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  7. Wes Nance

    Wes Nance Stunt Coordinator

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    Just for some perspective on how messed up my bass settings were yesterday:

    Yesterday:

    subwoofer set at +6db on receiver, gain on amp at 12 o'clock

    Today (after calibrating with Avia):

    sub set at -6db, gain on amp at 11 o'clock

    So, wow, I was really hot yesterday. . .

    Also, those are *sweet* looking PR's you got with those big gaskets. Do I remember you bought those directly from Lambda when they were still direct selling?

    What did you use to weigh your PR's? I had a kg baby scale (for weighing babies. . .) but it only had a .01kg resolution. I think the PR's are weighted close enough, though, they have identical amounts of wood, and washers, and the same bolt and nut arrangement.

    I've had a bit of a learning curve with my Denon receiver, in that I didn't realize it resets the channel levels for different input- eg my Dolby Digital LFE is set to 0db, with the master sub out set to -6db. But then I was listening to a CD last night, and the bass seemed really loud from the sub- checked the levels, and on the CD input, the master sub out was back to 0db, so my level was 6db higher than on movies. So I set it back to -6, and it sounds much better. . .

    Wes
     
  8. Jack Gilvey

    Jack Gilvey Producer

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  9. John E Janowitz

    John E Janowitz Second Unit

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    Hi Wes,

    The PR's you got were my closeout ones. Lambda and I both used to use the MDF gaskets like the ones you have. I actually bought all the parts from Nick in the past. Since then I've sourced some parts on my own, including the rubber gaskets like Jack's PR's have. The closeout PR's with MDF gaskets were $25-$35 depending if they were B-stock PR's as well. The new ones with the rubber gaskets are the standard $65 price. The old gaskets did have some problems with cracking, mainly when people removed screws. That was the reason for the change to the rubber gaskets.

    FYI though, the rubber gaskets typically do not provide an adequate seal to the enclosure. I'd still go with some closed cell foam weather stripping on the back. The cheap $1.80 stuff from Home Depot works fine.

    John
     
  10. Patrick Sun

    Patrick Sun Studio Mogul

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    Heh, Toy Story II claims another subwoofer. That burst of rockets around 50 seconds into that movie will just about bottom out any ported sub played loudly (unless it's ported really really low). If nothing else bottoms out your new sub, I wouldn't really worry about it, just take it easy for the couple of minutes when you watch Toy Story II later.
     
  11. Wes Nance

    Wes Nance Stunt Coordinator

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    John,

    Thanks for stopping by!
     
  12. Wes Nance

    Wes Nance Stunt Coordinator

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    Patrick,

    I'll have to try Toy Story 2 again later today, and try to find the max safe level on my receiver so I know for the future.

    I'm not really sure how badly the sub did, as I was running the sub *way* too hot in relation to the mains! Backed off like 6 or 7 notches on volume on my Denon, and still had 108db in other parts of the intro!

    OOPs. . .

    I've been too timid to try it again, and have to wait until Shannon leaves the house for a while- she came home during my sub killing, and from the driveway thought the house was coming down. . .she didn't enjoy it- double oops. . . (although the kids thought it was great!)

    Wes
     
  13. John E Janowitz

    John E Janowitz Second Unit

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    Hi again Wes,

    The SAE1204 is actually almost identical to the Dayton DVC. The VC length and gap plate thickness are the same. The 14.3mm that we list is the VC overhang because I have not sent one to DUMAX. However, if sent to DUMAX, it should measure identical to the Dayton.

    The screws should be fine too, as long as they don't really push the gasket into the surround like you said. A #8 screw shouldn't be capable of pushing it far enough to touch the surround.

    John
     
  14. Jack Gilvey

    Jack Gilvey Producer

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  15. Jon Torres

    Jon Torres Second Unit

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  16. Jack Gilvey

    Jack Gilvey Producer

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    Yeah, I always use Dumax numbers when available.
     
  17. Wes Nance

    Wes Nance Stunt Coordinator

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    Just an update- I finally think I've done a better job calibrating the sub with Avia to the correct level. I calibrated it dead on even with my mains, so I'll probably bump it up a bit sometime down the road, as I'll never really listen at reference level.
    But at 00 on my receiver, which is where reference level should be with my current calibration levels, I get around 115db in room from my listening position when the sphere exploded in the new THX splash before Episode 1 (Star Wars)
    Is that about right? I don't really have any great need to listen to it that loud too many times! My ears were ringing for a bit. . .but the sub didn't sound like it had a problem.
    You guys and your 115db anechoic at 20hz (ultimate driver thread) are out of control! [​IMG]
    Wes (my sub is 15db quiter than a jet engine and it's the gentle sub on this forum) Nance
     
  18. Patrick Sun

    Patrick Sun Studio Mogul

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    Wes, do yourself a favor and use earplugs when you are going balls-out on calibrating to reference.
     
  19. Brian J Dupuis

    Brian J Dupuis Second Unit

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