Onkyo Rebuild

Discussion in 'Speakers' started by Morgan_, Jan 26, 2005.

  1. Morgan_

    Morgan_ Stunt Coordinator

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    I know this thread should probably be posted in the DIY, but some other members were interested in the rebuild I did, so I'll post it here.

    The Project

    My goal, to turn a so so Onkyo sub that was part of an HT package into a real performer worthy of second system duties. This was how the sub looked originally:

    [​IMG]

    Sub is a down-firing type, down-firing onto a base below enclosure, and front fires a tuned port. Original port was a 4", about 8" long, and by my estimate, tuned at 47hz or so. Not very deep tuning, but original sub tested to about a solid 40hz before rapidly falling off. Original amp was listed at 150watts "dynamic", and had a electrical rating of 75watts. It was a little thing:

    [​IMG]

    I started the rebuild project by stripping everything from the enclosure. I relocated a cross-brace inside the box so it would not interfere with my new port that I was putting in. The new port is a massively flared 3" x 11.5" aero style port, that is tuned to the volume of the box, 1.4cu-ft, and port tuned freq. will be 31hz. The port requires that I enlarge the hole to a whopping 5.75", as it flares from 3" to over 5".
    Port pic:
    [​IMG]


    So the holes were enlarged, both for the new amp and port.
    Here's a pic of new 240watt amp:


    [​IMG]

    After the holes were all enlarged, I used a dampening spray.
    When I ordered it, I wasn't sure of it's effectiveness, and it was pricey at $17 for the can. I spray all inside surfaces with a good layer, and let it dry. Like I said, I didn't know if it would have any great effect, but surprise, it does do a good job. I knocked on the side and you could tell of it's dampening effect.
    [​IMG]

    I then added a layer of accousta stuff on the front baffle wall.
    Now I was ready to install everything. I drilled small pilot holes for all my screws and it worked well, they all torqued to a number 2 setting on my makita really nice.
    Pics of finished Sub:

    [​IMG]

    [​IMG]

    close up of port:

    [​IMG]

    I ordered a new subwoofer, although original Onkyo subwoofer was surprisingly stiff, tight and strong, and I was surprised by it's performance in new setup. It easily hit a very solid 25hz at good volume.

    Pic of new subwoofer:

    [​IMG]


    I got a chance to really crank this thing today, and it's awesome!! It's tight, quick and LOW! Very musical and blends well with the two satellites I made>> [​IMG] you can't tell where the bass is coming from, and when I really cranked it up, I played some "50 cent", walked to the kitchen, and the bass was still very much present and solid, just shooting through everything and filling the space. This sub has a filling effect I've never heard from an 8". If I played it for someone, they wouldn't ever know it was just an 8, sounds beefier and larger. It has exceeded all my expectations I had for it, and in the end very much worth the $195 I spent. Lot's of fun doing it too!! Peace. -Morgan [​IMG]
     
  2. Eric Hargrove

    Eric Hargrove Stunt Coordinator

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    Looks good, Morgan. It's also a good feeling to know you did it yourself.[​IMG]
     
  3. Xavier_X

    Xavier_X Auditioning

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    Nice work on the sub! I have the same Onkyo sub, and while I don't have the skill to modify it like you, I did want to put a pound of fiber-fill inside of the sub to cut down on the boominess a little. Several other owners of this sub have said it helps a lot.

    However, when I opened up the sub, I didn't know how I could assure that the fiberfill wouldn't touch the amplipher and catch on fire.

    Do you have any suggestions for how I should place the fiber fill? I bough a bag of the poofy stuff, like what would be in a stuffed animal. Should I have gotten the strips (about 1" thick) instead? Should I try gluing it to the inside walls of the sub?

    Any tips would be appreciated!
     
  4. Geoff L

    Geoff L Screenwriter

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    In order to get the max from your filling you need to subtract the volume your amp, driver and port take up in the box to get an ~{accurate internal cubic volume}~.

    Then this chart by TN, the renouned sub testing god, can be of help to you.

    If your driver/woofer is vented threw the back plate, (hole in magnet) make sure it's got a screen in it, (or tape a piece over it).
    The (amp is fine), but trying to keep the fill from touching the transformer if it's exposed, sure won't hurt, especially if you run/push it hard all the time.

    My Acousta Stuff™ (poly fill) lays right against my large transformers in my Sealed subs, no problems after 2 plus years. Others have seen no problems either with fill touching the amp...

    The ~{Most Important Thing}~ is keeping the fill from getting into, or sucked into the port!!!

    Heres a TN testing fill chart that will help explain a few things along with actual measured results. You can see it here at this **helpfull poly filling chart**..

    Regards
    Geoff ¥
     
  5. Xavier_X

    Xavier_X Auditioning

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    That link is dead. [​IMG] Thanks for the tips though, Geoff. Just as long as I know it won't catch on fire, I'm happy. [​IMG]
     
  6. Geoff L

    Geoff L Screenwriter

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    Sorry bub, the daw gone thing worked when I posted it. [​IMG]

    Checked a couple other links that are the same thing, and their dead too!

    In TN's poyfill chart for testing a 1.4cf^³ Ported box, best gains where seen with 1 to 1.5-lbs of poly fill. Showing a 30 to 40% (internal volume increase/gain the "driver now sees"). After 1.5-lbs, any more and the Reverse effect happens.

    Thats allot of fill in a small box, also it's ported. His measurments WERE for a ported box, again 1.4cf^³,,,, also LESS DRIVER, PORT, AND AMP VOLUME to obtain the actual starting internal working volume of 1.4cf^³.....!

    FB-drops/the tuning point, due to the fluffed polyfill...

    You can try that much, 1.5-lbs,,, but I'd be more apt to try a 1-lb as you'll find after fluffing it up, it's (allot to stuff in their) and keep away from the port/vacume cleaner..[​IMG]

    You can test the stuffing results with a simple spl meter and test tone disc to see where your tuning has now dropped also, assuming you leave the port length and size/width alone. When the "driver moves the least at a gven frquency" and then begins to move "more above & below that freq", your very close to it's tuning. It will definetly change the subs FR threw it's working range and not just lower it's tuning point..

    Maybe the link will start back up, or someone can find it else where and post it....

    The darn link did work! [​IMG] [​IMG]

    Cheers
    Geoff ¥
     

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